Forest fire
You are encouraged to solve this task according to the task description, using any language you may know.
| This page uses content from Wikipedia. The original article was at Forest-fire model. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance) |
- Task
Implement the Drossel and Schwabl definition of the forest-fire model.
It is basically a 2D cellular automaton where each cell can be in three distinct states (empty, tree and burning) and evolves according to the following rules (as given by Wikipedia)
- A burning cell turns into an empty cell
- A tree will burn if at least one neighbor is burning
- A tree ignites with probability f even if no neighbor is burning
- An empty space fills with a tree with probability p
Neighborhood is the Moore neighborhood; boundary conditions are so that on the boundary the cells are always empty ("fixed" boundary condition).
At the beginning, populate the lattice with empty and tree cells according to a specific probability (e.g. a cell has the probability 0.5 to be a tree). Then, let the system evolve.
Task's requirements do not include graphical display or the ability to change parameters (probabilities p and f ) through a graphical or command line interface.
- Related tasks
- See Conway's Game of Life
- See Wireworld.
6502 Assembly
ORG $4357
; SYS 17239 or CALL 17239
EMPTY2 = $00
TREE2 = $44
FIRE2 = $99
; common available zero page
GBASL = $26
GBASH = $27
SEED2 = $28
SEED0 = $29
SEED1 = $2A
H2 = $2B
V2 = $2C
PLOTC = $2D
COLOR = $2E
PAGE = $2F
TOPL = $30
TOPH = $31
MIDL = $32
MIDH = $33
BTML = $34
BTMH = $35
PLOTL = $36
PLOTH = $37
lastzp = $38
tablelo = $5000
tablehi = tablelo+25
JSR START
STA V2
LDA #$4C ; JMP instruction
STA SEED2 ; temporary JMP
LDX #$00 ; y coord
table:
TXA
JSR SEED2 ; temporary JMP GBASCALC
LDA GBASL
STA tablelo,X
LDA GBASH
STA tablehi,X
LDY #$00
TYA
clrline:
STA (GBASL),Y
INY
CPY #40
BNE clrline
INX
CPX V2
BNE table
JSR sseed0
JSR sseed2
LDX #$60
STX PAGE
STX TOPH
LDY #$00
STY TOPL
TYA
zero: STA (TOPL),Y
INY
BNE zero
INX
STX TOPH
CPX #$80
BNE zero
loop3:
LDX #0
STX TOPL
LDA #41
STA MIDL
STA PLOTL
LDA #83
STA BTML
LDA PAGE
STA TOPH
STA MIDH
STA BTMH
EOR #$10
STA PLOTH
STA PAGE
loop2:
TXA
STX V2
LSR ; F800 PLOT-like...
; PHP ; F801
TAY ; save A in Y without touching C
LDA #$0F
BCC over2
ADC #$E0
over2: STA PLOTC ; PLOT...
LDA tablelo,Y ; lookup instead of GBASCALC
STA GBASL
LDA tablehi,Y
STA GBASH
; PLP ; continue PLOT
LDY #$01 ; x coord
loop1:
STY H2
LDA (MIDL),Y
STA (PLOTL),Y
BEQ empty
BPL tree
LDA #EMPTY2
doplot: LDY H2
STA (PLOTL),Y
DEY
EOR (GBASL),Y
AND PLOTC
EOR (GBASL),Y
STA (GBASL),Y
noplot:
LDY H2
INY
CPY #41
BNE loop1
LDA MIDL
STA TOPL
LDA MIDH
STA TOPH
LDA BTML
STA MIDL
STA PLOTL
CLC
ADC #42
STA BTML
LDA BTMH
EOR #$10
STA PLOTH
EOR #$10
STA MIDH
ADC #$00
STA BTMH
LDX V2
INX
CPX #48
BNE loop2
JSR QUIT
JMP loop3
empty:
DEC SEED2
BNE noplot
JSR sseed2 ; probability f
LDA #TREE2
BNE doplot
ignite:
LDA #FIRE2
BNE doplot
tree:
DEC SEED0
BNE check
DEC SEED1
BNE check
JSR sseed0 ; probability p
BNE ignite
check:
LDA (TOPL),Y ; n
ORA (BTML),Y ; s
DEY
ORA (TOPL),Y ; nw
ORA (MIDL),Y ; w
ORA (BTML),Y ; sw
INY
INY
ORA (TOPL),Y ; ne
ORA (MIDL),Y ; e
ORA (BTML),Y ; se
BMI ignite
BPL noplot
sseed0:
LDA #$17 ; 1 in 10007 (prime)
STA SEED0
LDA #$27
STA SEED1
RTS
sseed2:
LDA #$65 ; 1 in 101 (prime)
STA SEED2
RTS
default:
LDA #<GBASCALC ; setup GBASCALC
STA SEED0
LDA #>GBASCALC
STA SEED1
LDA #25 ; screen rows
RTS
GBASCALC:
LDY #$00
STY GBASH
ASL
ASL
ASL
STA GBASL
ASL
ROL GBASH
ASL
ROL GBASH
ADC GBASL
STA GBASL
LDA GBASH
ADC #$04
STA GBASH
RTS
QUIT:
LDA $E000
; APPLE II
CMP #$4C
BNE c64quit
BIT $C000 ; apple ii keypress?
BPL CONTINUE ; no keypressed then continue
BIT $C010 ; clear keyboard strobe
BIT $C051 ; text mode
; end APPLE II specific
ABORT:
PLA
PLA
LDX #GBASL
restorzp:
LDA $5100,X
STA $00,X
INX
CPX #lastzp
BNE restorzp
CONTINUE:
RTS
START:
LDX #GBASL
savezp:
LDA $00,X
STA $5100,X
INX
CPX #lastzp
BNE savezp
; machine ???
LDA $E000 ; terribly unreliable, oh well
; APPLE II
CMP #$4C ; apple ii?
BNE c64start ; nope, try another
BIT $C056 ; low resolution
BIT $C052 ; full screen
BIT $C054 ; page one
BIT $C050 ; graphics
; GBASCALC = $F847
LDA #$47
STA SEED0
LDA #$F8
STA SEED1
LDA #24 ; screen rows
RTS
; end APPLE II specific
; COMMODORE 64 specific
c64quit:
; COMMODORE 64
CMP #$85 ; commodore 64?
BNE CONTINUE ; nope, default to no keypress
LDA $C6 ; commodore keyboard buffer length
BEQ CONTINUE ; no keypressed then continue
LDA #$00
STA $C6
LDA $D016 ; Screen control register #2
AND #$EF ; Bit #4: 0 = Multicolor mode off.
STA $D016
LDA #21 ; default character set
STA $D018
BNE ABORT
c64start:
CMP #$85 ; commodore 64?
BEQ c64yes ; yes
JMP default ; no, default to boringness
c64yes:
LDA #$00 ; black
STA $D020 ; border
LDA #$00 ; black
STA $D021 ; background
LDA #$05 ; dark green
STA $D022 ; Extra background color #1
LDA #$08 ; orange
STA $D023 ; Extra background color #2
LDA $D016 ; Screen control register #2
ORA #$10 ; Bit #4: 1 = Multicolor mode on.
STA $D016
LDA #$30 ; 0011 0000 $3000 charset page
STA PLOTH
LSR
LSR
STA PLOTC ; 0000 1100 #$0C
; 53272 $D018
; POKE 53272,(PEEK(53272)AND240)+12: REM SET CHAR POINTER TO MEM. 12288
; Bits #1-#3: In text mode, pointer to character memory
; (bits #11-#13), relative to VIC bank, memory address $DD00
; %110, 6: $3000-$37FF, 12288-14335.
LDA $D018
AND #$F0
ORA PLOTC
STA $D018
; setup nine characters
; 00- 00 00
LDA #$00 ; chr(0) * 8
STA PLOTL
; --- LDA #$00 ; already zero
TAX ; LDX #$00
JSR charset
; 04- 00 55
LDA #32 ; chr(4) * 8
STA PLOTL
LDA #$55
; LDX #$00 ; already zero
JSR charset
; 09- 00 AA
LDA #72 ; chr(9) * 8
STA PLOTL
LDA #$AA
; LDX #$00 ; already zero
JSR charset
; 40- 55 00
LDA PLOTH ; 512 = chr(64) * 8
CLC
ADC #$02
STA PLOTH
LDX #$00
STX PLOTL
LDA #$00
LDX #$55
JSR charset
; 44- 55 55
LDA #32 ; chr(68) * 8
STA PLOTL
TXA ; LDA #$55
; LDX #$55 ; already 55
JSR charset
; 49- 55 AA
LDA #72 ; chr(73) * 8
STA PLOTL
LDA #$AA
; LDX #$55 ; already 55
JSR charset
; 90- AA 00
LDA PLOTH ; chr(144) * 8
CLC
ADC #$02
STA PLOTH
LDA #128
STA PLOTL
LDA #$00
LDX #$AA
JSR charset
; 94- AA 55
LDA #160 ; chr(148) * 8
STA PLOTL
LDA #$55
; LDX #$AA ; already AA
JSR charset
; 99- AA AA
LDA #200 ; chr(153) * 8
STA PLOTL
TXA ; LDA #$AA
; LDX #$AA ; already AA
JSR charset
JMP default
charset:
LDY #$00
chartop:
STA (PLOTL),Y
INY
CPY #$04
BNE chartop
TXA
charbtm:
STA (PLOTL),Y
INY
CPY #$08
BNE charbtm
RTS
; end COMMODORE 64 specific
8086 Assembly
This program expects to run on an IBM PC with a CGA-compatible video card. It uses a field size of 320x200 (the CGA screen) and runs at about one frame per second on a 20mhz 286.
;;; Simulation settings (probabilities are P/65536)
probF: equ 7 ; P(spontaneous combustion) ~= 0.0001
probP: equ 655 ; P(spontaneous growth) ~= 0.01
HSIZE: equ 320 ; Field width (320x200 fills CGA screen)
VSIZE: equ 200 ; Field height
FSIZE: equ HSIZE*VSIZE ; Field size
FPARA: equ FSIZE/16+1 ; Field size in paragraphs
;;; Field values
EMPTY: equ 0 ; Empty cell (also CGA black)
TREE: equ 1 ; Tree cell (also CGA green)
FIRE: equ 2 ; Burning cell (also CGA red)
;;; MS-DOS system calls and values
TOPSEG: equ 2 ; First unavailable segment
puts: equ 9 ; Print a string
time: equ 2Ch ; Get system time
exit: equ 4Ch ; Exit to DOS
;;; BIOS calls and values
palet: equ 0Bh ; Set CGA color pallette
vmode: equ 0Fh ; Get current video mode
keyb: equ 1 ; Get keyboard status
CGALO: equ 4 ; Low-res (4-color) CGA graphics mode
MDA: equ 7 ; MDA monochrome text mode
CGASEG: equ 0B800h ; CGA memory segment
cpu 8086
org 100h
section .text
;;; Program set-up (check memory size and set video mode)
mov sp,stack.top ; Move stack inwards
mov bp,sp ; Set BP to first available paragraph
mov cl,4
shr bp,cl
inc bp
mov dx,cs
add bp,dx
mov bx,[TOPSEG] ; Get first unavailable segment
sub bx,bp ; Get amount of available memory
cmp bx,FPARA*2 ; Enough to fit two fields?
ja mem_ok
mov dx,errmem ; If not, print error message
err: mov ah,puts
int 21h
mov ah,exit ; And stop
int 21h
mem_ok: mov ah,vmode ; Get current video mode
int 10h
push ax ; Keep on stack for later retrieval
cmp al,MDA ; MDA card does not support CGA graphics,
mov dx,errcga ; so print an error and quit.
je err
mov ax,CGALO ; Otherwise, switch to 320x200 CGA mode
int 10h
mov ah,palet ; And set the black/green/red/brown palette
mov bx,0100h
int 10h
mov ah,time ; Get the system time
int 21h
mov [rnddat],cx ; Use it as the RNG seed
mov [rnddat+2],dx
;;; Initialize the field (place trees randomly)
mov es,bp ; ES = field segment
xor di,di ; Start at first field
mov cx,FSIZE ; CX = how many cells to initialize
mov ah,TREE
ptrees: call random ; Get random byte
and al,ah ; Place a tree 50% of the time
stosb
loop ptrees
mov ds,bp ; DS = field segment
;;; Write field to CGA display
disp: xor si,si ; Start at beginning
mov dx,CGASEG ; ES = CGA memory segment
.scrn: mov es,dx
xor di,di ; Start of segment
.line: mov cx,HSIZE/8 ; 8 pixels per word
.word: xor bx,bx ; BX will hold CGA word
xor ah,ah ; Set high byte to zero
%rep 7 ; Unroll this loop for speed
lodsb ; Get cell
or bx,ax ; Put it in low 2 bits of BX
shl bx,1 ; Shift BX to make room for next field
shl bx,1
%endrep
lodsb ; No shift needed for final cell
or ax,bx
stosw ; Store word in CGA memory
loop .word ; Do next byte of line
add si,HSIZE ; Even and odd lines stored separately
cmp si,FSIZE ; Done yet?
jb .line ; If not, do next line
add dx,200h ; Move to next segment
cmp dx,CGASEG+200h ; If we still need to do the odd lines,
mov si,HSIZE ; then do them
jbe .scrn
;;; Stop the program if a key is pressed
mov ah,1 ; Check if a key is pressed
int 16h
jz calc ; If not, calculate next field state
pop ax ; Otherwise, restore the old video mode,
cbw
int 10h
mov ah,exit ; and exit to DOS.
int 21h
;;; Calculate next field state
calc: mov ax,ds ; Set ES = new field segment
add ax,FPARA
mov es,ax
xor di,di ; Start at beginning
xor si,si
.cell: lodsb ; Get cell
dec al ; A=1 = tree
jz .tree
dec al ; A=2 = fire
jz .fire
call rand16 ; An empty space fills with a tree
cmp ax,probP ; with probability P.
jc .mtree ; Otherwise it stays empty
.fire: xor al,al ; A burning tree turns into an empty cell
stosb
jmp .cnext
.mtree: mov al,TREE
stosb
.cnext: cmp si,FSIZE ; Are we there yet?
jne .cell ; If not, do next cell
push es ; Done - set ES=old field, DS=new field,
push ds
pop es
pop ds
mov cx,FSIZE/2
xor si,si
xor di,di
rep movsw ; copy the new field to the old field,
push es ; set DS to be the field to draw,
pop ds
xor di,di ; Instead of doing edge case handling in the
xor ax,ax ; Moore neighbourhood calculation, just zero
mov cx,HSIZE/2 ; out the borders for a slightly smaller image
rep stosw ; Upper border,
mov di,FSIZE-HSIZE
mov cx,HSIZE/2
rep stosw ; lower border,
mov di,HSIZE-5 ; right border.
mov cx,VSIZE-1
.bordr: stosb
add di,HSIZE-1
loop .bordr
jmp disp ; and update the display.
.tree: mov ax,[si-HSIZE-2] ; Load Moore neighbourhood
or al,[si-HSIZE]
or ax,[si-2]
or al,[si]
or ax,[si+HSIZE-2]
or al,[si+HSIZE]
or al,ah
test al,FIRE ; Are any of the trees on fire?
jnz .tburn ; Then set this tree on fire too
call rand16 ; Otherwise, spontaneous combustion?
cmp ax,probF
jc .tburn
mov al,TREE ; If not, the tree remains a tree
stosb
jmp .cnext
.tburn: mov al,FIRE ; Set the tree on fire
stosb
jmp .cnext
;;; Get a random word in AX
rand16: call random
xchg al,ah
;;; Get a random byte in AL. BX and DX destroyed.
random: mov bx,[cs:rnddat] ; BL=X BH=A
mov dx,[cs:rnddat+2] ; DL=B DH=C
inc bl ; X++
xor bh,dh ; A ^= C
xor bh,bl ; A ^= X
add dl,bh ; B += A
mov al,dl ; C' = B
shr al,1 ; C' >>= 1
add al,dh ; C' += C
xor al,bh ; C' ^= A
mov dh,al ; C = C'
mov [cs:rnddat+2],dx ; Update RNG state
mov [cs:rnddat],bx
ret
section .data
errcga: db 'CGA mode not supported.$'
errmem: db 'Not enough memory.$'
section .bss
rnddat: resb 4 ; RNG state
stack: resw 128 ; Stack space
.top: equ $
Ada
with Ada.Numerics.Float_Random; use Ada.Numerics.Float_Random;
with Ada.Text_IO; use Ada.Text_IO;
procedure Forest_Fire is
type Cell is (Empty, Tree, Fire);
type Board is array (Positive range <>, Positive range <>) of Cell;
procedure Step (S : in out Board; P, F : Float; Dice : Generator) is
function "+" (Left : Boolean; Right : Cell) return Boolean is
begin
return Left or else Right = Fire;
end "+";
function "+" (Left, Right : Cell) return Boolean is
begin
return Left = Fire or else Right = Fire;
end "+";
Above : array (S'Range (2)) of Cell := (others => Empty);
Left_Up, Up, Left : Cell;
begin
for Row in S'First (1) + 1..S'Last (1) - 1 loop
Left_Up := Empty;
Up := Empty;
Left := Empty;
for Column in S'First (2) + 1..S'Last (2) - 1 loop
Left_Up := Up;
Up := Above (Column);
Above (Column) := S (Row, Column);
case S (Row, Column) is
when Empty =>
if Random (Dice) < P then
S (Row, Column) := Tree;
end if;
when Tree =>
if Left_Up + Up + Above (Column + 1) +
Left + S (Row, Column) + S (Row, Column + 1) +
S (Row + 1, Column - 1) + S (Row + 1, Column) + S (Row + 1, Column + 1)
or else Random (Dice) < F then
S (Row, Column) := Fire;
end if;
when Fire =>
S (Row, Column) := Empty;
end case;
Left := Above (Column);
end loop;
end loop;
end Step;
procedure Put (S : Board) is
begin
for Row in S'First (1) + 1..S'Last (1) - 1 loop
for Column in S'First (2) + 1..S'Last (2) - 1 loop
case S (Row, Column) is
when Empty => Put (' ');
when Tree => Put ('Y');
when Fire => Put ('#');
end case;
end loop;
New_Line;
end loop;
end Put;
Dice : Generator;
Forest : Board := (1..10 => (1..40 => Empty));
begin
Reset (Dice);
for I in 1..10 loop
Step (Forest, 0.3, 0.1, Dice);
Put_Line ("-------------" & Integer'Image (I) & " -------------");
Put (Forest);
end loop;
end Forest_Fire;
Sample output:
------------- 1 -------------
Y Y Y Y YY Y Y Y Y Y
Y Y YYY YY Y Y Y Y Y
Y YY Y Y Y Y Y Y Y Y YY
Y Y Y Y YY
Y YY YYY Y Y Y Y Y
Y Y YY Y Y Y Y
Y Y Y Y Y Y Y Y
Y Y Y YYY Y Y Y Y Y
------------- 2 -------------
Y Y Y YYYYY# YYY Y Y Y YYY Y Y Y
YY# YYY YY Y Y Y Y #Y Y YY Y
YYY YY Y YY# Y YY Y Y Y Y YY
Y Y YY Y Y YYYY Y Y YYY YY
Y Y Y#Y YYY YYYY YYY Y Y Y
Y Y Y Y YYY Y# Y Y Y Y Y
Y Y Y# Y Y Y Y Y YYY Y
YY YY Y Y YYY YYYYY Y Y YY Y
------------- 3 -------------
YY # Y YYYY# YY# Y Y # YYY Y# Y Y
Y# Y YYYYY Y# # YYY YYY #YY Y YY Y
Y## Y#Y Y Y# YY YY YY # Y Y YYY
# Y Y## # YYYYYY YYY YYYYYY YY
Y Y YY # # YY# #YYYYYY YYYYY YY# Y
YYY YYY Y# #YYY# YYY Y YY Y
Y YY Y # Y# Y YY YYY Y YYYYY
YY #Y YYY Y ### YYYY# YY YYYYY YY
------------- 4 -------------
## Y YY## Y ## Y YYY Y YYY # Y Y
# Y# ###YYY# Y ### YYYY #Y Y Y## Y
# # # # # #YYYY Y# Y# YYYYYYYY
Y YY YY# YY Y ##YYYY ##Y YYYYY#Y#Y
YY#YYY Y Y Y# Y #YYYYYY YYYYY Y# Y
YY#YYY#Y# ### Y YY #YY Y YY # Y
#Y ## # Y# YYY# ##Y Y YYYYY Y
YYY #YYY# YYY YYY# YYYYY#YY YY
------------- 5 -------------
Y # Y# Y #YYYYY #Y#YYY Y# Y
Y# Y ### Y Y###Y # Y # Y
Y Y Y Y #### # # #YY#####
# ## ## Y##Y# #Y##Y # YYYY# # #
Y# #Y#YY#Y#Y # YY ####Y# ##YYYY # #
Y# ### # Y # ##Y ##Y# YY Y Y
Y # # Y## # Y ###Y# Y
Y## ### YYY Y Y## #YYY# #Y YYY
------------- 6 -------------
Y# YY # Y Y #####Y # #Y#Y # Y
# Y#Y Y YY YYY# #Y #Y Y #
# # # # Y ##
Y# # Y # # Y ####
# Y # ## # #Y ## Y # Y #YYY Y
# Y#YYYY # # Y ##YY# #
Y # Y Y Y Y# Y # Y Y
# Y Y YY# YY Y# #Y# Y #Y#YY
------------- 7 -------------
Y# Y YY Y Y # Y # #Y Y#
# # YY # YY YY## Y #Y #Y #Y
Y Y Y Y #Y Y YY Y Y
Y Y # Y Y YY YYY Y
YY # YY Y # ###Y #
Y # ####YY YY # ##
Y# Y Y # # Y # YY Y#Y # #
Y # Y Y# YYYY# Y # YY # #Y
------------- 8 -------------
# # #Y Y Y YYYY Y Y Y # #
YYY YY Y ## Y# Y Y Y # Y #Y #Y
Y #Y Y#YY #Y # #Y Y YY #Y
Y Y # YYYYYY Y##Y Y Y Y
YYYY Y Y Y YYY Y Y Y Y # YY
# YY YY Y ##Y YYY##Y YYY
# Y Y Y #Y YY#Y # # Y YY
#Y Y YYY# # YY### Y YYY #
------------- 9 -------------
Y # YY YY####Y# YYYYYY # Y
### ## # Y # # Y Y YY # #
Y #Y # #Y Y Y # # Y# #Y Y # Y
# # YYYY ######YY# # Y Y# YY
###Y YY YYY # ### YY# # YY YY
YYY YY Y Y # Y ### # ### Y YY
Y Y Y Y Y #Y Y# #Y Y Y#
# Y YY# Y# # Y #Y# YY
------------- 10 -------------
YYYY ## Y# # ##YYYYY Y#
Y Y Y Y# # YYY YY
#Y # # # Y Y Y # Y # YYYY Y#
Y Y###Y ## Y Y# Y# #Y
# ## YYY Y## ## YY YY
##Y YY YYY# Y Y# #Y
# Y # Y Y # # # # # #
Y YYY# # YY Y # #Y
ALGOL 68
Textual version
Note: This specimen retains the original D coding style.
LONG REAL tree prob = 0.55, # original tree probability #
f prob = 0.01, # new combustion probability #
p prob = 0.01; # tree creation probability #
MODE CELL = CHAR; CELL empty=" ", tree="T", burning="#";
MODE WORLD = [6, 65]CELL;
PROC has burning neighbours = (WORLD world, INT r, c)BOOL:(
FOR row shift FROM -1 TO 1 DO
FOR col shift FROM -1 TO 1 DO
INT rs = r + row shift, cs = c + col shift;
IF rs >= LWB world AND rs <= UPB world AND
cs >= 2 LWB world AND cs <= 2 UPB world THEN
IF world[rs, cs] = burning THEN true exit FI
FI
OD
OD;
FALSE EXIT
true exit: TRUE
);
PROC next state = (REF WORLD world, REF WORLD next world)VOID:(
FOR r FROM LWB world TO UPB world DO
REF[]CELL row = world[r, ];
FOR c FROM LWB row TO UPB row DO
REF CELL elem = row[c];
next world[r, c] :=
IF elem = empty THEN
IF random<p prob THEN tree ELSE empty FI
ELIF elem = tree THEN
IF has burning neighbours(world, r, c) THEN
burning
ELSE
IF random<f prob THEN burning ELSE tree FI
FI
ELIF elem = burning THEN
empty
FI
OD
OD;
world := next world
);
main:(
WORLD world; # create world #
FOR r FROM LWB world TO UPB world DO
REF []CELL row = world[r, ];
FOR i FROM LWB row TO UPB row DO
REF CELL el = row[i];
el := IF random < tree prob THEN tree ELSE empty FI
OD
OD;
WORLD next world;
FOR i FROM 0 TO 4 DO
next state(world, next world);
printf(($n(2 UPB world)(a)l$, world)); # show world #
printf(($gl$, 2 UPB world * "-"))
OD
)Output:
TTTT T TTTT TT T T TTT TT TTT TT TTT T TT T T TTT TT T TT TTT TTTTT T T T TTTT T T TTT TT T T TT T T T TTT T T T T T T TT T # T T TTT T T T TTTTT T TTT TTTT TTTT TT T TT TTTTTTTTT TT TT T T TT T TT TTT TTT TTTT TT TTT TT TTTTTT T T T T T T TT TT TT #T TTT TT #TTTTTTTT TT TTT TTTTTTTTTT TT TTTTTT TT T TT T TTT T TT T TT # T T ----------------------------------------------------------------- TTTT T TTTT TT T T TTT TT TTT TT TTT T TT T T TTT TT T TT TTT TTTTT T T T ##TT T T TTT TT T T TT T T T TTT T T T T T T TT T T T TTT T T T TTTTT T TTT TTTT TTTT TT T T# TTTTTTT## TT TT T T TT T T# #TT TTT T### TT TTT TT TTTTTT T T T T T T TT TT TTT # TTT TT #TTTTTTT TT TTT TTTTTTTTTT TT TTTTTT TT T TT T TTT # TT T TT T T ----------------------------------------------------------------- TTTT T TTTT TT T T ### TT TTT TT TTT T TT T T TTT TT T TT TTT TTTTT T T T #T T T TTT TT T T TT T T T TT# T T T T T T ## T T T TTT T T T ##### T TT# ##TT TTTT TT T # TTTTTT# TT TT T T TT TT # #T TTT # TT TTT TT T#T### T T # T T T TT TT TT# TTT T# #TTTTTT TT TTT TTTTTTTTTT TT TTTTTT TT T TT T TTT #T T TTT T T ----------------------------------------------------------------- TTTT T TTTT TT T T #T TTT TT TTT T TT T T TTT TT # TT TTT TTTT# # T # # T T TTT TT # # ## T # # ## T T T T T T T # T TTT T T T T T# ## TTTT TT # #TTTT# TT TT T T TT TT # TTT #T TTT TT # # T # T T T TT TT T# #TT # #TTTTT TT TTT ######TTTT T# #TTTTT TT T TT T T## # T ### # T ----------------------------------------------------------------- #TTT T T### ## T # # TTT TT TTT T ## # # ### ## TT TTT TTT# T T T TTT TT T T T T T # # T T TTT T T T T# # TTTT TT #TT# ## TT T T TT T# TT# # TTT TT T # T T TT TT # #T #TTTT TT TT# #TT# # #TTTT TT T TT T # T T -----------------------------------------------------------------
AutoHotkey
This implementation uses AutoHotkey's pseudo-arrays to contain each cell. The size of the (square) map, probabilities, and characters which correspond to burning, tree, or empty can be edited at the beginning of the script.
; The array Frame1%x%_%y% holds the current frame. frame2%x%_%y%
; is then calculated from this, and printed. frame2 is then copied to frame1.
; Two arrays are necessary so that each cell advances at the same time
; T=Tree, #=Fire, O=Empty cell
; Size holds the width and height of the map and is used as the # of iterations in loops
; This will save the map as forest_fire.txt in its working directory
; ======================================================================================
Size := 10
Generation := 0
Tree := "T"
Fire := "#"
Cell := "O"
; --Define probabilities--
New_Tree := 5
; 20 percent chance (1 in 5). A random number will be generated from 1 to New_tree. If this number is 1,
; A tree will be created in the current cell
Spontaneous := 10
; 10 percent chance (1 in 10). A random number will be generated from 1 to Spontaneous. If this number is 1,
; and the current cell contains a tree, the tree in the current cell will become fire.
GoSub, Generate
; ----------------------Main Loop------------------------------
loop
{
Generation++
GoSub, Calculate
GoSub, Copy
GoSub, Display
msgbox, 4, Forest Fire, At Generation %generation%. Continue?
IfMsgbox, No
ExitApp
}
return
; -------------------------------------------------------------
Generate: ; Randomly initializes the map.
loop % size ; % forces expression mode.
{
x := A_Index
Loop % size
{
Y := A_Index
Random, IsTree, 1, 2 ; -- Roughly half of the spaces will contain trees
If ( IsTree = 1 )
Frame1%x%_%y% := Tree
Else
Frame1%x%_%y% := Cell
}
}
return
Calculate:
Loop % size
{
x := A_Index
Loop % size
{
Y := A_Index
If ( Frame1%x%_%y% = Cell )
{
Random, tmp, 1, New_Tree
If ( tmp = 1 )
Frame2%x%_%y% := tree
Else
Frame2%x%_%y% := Cell
}
Else If ( Frame1%x%_%y% = Tree )
{
BoolCatch := PredictFire(x,y)
If (BoolCatch)
Frame2%x%_%y% := Fire
Else
Frame2%x%_%y% := Tree
}
Else If ( Frame1%x%_%y% = Fire )
Frame2%x%_%y% := Cell
Else
{
contents := Frame1%x%_%y%
Msgbox Error! Cell %x% , %y% contains %contents% ; This has never happened
ExitApp
}
}
}
return
Copy:
Loop % size
{
x := A_Index
Loop % size
{
y := A_Index
frame1%x%_%y% := Frame2%x%_%y%
}
}
return
Display:
ToPrint := ""
ToPrint .= "=====Generation " . Generation . "=====`n"
Loop % size
{
x := A_Index
Loop % size
{
y := A_Index
ToPrint .= Frame1%x%_%y%
}
ToPrint .= "`n"
}
FileAppend, %ToPrint%, Forest_Fire.txt
Return
PredictFire(p_x,p_y){
Global ; allows access to all frame1*_* variables (the pseudo-array)
A := p_x-1
B := p_y-1
C := p_x+1
D := p_y+1
If ( Frame1%A%_%p_Y% = fire )
return 1
If ( Frame1%p_X%_%B% = fire )
return 1
If ( Frame1%C%_%p_Y% = fire )
return 1
If ( Frame1%p_X%_%D% = fire )
return 1
If ( Frame1%A%_%B% = Fire )
return 1
If ( Frame1%A%_%D% = fire )
return 1
If ( Frame1%C%_%B% = fire )
return 1
If ( Frame1%C%_%D% = Fire )
return 1
Random, tmp, 1, spontaneous
if ( tmp = 1 )
return 1
return 0
}
Sample Output using the default settings:
=====Generation 1===== OTTTOOTOOT OTOOTTTTOT TTOOOTTTO# TOOTOTOOTT OTTOTOOTTO TOTTTTOOTO TOTTT#OOOT OT#OOTOOTT TTO#TOOTTT O#OOOTOTTT =====Generation 2===== OTTTOOTOOT OTTOTTT#O# TTOOOTTTOO TOOTTTOT## OTTOTTO##O TOTT##OTTO TO###OOOOT T#OOO#OOTT ##TO#OOTTT TOTOOTOTTT =====Generation 3===== OTT#OO#TO# OTTOTT#OTO TTOOOT##OO TOOTTTT#OO OTTO##OOOO TO##OOO##O #OOOOOOOOT #OOOOOOOTT OO#OOTOTTT #O#TT#OTTT =====Generation 4===== OT#OOOO#OO OT#O##OO#T T#TOT#OOOO TOO####OOT O##OOOOOOO #OOOOOOOOO OOOOOOOOO# OTOOOOOOTT OOOOO#TTTT OTO##OO#TT =====Generation 5===== O#OOOTOOOT O#OOOOOOO# #O#O#OOTOT #OOOOOOOOT OOOOOOOOOO OTOOOOOOOO TTOOOTOTTO TTOOOTOO## OOTTOO###T OTOOOOOO#T
BASIC
Applesoft BASIC
100 FOR I = 17239 TO 17493
110 READ B
120 POKE I,B
130 NEXT
140 CALL 17239
150 END
160 DATA162,23,138,32,71,248,165,38,157,60,3,165,39,157,84,3,202,16,239,162,96
170 DATA134,249,134,1,160,0,132,0,152,145,0,200,208,251,232,134,1,224,128,208
180 DATA244,44,86,192,44,82,192,44,84,192,44,80,192,32,50,248,162,0,134,0,169
190 DATA41,133,2,133,254,169,83,133,4,165,249,133,1,133,3,133,5,73,16,133,255
200 DATA133,249,138,134,45,74,168,169,15,144,2,105,224,133,46,185,60,3,133,38
210 DATA185,84,3,133,39,160,1,132,44,177,2,145,254,240,79,16,93,169,0,164,44
220 DATA145,254,136,81,38,37,46,81,38,145,38,164,44,200,192,41,208,224,165,2
230 DATA133,0,165,3,133,1,165,4,133,2,133,254,24,105,42,133,4,165,5,73,16
240 DATA133,255,73,16,133,3,105,0,133,5,166,45,232,224,48,208,159,44,0,192
250 DATA48,3,76,144,67,44,16,192,44,81,192,96,198,8,208,190,169,101,133,8,169
260 DATA68,208,169,169,153,208,165,198,6,208,14,198,7,208,10,169,23,133,6,169
270 DATA39,133,7,208,234,177,0,17,4,136,17,0,17,2,17,4,200,200,17,0,17,2,17,4
280 DATA48,213,16,137,41
BASIC256
N = 150 : M = 150 : P = 0.03 : F = 0.00003
dim f(N+2,M+2) # 1 tree, 0 empty, 2 fire
dim fn(N+2,M+2)
graphsize N,M
fastgraphics
for x = 1 to N
for y = 1 to M
if rand<0.5 then f[x,y] = 1
next y
next x
while True
for x = 1 to N
for y = 1 to M
if not f[x,y] and rand<P then fn[x,y]=1
if f[x,y]=2 then fn[x,y]=0
if f[x,y]=1 then
fn[x,y] = 1
if f[x-1,y-1]=2 or f[x,y-1]=2 or f[x+1,y-1]=2 then fn[x,y]=2
if f[x-1,y]=2 or f[x+1,y]=2 or rand<F then fn[x,y]=2
if f[x-1,y+1]=2 or f[x,y+1]=2 or f[x+1,y+1]=2 then fn[x,y]=2
end if
# Draw
if fn[x,y]=0 then color black
if fn[x,y]=1 then color green
if fn[x,y]=2 then color yellow
plot x-1,y-1
next y
next x
refresh
for x = 1 to N
for y = 1 to M
f[x,y] = fn[x,y]
next y
next x
end whileBBC BASIC
VDU 23,22,400;400;16,16,16,128
OFF
DIM old&(200,200), new&(200,200)
p = 0.01
f = 0.0001
REM 0 = empty, 1 = tree, 2 = burning
REPEAT
WAIT 10
FOR x% = 1 TO 199
FOR y% = 1 TO 199
CASE old&(x%,y%) OF
WHEN 0:
IF p > RND(1) THEN
new&(x%,y%) = 1
GCOL 2
PLOT 4*x%,4*y%
ENDIF
WHEN 1:
IF f > RND(1) OR old&(x%-1,y%)=2 OR old&(x%+1,y%)=2 OR \
\ old&(x%-1,y%-1)=2 OR old&(x%,y%-1)=2 OR old&(x%+1,y%-1)=2 OR \
\ old&(x%-1,y%+1)=2 OR old&(x%,y%+1)=2 OR old&(x%+1,y%+1)=2 THEN
new&(x%,y%) = 2
GCOL 1
PLOT 4*x%,4*y%
ENDIF
WHEN 2:
new&(x%,y%) = 0
GCOL 15
PLOT 4*x%,4*y%
ENDCASE
NEXT
NEXT x%
old&() = new&()
UNTIL FALSE
Output:
Commodore BASIC
With the keyword CALL changed to SYS, the Applesoft BASIC code works in Commodore BASIC.
100 FOR I = 17239 TO 17493
110 READ B
120 POKE I,B
130 NEXT
140 SYS 17239
150 END
160 DATA162,23,138,32,71,248,165,38,157,60,3,165,39,157,84,3,202,16,239,162,96
170 DATA134,249,134,1,160,0,132,0,152,145,0,200,208,251,232,134,1,224,128,208
180 DATA244,44,86,192,44,82,192,44,84,192,44,80,192,32,50,248,162,0,134,0,169
190 DATA41,133,2,133,254,169,83,133,4,165,249,133,1,133,3,133,5,73,16,133,255
200 DATA133,249,138,134,45,74,168,169,15,144,2,105,224,133,46,185,60,3,133,38
210 DATA185,84,3,133,39,160,1,132,44,177,2,145,254,240,79,16,93,169,0,164,44
220 DATA145,254,136,81,38,37,46,81,38,145,38,164,44,200,192,41,208,224,165,2
230 DATA133,0,165,3,133,1,165,4,133,2,133,254,24,105,42,133,4,165,5,73,16
240 DATA133,255,73,16,133,3,105,0,133,5,166,45,232,224,48,208,159,44,0,192
250 DATA48,3,76,144,67,44,16,192,44,81,192,96,198,8,208,190,169,101,133,8,169
260 DATA68,208,169,169,153,208,165,198,6,208,14,198,7,208,10,169,23,133,6,169
270 DATA39,133,7,208,234,177,0,17,4,136,17,0,17,2,17,4,200,200,17,0,17,2,17,4
280 DATA48,213,16,137,41
FreeBASIC
'[RC] Forest Fire
'written for FreeBASIC
'Program code based on BASIC256 from Rosettacode website
'http://rosettacode.org/wiki/Forest_fire#BASIC256
'06-10-2016 updated/tweaked the code
'compile with fbc -s gui
#Define M 400
#Define N 640
Dim As Double p = 0.003
Dim As Double fire = 0.00003
'Dim As Double number1
Dim As Integer gen, x, y
Dim As String press
'f0() and fn() use memory from the memory pool
Dim As UByte f0(), fn()
ReDim f0(-1 To N +2, -1 To M +2)
ReDim fn(-1 To N +2, -1 To M +2)
Dim As UByte white = 15 'color 15 is white
Dim As UByte yellow = 14 'color 14 is yellow
Dim As UByte black = 0 'color 0 is black
Dim As UByte green = 2 'color 2 is green
Dim As UByte red = 4 'color 4 is red
Screen 18 'Resolution 640x480 with at least 256 colors
Randomize Timer
Locate 28,1
Beep
Print " Welcome to Forest Fire"
Locate 29,1
Print " press any key to start"
Sleep
'Locate 28,1
'Print " Welcome to Forest Fire"
Locate 29,1
Print " "
' 1 tree, 0 empty, 2 fire
Color green ' this is green color for trees
For x = 1 To N
For y = 1 To M
If Rnd < 0.5 Then 'populate original tree density
f0(x,y) = 1
PSet (x,y)
End If
Next y
Next x
Color white
Locate 29,1
Print " Press any key to continue "
Sleep
Locate 29,1
Print " Press 'space bar' to continue/pause, ESC to stop "
Do
press = InKey
ScreenLock
For x = 1 To N
For y = 1 To M
If Not f0(x,y) And Rnd<P Then fn(x,y)=1
If f0(x,y)=2 Then fn(x,y)=0
If f0(x,y)=1 Then
fn(x,y) = 1
If f0(x-1,y-1)=2 OrElse f0(x,y-1)=2 OrElse f0(x+1,y-1)=2 Then fn(x,y)=2
If f0(x-1,y)=2 OrElse f0(x+1,y)=2 OrElse Rnd<fire Then fn(x,y)=2
If f0(x-1,y+1)=2 OrElse f0(x,y+1)=2 OrElse f0(x+1,y+1)=2 Then fn(x,y)=2
End If
'set up color and drawing
'0 empty (black), 1 tree (green), 2 fire (white)
If fn(x,y)=0 Then Color black 'empty
If fn(x,y)=1 Then Color green 'tree
If fn(x,y)=2 Then Color red 'fire
'plot x-1,y-1
PSet (x-1,y-1)
Next y
Next x
'print generation number
gen = gen + 1
Locate 28,1
Color white 'this is white color
Print " Generation number # ";gen
'transfer new generation to current generation
For x = 1 To N
For y = 1 To M
f0(x,y) = fn(x,y)
Next y
Next x
ScreenUnlock
' amount for sleep is in milliseconds, 1 = ignore key press
Sleep 50, 1 ' slow down a little ... goes too fast otherwise
If press = " " Then Sleep : press = InKey
If press = "s" Then Sleep
' return to do loop up top until "esc" key is pressed.
' clicking close windows "X", closes the window immediately
Loop Until press = Chr(27) OrElse press = Chr(255)+"k"
If press = Chr(255) + "k" Then End
Locate 28,1
Color white
Print " You entered ESC - goodbye "
Print " Press any key to exit "
Sleep
GFA Basic
width%=80
height%=50
DIM world%(width%+2,height%+2,2)
clock%=0
'
empty%=0 ! some mnemonic codes for the different states
burning%=1
tree%=2
'
f=0.0003
p=0.03
max_clock%=100
'
@open_window
@setup_world
DO
clock%=clock%+1
EXIT IF clock%>max_clock%
@display_world
@update_world
LOOP
@close_window
'
' Setup the world
'
PROCEDURE setup_world
LOCAL i%,j%
'
RANDOMIZE 0
ARRAYFILL world%(),empty%
' with Probability 0.5, create tree in cells
FOR i%=1 TO width%
FOR j%=1 TO height%
IF RND>0.5
world%(i%,j%,0)=tree%
ENDIF
NEXT j%
NEXT i%
'
cur%=0
new%=1
RETURN
'
' Display world on window
'
PROCEDURE display_world
LOCAL size%,i%,j%,offsetx%,offsety%,x%,y%
'
size%=5
offsetx%=10
offsety%=20
'
VSETCOLOR 0,15,15,15 ! colour for empty
VSETCOLOR 1,15,0,0 ! colour for burning
VSETCOLOR 2,0,15,0 ! colour for tree
VSETCOLOR 3,0,0,0 ! colour for text
DEFTEXT 3
PRINT AT(1,1);"Clock: ";clock%
'
FOR i%=1 TO width%
FOR j%=1 TO height%
x%=offsetx%+size%*i%
y%=offsety%+size%*j%
SELECT world%(i%,j%,cur%)
CASE empty%
DEFFILL 0
CASE tree%
DEFFILL 2
CASE burning%
DEFFILL 1
ENDSELECT
PBOX x%,y%,x%+size%,y%+size%
NEXT j%
NEXT i%
RETURN
'
' Check if a neighbour is burning
'
FUNCTION neighbour_burning(i%,j%)
LOCAL x%
'
IF world%(i%,j%-1,cur%)=burning%
RETURN TRUE
ENDIF
IF world%(i%,j%+1,cur%)=burning%
RETURN TRUE
ENDIF
FOR x%=-1 TO 1
IF world%(i%-1,j%+x%,cur%)=burning% OR world%(i%+1,j%+x%,cur%)=burning%
RETURN TRUE
ENDIF
NEXT x%
RETURN FALSE
ENDFUNC
'
' Update the world state
'
PROCEDURE update_world
LOCAL i%,j%
'
FOR i%=1 TO width%
FOR j%=1 TO height%
world%(i%,j%,new%)=world%(i%,j%,cur%)
SELECT world%(i%,j%,cur%)
CASE empty%
IF RND>1-p
world%(i%,j%,new%)=tree%
ENDIF
CASE tree%
IF @neighbour_burning(i%,j%) OR RND>1-f
world%(i%,j%,new%)=burning%
ENDIF
CASE burning%
world%(i%,j%,new%)=empty%
ENDSELECT
NEXT j%
NEXT i%
'
cur%=1-cur%
new%=1-new%
RETURN
'
' open and clear window
'
PROCEDURE open_window
OPENW 1
CLEARW 1
VSETCOLOR 4,8,8,0
DEFFILL 4
PBOX 0,0,500,400
RETURN
'
' close the window after keypress
'
PROCEDURE close_window
~INP(2)
CLOSEW 1
RETURN
PureBasic
; Some systems reports high CPU-load while running this code.
; This may likely be due to the graphic driver used in the
; 2D-function Plot().
; If experiencing this problem, please reduce the #Width & #Height
; or activate the parameter #UnLoadCPU below with a parameter 1 or 2.
;
; This code should work with the demo version of PureBasic on both PC & Linux
; General parameters for the world
#f = 1e-6
#p = 1e-2
#SeedATree = 0.005
#Width = 400
#Height = 400
; Setting up colours
#Fire = $080CF7
#BackGround = $BFD5D3
#YoungTree = $00E300
#NormalTree = $00AC00
#MatureTree = $009500
#OldTree = $007600
#Black = $000000
; Depending on your hardware, use this to control the speed/CPU-load.
; 0 = No load reduction
; 1 = Only active about every second frame
; 2 = '1' & release the CPU after each horizontal line.
#UnLoadCPU = 0
Enumeration
#Empty =0
#Ignited
#Burning
#Tree
#Old=#Tree+20
EndEnumeration
Global Dim Forest.i(#Width, #Height)
Global Title$="Forest fire in PureBasic"
Global Cnt
Macro Rnd()
(Random(2147483647)/2147483647.0)
EndMacro
Procedure Limit(n, min, max)
If n<min
n=min
ElseIf n>max
n=max
EndIf
ProcedureReturn n
EndProcedure
Procedure SpreadFire(x,y)
Protected cnt=0, i, j
For i=Limit(x-1, 0, #Width) To Limit(x+1, 0, #Width)
For j=Limit(y-1, 0, #Height) To Limit(y+1, 0, #Height)
If Forest(i,j)>=#Tree
Forest(i,j)=#Ignited
EndIf
Next
Next
EndProcedure
Procedure InitMap()
Protected x, y, type
For y=1 To #Height
For x=1 To #Width
If Rnd()<=#SeedATree
type=#Tree
Else
type=#Empty
EndIf
Forest(x,y)=type
Next
Next
EndProcedure
Procedure UpdateMap()
Protected x, y
For y=1 To #Height
For x=1 To #Width
Select Forest(x,y)
Case #Burning
Forest(x,y)=#Empty
SpreadFire(x,y)
Case #Ignited
Forest(x,y)=#Burning
Case #Empty
If Rnd()<=#p
Forest(x,y)=#Tree
EndIf
Default
If Rnd()<=#f
Forest(x,y)=#Burning
Else
Forest(x,y)+1
EndIf
EndSelect
Next
Next
EndProcedure
Procedure PresentMap()
Protected x, y, c
cnt+1
SetWindowTitle(0,Title$+", time frame="+Str(cnt))
StartDrawing(ImageOutput(1))
For y=0 To OutputHeight()-1
For x=0 To OutputWidth()-1
Select Forest(x,y)
Case #Empty
c=#BackGround
Case #Burning, #Ignited
c=#Fire
Default
If Forest(x,y)<#Tree+#Old
c=#YoungTree
ElseIf Forest(x,y)<#Tree+2*#Old
c=#NormalTree
ElseIf Forest(x,y)<#Tree+3*#Old
c=#MatureTree
ElseIf Forest(x,y)<#Tree+4*#Old
c=#OldTree
Else ; Tree died of old age
Forest(x,y)=#Empty
c=#Black
EndIf
EndSelect
Plot(x,y,c)
Next
CompilerIf #UnLoadCPU>1
Delay(1)
CompilerEndIf
Next
StopDrawing()
ImageGadget(1, 0, 0, #Width, #Height, ImageID(1))
EndProcedure
If OpenWindow(0, 10, 30, #Width, #Height, Title$, #PB_Window_MinimizeGadget)
SmartWindowRefresh(0, 1)
If CreateImage(1, #Width, #Height)
Define Event, freq
If ExamineDesktops() And DesktopFrequency(0)
freq=DesktopFrequency(0)
Else
freq=60
EndIf
AddWindowTimer(0,0,5000/freq)
InitMap()
Repeat
Event = WaitWindowEvent()
Select Event
Case #PB_Event_CloseWindow
End
Case #PB_Event_Timer
CompilerIf #UnLoadCPU>0
Delay(25)
CompilerEndIf
UpdateMap()
PresentMap()
EndSelect
ForEver
EndIf
EndIf
REALbasic
This example puts all of the forestry logic into a Thread class. This allows the UI to remain responsive while the Thread does all the work in the background. We create a Thread by subclassing the Thread object in the IDE, in this case creating forestfire as a subclass of the Thread object and put the following code in its Run() event:
Sub Run()
//Handy named constants
Const empty = 0
Const tree = 1
Const fire = 2
Const ablaze = &cFF0000 //Using the &c numeric operator to indicate a color in hex
Const alive = &c00FF00
Const dead = &c804040
//Our forest
Dim worldPic As New Picture(480, 480, 32)
Dim newWorld(120, 120) As Integer
Dim oldWorld(120, 120) As Integer
//Initialize forest
Dim rand As New Random
For x as Integer = 0 to 119
For y as Integer = 0 to 119
if rand.InRange(0, 2) = 0 Or x = 119 or y = 119 or x = 0 or y = 0 Then
newWorld(x, y) = empty
worldPic.Graphics.ForeColor = dead
worldPic.Graphics.FillRect(x*4, y*4, 4, 4)
Else
newWorld(x, y) = tree
worldPic.Graphics.ForeColor = alive
worldPic.Graphics.FillRect(x*4, y*4, 4, 4)
end if
Next
Next
oldWorld = newWorld
//Burn, baby burn!
While Window1.stop = False
For x as Integer = 0 To 119
For y As Integer = 0 to 119
Dim willBurn As Integer = rand.InRange(0, Window1.burnProb.Value)
Dim willGrow As Integer = rand.InRange(0, Window1.growProb.Value)
if x = 119 or y = 119 or x = 0 or y = 0 Then
Continue
end if
Select Case oldWorld(x, y)
Case empty
If willGrow = (Window1.growProb.Value) Then
newWorld(x, y) = tree
worldPic.Graphics.ForeColor = alive
worldPic.Graphics.FillRect(x*4, y*4, 4, 4)
end if
Case tree
if oldWorld(x - 1, y) = fire Or oldWorld(x, y - 1) = fire Or oldWorld(x + 1, y) = fire Or oldWorld(x, y + 1) = fire Or oldWorld(x + 1, y + 1) = fire Or oldWorld(x - 1, y - 1) = fire Or oldWorld(x - 1, y + 1) = fire Or oldWorld(x + 1, y - 1) = fire Or willBurn = (Window1.burnProb.Value) Then
newWorld(x, y) = fire
worldPic.Graphics.ForeColor = ablaze
worldPic.Graphics.FillRect(x*4, y*4, 4, 4)
end if
Case fire
newWorld(x, y) = empty
worldPic.Graphics.ForeColor = dead
worldPic.Graphics.FillRect(x*4, y*4, 4, 4)
End Select
Next
Next
Window1.Canvas1.Graphics.DrawPicture(worldPic, 0, 0)
oldWorld = newWorld
me.Sleep(Window1.speed.Value)
Wend
End SubAs you can see, this Thread is expecting a Window object called Window1 with several other objects within it. The IDE will automatically create a Window object called Window1 when a new GUI application is created. Our Window1 has 5 objects (widgets) in it: a Canvas (for displaying graphics), three sliders, and a pushbutton.
Sub Open()
//First method to run on the creation of a new Window. We instantiate an instance of our forestFire thread and run it.
Dim fire As New forestFire
fire.Run()
End Sub
stop As Boolean //a globally accessible property of Window1. Boolean properties default to False.
Sub Pushbutton1.Action()
stop = True
End Sub
Run BASIC
graphic #g, 200,200
dim preGen(200,200)
dim newGen(200,200)
for gen = 1 to 200
for x = 1 to 199
for y = 1 to 199
select case preGen(x,y)
case 0
if rnd(0) > .99 then newGen(x,y) = 1 : #g "color green ; set "; x; " "; y
case 2
newGen(x,y) = 0 : #g "color brown ; set "; x; " "; y
case 1
if preGen(x-1,y-1) = 2 or preGen(x-1,y) = 2 or preGen(x-1,y+1) = 2 _
or preGen(x,y-1) = 2 or preGen(x,y+1) = 2 or preGen(x+1,y-1) = 2 _
or preGen(x+1,y) = 2 or preGen(x+1,y+1) = 2 or rnd(0) > .999 then
#g "color red ; set "; x; " "; y
newGen(x,y) = 2
end if
end select
preGen(x-1,y-1) = newGen(x-1,y-1)
next y
next x
next gen
render #g
Sinclair ZX81 BASIC
Requires 16k of RAM.
In essence this is an enhanced version of my ZX Spectrum implementation (see below). The main improvement is that this version shows the ages of the trees: the age is represented using 0 to 9, then A to Z, followed theoretically by the special characters £$:?()><=+-*/;,. (in that order) and only then cycling back to 0. Realistically, no tree is likely to live that long.
The subroutine at line 1000 takes a number N and returns its inverse-video string representation as I$.
A couple of other notes on the listing:
(1) some characters need to be entered in Graphics mode, which is accessed using SHIFT9. I have represented this using square brackets: so if the listing says [ROSETTA CODE], you need to go into G mode and type ROSETTA CODE (which will be displayed on the ZX81 screen in inverse video). As a special case, [a] means for you to go into G mode and then type SHIFTA. The ZX81 character set does not include either square brackets or lower-case letters, so I hope this convention will not lead to too much confusion.
(2) this program differs from most BASIC examples on Rosetta Code, but resembles most real BASIC programs of more than about 20 lines, in that the line numbers do not always go up smoothly in multiples of ten.
10 DIM F$(20,30)
20 DIM N$(20,30)
30 LET INIT=.5
40 LET F=.02
50 LET P=.05
60 PRINT AT 0,1;"[FOREST FIRE FOR ROSETTA CODE]"
70 FOR I=0 TO 21
80 PRINT AT I,0;"[ ]"
90 PRINT AT I,31;"[ ]"
100 NEXT I
110 FOR I=1 TO 30
120 PRINT AT 21,I;"[ ]"
130 NEXT I
140 LET G=0
150 LET T=0
160 PRINT AT 21,1;"[GENERATION 0]"
170 PRINT AT 21,20;"[COVER]"
180 FOR I=1 TO 20
190 FOR J=1 TO 30
200 IF RND>=INIT THEN GOTO 240
210 PRINT AT I,J;"0"
220 LET F$(I,J)="0"
230 LET T=T+1
240 NEXT J
250 NEXT I
300 PRINT AT 21,26;"[ ]"
310 LET N=INT (.5+T/6)
320 GOSUB 1000
330 PRINT AT 21,26;I$;"[ PC]"
340 FOR I=1 TO 20
350 PRINT AT I,0;"[>]"
360 FOR J=1 TO 30
380 IF F$(I,J)<>"[a]" THEN GOTO 410
390 LET N$(I,J)=" "
400 GOTO 530
410 IF F$(I,J)<>" " THEN GOTO 433
420 IF RND<=P THEN LET N$(I,J)="0"
430 GOTO 530
433 LET N$(I,J)=CHR$ (1+CODE F$(I,J))
437 IF N$(I,J)>"Z" THEN LET N$(I,J)="£"
440 FOR K=I-1 TO I+1
450 FOR L=J-1 TO J+1
460 IF K=0 OR L=0 OR K=21 OR L=21 THEN GOTO 480
470 IF F$(K,L)="[a]" THEN GOTO 510
480 NEXT L
490 NEXT K
500 GOTO 520
510 LET N$(I,J)="[a]"
520 IF RND<=F THEN LET N$(I,J)="[a]"
530 NEXT J
540 PRINT AT I,0;"[ ]"
550 NEXT I
552 LET G=G+1
554 LET N=G
556 GOSUB 1000
558 PRINT AT 21,12;I$
560 LET T=0
570 FOR I=1 TO 20
575 PRINT AT I,31;"[<]"
580 FOR J=1 TO 30
590 IF N$(I,J)<>"[a]" AND N$(I,J)<>" " THEN LET T=T+1
600 NEXT J
610 LET F$(I)=N$(I)
620 PRINT AT I,1;F$(I)
625 PRINT AT I,31;"[ ]"
630 GOTO 300
1000 LET S$=STR$ N
1010 LET I$=""
1020 FOR K=1 TO LEN S$
1030 LET I$=I$+CHR$ (128+CODE S$(K))
1040 NEXT K
1050 RETURN
- Output:
Screenshot here.
Visual Basic .NET
This program sits behind a Windows form with fixed borders, the only component of which is a timer (named Timer1, set to something like 50 or 100ms depending on the speed the user wants to see it). Other constant values (the probabilities and the window dimensions) can be set at the top of the code.
Public Class ForestFire
Private _forest(,) As ForestState
Private _isBuilding As Boolean
Private _bm As Bitmap
Private _gen As Integer
Private _sw As Stopwatch
Private Const _treeStart As Double = 0.5
Private Const _f As Double = 0.00001
Private Const _p As Double = 0.001
Private Const _winWidth As Integer = 300
Private Const _winHeight As Integer = 300
Private Enum ForestState
Empty
Burning
Tree
End Enum
Private Sub ForestFire_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.ClientSize = New Size(_winWidth, _winHeight)
ReDim _forest(_winWidth, _winHeight)
Dim rnd As New Random()
For i As Integer = 0 To _winHeight - 1
For j As Integer = 0 To _winWidth - 1
_forest(j, i) = IIf(rnd.NextDouble <= _treeStart, ForestState.Tree, ForestState.Empty)
Next
Next
_sw = New Stopwatch
_sw.Start()
DrawForest()
Timer1.Start()
End Sub
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
If _isBuilding Then Exit Sub
_isBuilding = True
GetNextGeneration()
DrawForest()
_isBuilding = False
End Sub
Private Sub GetNextGeneration()
Dim forestCache(_winWidth, _winHeight) As ForestState
Dim rnd As New Random()
For i As Integer = 0 To _winHeight - 1
For j As Integer = 0 To _winWidth - 1
Select Case _forest(j, i)
Case ForestState.Tree
If forestCache(j, i) <> ForestState.Burning Then
forestCache(j, i) = IIf(rnd.NextDouble <= _f, ForestState.Burning, ForestState.Tree)
End If
Case ForestState.Burning
For i2 As Integer = i - 1 To i + 1
If i2 = -1 OrElse i2 >= _winHeight Then Continue For
For j2 As Integer = j - 1 To j + 1
If j2 = -1 OrElse i2 >= _winWidth Then Continue For
If _forest(j2, i2) = ForestState.Tree Then forestCache(j2, i2) = ForestState.Burning
Next
Next
forestCache(j, i) = ForestState.Empty
Case Else
forestCache(j, i) = IIf(rnd.NextDouble <= _p, ForestState.Tree, ForestState.Empty)
End Select
Next
Next
_forest = forestCache
_gen += 1
End Sub
Private Sub DrawForest()
Dim bmCache As New Bitmap(_winWidth, _winHeight)
For i As Integer = 0 To _winHeight - 1
For j As Integer = 0 To _winWidth - 1
Select Case _forest(j, i)
Case ForestState.Tree
bmCache.SetPixel(j, i, Color.Green)
Case ForestState.Burning
bmCache.SetPixel(j, i, Color.Red)
End Select
Next
Next
_bm = bmCache
Me.Refresh()
End Sub
Private Sub ForestFire_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
e.Graphics.DrawImage(_bm, 0, 0)
Me.Text = "Gen " & _gen.ToString() & " @ " & (_gen / (_sw.ElapsedMilliseconds / 1000)).ToString("F02") & " FPS: Forest Fire"
End Sub
End Class
ZX Spectrum Basic
This isn't a graphical implementation, but it uses a bit of colour to make the display clearer. It runs very slowly. The variable init defines the initial likelihood that each square will hold a tree, and can take values between 0 (no trees) and 1 (a tree in every square) inclusive. This can be used to check that the program is running correctly, and using a value of 1 is probably the most dramatic: but it only makes a difference in the short term. After a few generations, any starting configuration using these values of and will end up fluctuating around 20% tree cover—sparse woodland, perhaps, rather than true forest.
A screenshot of the program running can be found here.
10 PAPER 6: CLS
20 DIM n$(20,30)
30 LET init=.5
40 LET f=.02
50 LET p=.05
60 PAPER 0
70 FOR i=0 TO 31
80 PRINT AT 0,i;" "
90 PRINT AT 21,i;" "
100 NEXT i
110 FOR i=0 TO 21
120 PRINT AT i,0;" "
130 PRINT AT i,31;" "
140 NEXT i
150 INK 7
160 PRINT AT 0,1;"FOREST FIRE for Rosetta Code"
170 LET generation=0
180 PRINT AT 21,1;"Generation 0"
190 LET trees=0
200 PRINT AT 21,22;"Cover"
210 FOR i=1 TO 20
220 FOR j=1 TO 30
230 IF RND<init THEN PAPER 4: INK 7: PRINT AT i,j;"T": LET trees=trees+1
240 NEXT j
250 NEXT i
260 LET generation=generation+1
270 INK 7
280 PAPER 0
290 PRINT AT 21,12;generation
300 PRINT AT 21,28;" "
310 PRINT AT 21,28;INT (trees/6+.5);"%"
320 FOR i=1 TO 20
330 FOR j=1 TO 30
340 LET n$(i,j)=SCREEN$ (i,j)
350 IF SCREEN$ (i,j)="B" THEN LET n$(i,j)=" ": GO TO 450
360 IF SCREEN$ (i,j)="T" THEN GO TO 390
370 IF RND<=p THEN LET n$(i,j)="T"
380 GO TO 450
390 FOR k=i-1 TO i+1
400 FOR l=j-1 TO j+1
410 IF SCREEN$ (k,l)="B" THEN LET n$(i,j)="B": LET k=i+2: LET l=j+2
420 NEXT l
430 NEXT k
440 IF RND<=f THEN LET n$(i,j)="B"
450 NEXT j
460 NEXT i
470 LET trees=0
480 FOR i=1 TO 20
490 FOR j=1 TO 30
500 IF n$(i,j)="T" THEN INK 7: PAPER 4: PRINT AT i,j;"T": LET trees=trees+1: GO TO 540
510 IF n$(i,j)="B" THEN INK 6: PAPER 2: PRINT AT i,j;"B": GO TO 540
520 PAPER 6
530 PRINT AT i,j;" "
540 NEXT j
550 NEXT i
560 GO TO 260
Batch File
Accepts command line arguments in the form of m p f i
Where:
m - length and width of the array p - probability of a tree growing f - probability of a tree catching on fire i - iterations to output
Default is 10 50 5 5
@echo off
setlocal enabledelayedexpansion
if "%1"=="" (
call:default
) else (
call:setargs %*
)
call:createarray
call:fillarray
call:display
echo.
echo -------------------
echo.
for /l %%i in (1,1,%i%) do (
echo.
echo -------------------
echo.
call:evolve
call:display
)
pause>nul
:default
set m=10
set n=11
set p=50
set f=5
set i=5
exit /b
:setargs
set m=%1
set n=%m%+1
set p=%2
set f=%3
set i=%4
exit /b
:createarray
for /l %%m in (0,1,%n%) do (
for /l %%n in (0,1,%n%) do (
set a%%m%%n=0
)
)
exit /b
:fillarray
for /l %%m in (1,1,%m%) do (
for /l %%n in (1,1,%m%) do (
set /a treerandom=!random! %% 101
if !treerandom! leq %p% set a%%m%%n=T
)
)
exit /b
:display
for /l %%m in (1,1,%m%) do (
set "line%%m="
for /l %%n in (1,1,%m%) do (
set line%%m=!line%%m! !a%%m%%n!
)
set line%%m=!line%%m:0= !
echo.!line%%m!
)
exit /b
:evolve
for /l %%m in (1,1,%m%) do (
for /l %%n in (1,1,%m%) do (
call:nexttick !a%%m%%n! %%m %%n
set newa%%m%%n=!errorlevel!
)
)
call:update
exit /b
:nexttick
if %1==0 (
set /a treerandom=!random! %% 101
if !treerandom! leq %p% exit /b 1
exit /b 0
)
if %1==T (
set /a lowerm=%2-1
set /a upperm=%2+1
set /a lowern=%3-1
set /a uppern=%3+1
set burn=0
for /l %%m in (!lowerm!,1,!upperm!) do (
for /l %%n in (!lowern!,1,!uppern!) do (
if !a%%m%%n!==# set burn=1
)
)
if !burn!==1 exit /b 2
set /a burnrandom=!random! %% 101
if !burnrandom! leq %f% exit /b 2
exit /b 1
)
if %1==# exit /b 0
:update
for /l %%m in (1,1,%m%) do (
for /l %%n in (1,1,%m%) do (
if !newa%%m%%n!==1 set newa%%m%%n=T
if !newa%%m%%n!==2 set newa%%m%%n=#
set a%%m%%n=!newa%%m%%n!
)
)
exit /b
- Output:
Sample Default Output
T T T
T T T T T
T T T
T T T T T T T
T T T T
T T T T T T T
T T T T T
T T T T T
T T T T T T
T T T T T
-------------------
-------------------
T T # T T T #
T T T T T T T T
T T T T T T
T T T T T T T T T
T T T T T T
T T T T T T T T T T
T T T T T T T T T
T T T T T T
T T T T T T T T #
T T T T T T T
-------------------
T # # # #
T # # # T T T T # #
T T T T T T
T T T T T T T T T
T T T T T T T T
T T T T T # T T T T
T T T T T T T T #
T T T T T T # #
T T T T # T T T
# T T T T T #
-------------------
# T T
# # # # #
T # # # T # # #
T T T T T T T T T T
T T T T # # T T T
T T T T # # T # #
T T T T # # # # #
T T T # # #
# # T # # T # T T
T # # # T # T
-------------------
T T T T T T T
T
# #
T # # # # # # # # #
T # T # # T # #
T # T # #
T T T #
# # # T T
# # # T
T # # T
-------------------
T T T T T T T T
T T T T T
T T T
#
# # T #
# # T T
# # # T T T
# T #
T T T T #
# T T T #
C
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <pthread.h>
#include <SDL.h>
// defaults
#define PROB_TREE 0.55
#define PROB_F 0.00001
#define PROB_P 0.001
#define TIMERFREQ 100
#ifndef WIDTH
# define WIDTH 640
#endif
#ifndef HEIGHT
# define HEIGHT 480
#endif
#ifndef BPP
# define BPP 32
#endif
#if BPP != 32
#warning This program could not work with BPP different from 32
#endif
uint8_t *field[2], swapu;
double prob_f = PROB_F, prob_p = PROB_P, prob_tree = PROB_TREE;
enum cell_state {
VOID, TREE, BURNING
};
// simplistic random func to give [0, 1)
double prand()
{
return (double)rand() / (RAND_MAX + 1.0);
}
// initialize the field
void init_field(void)
{
int i, j;
swapu = 0;
for(i = 0; i < WIDTH; i++)
{
for(j = 0; j < HEIGHT; j++)
{
*(field[0] + j*WIDTH + i) = prand() > prob_tree ? VOID : TREE;
}
}
}
// the "core" of the task: the "forest-fire CA"
bool burning_neighbor(int, int);
pthread_mutex_t synclock = PTHREAD_MUTEX_INITIALIZER;
static uint32_t simulate(uint32_t iv, void *p)
{
int i, j;
/*
Since this is called by SDL, "likely"(*) in a separated
thread, we try to avoid corrupted updating of the display
(done by the show() func): show needs the "right" swapu
i.e. the right complete field. (*) what if it is not so?
The following is an attempt to avoid unpleasant updates.
*/
pthread_mutex_lock(&synclock);
for(i = 0; i < WIDTH; i++) {
for(j = 0; j < HEIGHT; j++) {
enum cell_state s = *(field[swapu] + j*WIDTH + i);
switch(s)
{
case BURNING:
*(field[swapu^1] + j*WIDTH + i) = VOID;
break;
case VOID:
*(field[swapu^1] + j*WIDTH + i) = prand() > prob_p ? VOID : TREE;
break;
case TREE:
if (burning_neighbor(i, j))
*(field[swapu^1] + j*WIDTH + i) = BURNING;
else
*(field[swapu^1] + j*WIDTH + i) = prand() > prob_f ? TREE : BURNING;
break;
default:
fprintf(stderr, "corrupted field\n");
break;
}
}
}
swapu ^= 1;
pthread_mutex_unlock(&synclock);
return iv;
}
// the field is a "part" of an infinite "void" region
#define NB(I,J) (((I)<WIDTH)&&((I)>=0)&&((J)<HEIGHT)&&((J)>=0) \
? (*(field[swapu] + (J)*WIDTH + (I)) == BURNING) : false)
bool burning_neighbor(int i, int j)
{
return NB(i-1,j-1) || NB(i-1, j) || NB(i-1, j+1) ||
NB(i, j-1) || NB(i, j+1) ||
NB(i+1, j-1) || NB(i+1, j) || NB(i+1, j+1);
}
// "map" the field into gfx mem
// burning trees are red
// trees are green
// "voids" are black;
void show(SDL_Surface *s)
{
int i, j;
uint8_t *pixels = (uint8_t *)s->pixels;
uint32_t color;
SDL_PixelFormat *f = s->format;
pthread_mutex_lock(&synclock);
for(i = 0; i < WIDTH; i++) {
for(j = 0; j < HEIGHT; j++) {
switch(*(field[swapu] + j*WIDTH + i)) {
case VOID:
color = SDL_MapRGBA(f, 0,0,0,255);
break;
case TREE:
color = SDL_MapRGBA(f, 0,255,0,255);
break;
case BURNING:
color = SDL_MapRGBA(f, 255,0,0,255);
break;
}
*(uint32_t*)(pixels + j*s->pitch + i*(BPP>>3)) = color;
}
}
pthread_mutex_unlock(&synclock);
}
int main(int argc, char **argv)
{
SDL_Surface *scr = NULL;
SDL_Event event[1];
bool quit = false, running = false;
SDL_TimerID tid;
// add variability to the simulation
srand(time(NULL));
// we can change prob_f and prob_p
// prob_f prob of spontaneous ignition
// prob_p prob of birth of a tree
double *p;
for(argv++, argc--; argc > 0; argc--, argv++)
{
if ( strcmp(*argv, "prob_f") == 0 && argc > 1 )
{
p = &prob_f;
} else if ( strcmp(*argv, "prob_p") == 0 && argc > 1 ) {
p = &prob_p;
} else if ( strcmp(*argv, "prob_tree") == 0 && argc > 1 ) {
p = &prob_tree;
} else continue;
argv++; argc--;
char *s = NULL;
double t = strtod(*argv, &s);
if (s != *argv) *p = t;
}
printf("prob_f %lf\nprob_p %lf\nratio %lf\nprob_tree %lf\n",
prob_f, prob_p, prob_p/prob_f,
prob_tree);
if ( SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER) != 0 ) return EXIT_FAILURE;
atexit(SDL_Quit);
field[0] = malloc(WIDTH*HEIGHT);
if (field[0] == NULL) exit(EXIT_FAILURE);
field[1] = malloc(WIDTH*HEIGHT);
if (field[1] == NULL) { free(field[0]); exit(EXIT_FAILURE); }
scr = SDL_SetVideoMode(WIDTH, HEIGHT, BPP, SDL_HWSURFACE|SDL_DOUBLEBUF);
if (scr == NULL) {
fprintf(stderr, "SDL_SetVideoMode: %s\n", SDL_GetError());
free(field[0]); free(field[1]);
exit(EXIT_FAILURE);
}
init_field();
tid = SDL_AddTimer(TIMERFREQ, simulate, NULL); // suppose success
running = true;
event->type = SDL_VIDEOEXPOSE;
SDL_PushEvent(event);
while(SDL_WaitEvent(event) && !quit)
{
switch(event->type)
{
case SDL_VIDEOEXPOSE:
while(SDL_LockSurface(scr) != 0) SDL_Delay(1);
show(scr);
SDL_UnlockSurface(scr);
SDL_Flip(scr);
event->type = SDL_VIDEOEXPOSE;
SDL_PushEvent(event);
break;
case SDL_KEYDOWN:
switch(event->key.keysym.sym)
{
case SDLK_q:
quit = true;
break;
case SDLK_p:
if (running)
{
running = false;
pthread_mutex_lock(&synclock);
SDL_RemoveTimer(tid); // ignore failure...
pthread_mutex_unlock(&synclock);
} else {
running = true;
tid = SDL_AddTimer(TIMERFREQ, simulate, NULL);
// suppose success...
}
break;
}
case SDL_QUIT:
quit = true;
break;
}
}
if (running) {
pthread_mutex_lock(&synclock);
SDL_RemoveTimer(tid);
pthread_mutex_unlock(&synclock);
}
free(field[0]); free(field[1]);
exit(EXIT_SUCCESS);
}
Console version
C99. Uncomment srand() for variaty, usleep() for slower speed.
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h> // For time
enum { empty = 0, tree = 1, fire = 2 };
const char *disp[] = {" ", "\033[32m/\\\033[m", "\033[07;31m/\\\033[m"};
double tree_prob = 0.01, burn_prob = 0.0001;
#define for_x for (int x = 0; x < w; x++)
#define for_y for (int y = 0; y < h; y++)
#define for_yx for_y for_x
#define chance(x) (rand() < RAND_MAX * x)
void evolve(int w, int h)
{
unsigned univ[h][w], new[h][w];
for_yx new[y][x] = univ[y][x] = chance(tree_prob) ? tree : empty;
show: printf("\033[H");
for_y {
for_x printf("%s",disp[univ[y][x]]);
printf("\033[E");
}
fflush(stdout);
for_yx {
switch (univ[y][x]) {
case fire: new[y][x] = empty;
break;
case empty: if (chance(tree_prob)) new[y][x] = tree;
break;
default:
for (int y1 = y - 1; y1 <= y + 1; y1++) {
if (y1 < 0 || y1 >= h) continue;
for (int x1 = x - 1; x1 <= x + 1; x1++) {
if (x1 < 0 || x1 >= w) continue;
if (univ[y1][x1] != fire) continue;
new[y][x] = fire;
goto burn;
}
}
burn:
if (new[y][x] == tree && chance(burn_prob))
new[y][x] = fire;
}
}
for_yx { univ[y][x] = new[y][x]; }
//usleep(100000);
goto show;
}
int main(int c, char **v)
{
//srand(time(0));
int w = 0, h = 0;
if (c > 1) w = atoi(v[1]);
if (c > 2) h = atoi(v[2]);
if (w <= 0) w = 30;
if (h <= 0) h = 30;
evolve(w, h);
}
C#
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Threading;
using System.Windows.Forms;
namespace ForestFire
{
class Program : Form
{
private static readonly Random rand = new Random();
private Bitmap img;
public Program(int w, int h, int f, int p)
{
Size = new Size(w, h);
StartPosition = FormStartPosition.CenterScreen;
Thread t = new Thread(() => fire(f, p));
t.Start();
FormClosing += (object sender, FormClosingEventArgs e) => { t.Abort(); t = null; };
}
private void fire(int f, int p)
{
int clientWidth = ClientRectangle.Width;
int clientHeight = ClientRectangle.Height;
int cellSize = 10;
img = new Bitmap(clientWidth, clientHeight);
Graphics g = Graphics.FromImage(img);
CellState[,] state = InitializeForestFire(clientWidth, clientHeight);
uint generation = 0;
do
{
g.FillRectangle(Brushes.White, 0, 0, img.Width, img.Height);
state = StepForestFire(state, f, p);
for (int y = 0; y < clientHeight - cellSize; y += cellSize)
{
for (int x = 0; x < clientWidth - cellSize; x += cellSize)
{
switch (state[y, x])
{
case CellState.Empty:
break;
case CellState.Tree:
g.FillRectangle(Brushes.DarkGreen, x, y, cellSize, cellSize);
break;
case CellState.Burning:
g.FillRectangle(Brushes.DarkRed, x, y, cellSize, cellSize);
break;
}
}
}
Thread.Sleep(500);
Invoke((MethodInvoker)Refresh);
} while (generation < uint.MaxValue);
g.Dispose();
}
private CellState[,] InitializeForestFire(int width, int height)
{
// Create our state array, initialize all indices as Empty, and return it.
var state = new CellState[height, width];
state.Initialize();
return state;
}
private enum CellState : byte
{
Empty = 0,
Tree = 1,
Burning = 2
}
private CellState[,] StepForestFire(CellState[,] state, int f, int p)
{
/* Clone our old state, so we can write to our new state
* without changing any values in the old state. */
var newState = (CellState[,])state.Clone();
int numRows = state.GetLength(0);
int numCols = state.GetLength(1);
for (int r = 1; r < numRows - 1; r++)
{
for (int c = 1; c < numCols - 1; c++)
{
/*
* Check the current cell.
*
* If it's empty, give it a 1/p chance of becoming a tree.
*
* If it's a tree, check to see if any neighbors are burning.
* If so, set the cell's state to burning, otherwise give it
* a 1/f chance of combusting.
*
* If it's burning, set it to empty.
*/
switch (state[r, c])
{
case CellState.Empty:
if (rand.Next(0, p) == 0)
newState[r, c] = CellState.Tree;
break;
case CellState.Tree:
if (NeighborHasState(state, r, c, CellState.Burning) || rand.Next(0, f) == 0)
newState[r, c] = CellState.Burning;
break;
case CellState.Burning:
newState[r, c] = CellState.Empty;
break;
}
}
}
return newState;
}
private bool NeighborHasState(CellState[,] state, int x, int y, CellState value)
{
// Check each cell within a 1 cell radius for the specified value.
for (int r = -1; r <= 1; r++)
{
for (int c = -1; c <= 1; c++)
{
if (r == 0 && c == 0)
continue;
if (state[x + r, y + c] == value)
return true;
}
}
return false;
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
e.Graphics.DrawImage(img, 0, 0);
}
[STAThread]
static void Main(string[] args)
{
Application.Run(new Program(w: 500, h: 500, f: 2, p: 5));
}
}
}
C++
#include <windows.h>
#include <string>
//--------------------------------------------------------------------------------------------------
using namespace std;
//--------------------------------------------------------------------------------------------------
enum states { NONE, TREE, FIRE };
const int MAX_SIDE = 500;
//--------------------------------------------------------------------------------------------------
class myBitmap
{
public:
myBitmap() : pen( NULL ) {}
~myBitmap()
{
DeleteObject( pen );
DeleteDC( hdc );
DeleteObject( bmp );
}
bool create( int w, int h )
{
BITMAPINFO bi;
ZeroMemory( &bi, sizeof( bi ) );
bi.bmiHeader.biSize = sizeof( bi.bmiHeader );
bi.bmiHeader.biBitCount = sizeof( DWORD ) * 8;
bi.bmiHeader.biCompression = BI_RGB;
bi.bmiHeader.biPlanes = 1;
bi.bmiHeader.biWidth = w;
bi.bmiHeader.biHeight = -h;
HDC dc = GetDC( GetConsoleWindow() );
bmp = CreateDIBSection( dc, &bi, DIB_RGB_COLORS, &pBits, NULL, 0 );
if( !bmp ) return false;
hdc = CreateCompatibleDC( dc );
SelectObject( hdc, bmp );
ReleaseDC( GetConsoleWindow(), dc );
width = w; height = h;
return true;
}
void clear()
{
ZeroMemory( pBits, width * height * sizeof( DWORD ) );
}
void setPenColor( DWORD clr )
{
if( pen ) DeleteObject( pen );
pen = CreatePen( PS_SOLID, 1, clr );
SelectObject( hdc, pen );
}
void saveBitmap( string path )
{
BITMAPFILEHEADER fileheader;
BITMAPINFO infoheader;
BITMAP bitmap;
DWORD wb;
GetObject( bmp, sizeof( bitmap ), &bitmap );
DWORD* dwpBits = new DWORD[bitmap.bmWidth * bitmap.bmHeight];
ZeroMemory( dwpBits, bitmap.bmWidth * bitmap.bmHeight * sizeof( DWORD ) );
ZeroMemory( &infoheader, sizeof( BITMAPINFO ) );
ZeroMemory( &fileheader, sizeof( BITMAPFILEHEADER ) );
infoheader.bmiHeader.biBitCount = sizeof( DWORD ) * 8;
infoheader.bmiHeader.biCompression = BI_RGB;
infoheader.bmiHeader.biPlanes = 1;
infoheader.bmiHeader.biSize = sizeof( infoheader.bmiHeader );
infoheader.bmiHeader.biHeight = bitmap.bmHeight;
infoheader.bmiHeader.biWidth = bitmap.bmWidth;
infoheader.bmiHeader.biSizeImage = bitmap.bmWidth * bitmap.bmHeight * sizeof( DWORD );
fileheader.bfType = 0x4D42;
fileheader.bfOffBits = sizeof( infoheader.bmiHeader ) + sizeof( BITMAPFILEHEADER );
fileheader.bfSize = fileheader.bfOffBits + infoheader.bmiHeader.biSizeImage;
GetDIBits( hdc, bmp, 0, height, ( LPVOID )dwpBits, &infoheader, DIB_RGB_COLORS );
HANDLE file = CreateFile( path.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL );
WriteFile( file, &fileheader, sizeof( BITMAPFILEHEADER ), &wb, NULL );
WriteFile( file, &infoheader.bmiHeader, sizeof( infoheader.bmiHeader ), &wb, NULL );
WriteFile( file, dwpBits, bitmap.bmWidth * bitmap.bmHeight * 4, &wb, NULL );
CloseHandle( file );
delete [] dwpBits;
}
HDC getDC() const { return hdc; }
int getWidth() const { return width; }
int getHeight() const { return height; }
private:
HBITMAP bmp;
HDC hdc;
HPEN pen;
void *pBits;
int width, height;
};
//--------------------------------------------------------------------------------------------------
class forest
{
public:
forest()
{
_bmp.create( MAX_SIDE, MAX_SIDE );
initForest( 0.05f, 0.005f );
}
void initForest( float p, float f )
{
_p = p; _f = f;
seedForest();
}
void mainLoop()
{
display();
simulate();
}
void setHWND( HWND hwnd ) { _hwnd = hwnd; }
private:
float probRand() { return ( float )rand() / 32768.0f; }
void display()
{
HDC bdc = _bmp.getDC();
DWORD clr;
for( int y = 0; y < MAX_SIDE; y++ )
{
for( int x = 0; x < MAX_SIDE; x++ )
{
switch( _forest[x][y] )
{
case FIRE: clr = 255; break;
case TREE: clr = RGB( 0, 255, 0 ); break;
default: clr = 0;
}
SetPixel( bdc, x, y, clr );
}
}
HDC dc = GetDC( _hwnd );
BitBlt( dc, 0, 0, MAX_SIDE, MAX_SIDE, _bmp.getDC(), 0, 0, SRCCOPY );
ReleaseDC( _hwnd, dc );
}
void seedForest()
{
ZeroMemory( _forestT, sizeof( _forestT ) );
ZeroMemory( _forest, sizeof( _forest ) );
for( int y = 0; y < MAX_SIDE; y++ )
for( int x = 0; x < MAX_SIDE; x++ )
if( probRand() < _p ) _forest[x][y] = TREE;
}
bool getNeighbors( int x, int y )
{
int a, b;
for( int yy = -1; yy < 2; yy++ )
for( int xx = -1; xx < 2; xx++ )
{
if( !xx && !yy ) continue;
a = x + xx; b = y + yy;
if( a < MAX_SIDE && b < MAX_SIDE && a > -1 && b > -1 )
if( _forest[a][b] == FIRE ) return true;
}
return false;
}
void simulate()
{
for( int y = 0; y < MAX_SIDE; y++ )
{
for( int x = 0; x < MAX_SIDE; x++ )
{
switch( _forest[x][y] )
{
case FIRE: _forestT[x][y] = NONE; break;
case NONE: if( probRand() < _p ) _forestT[x][y] = TREE; break;
case TREE: if( getNeighbors( x, y ) || probRand() < _f ) _forestT[x][y] = FIRE;
}
}
}
for( int y = 0; y < MAX_SIDE; y++ )
for( int x = 0; x < MAX_SIDE; x++ )
_forest[x][y] = _forestT[x][y];
}
myBitmap _bmp;
HWND _hwnd;
BYTE _forest[MAX_SIDE][MAX_SIDE], _forestT[MAX_SIDE][MAX_SIDE];
float _p, _f;
};
//--------------------------------------------------------------------------------------------------
class wnd
{
public:
int wnd::Run( HINSTANCE hInst )
{
_hInst = hInst;
_hwnd = InitAll();
_ff.setHWND( _hwnd );
_ff.initForest( 0.02f, 0.001f );
ShowWindow( _hwnd, SW_SHOW );
UpdateWindow( _hwnd );
MSG msg;
ZeroMemory( &msg, sizeof( msg ) );
while( msg.message != WM_QUIT )
{
if( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ) != 0 )
{
TranslateMessage( &msg );
DispatchMessage( &msg );
}
else
{
_ff.mainLoop();
}
}
return UnregisterClass( "_FOREST_FIRE_", _hInst );
}
private:
static int WINAPI wnd::WndProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
switch( msg )
{
case WM_DESTROY: PostQuitMessage( 0 ); break;
default:
return DefWindowProc( hWnd, msg, wParam, lParam );
}
return 0;
}
HWND InitAll()
{
WNDCLASSEX wcex;
ZeroMemory( &wcex, sizeof( wcex ) );
wcex.cbSize = sizeof( WNDCLASSEX );
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = ( WNDPROC )WndProc;
wcex.hInstance = _hInst;
wcex.hCursor = LoadCursor( NULL, IDC_ARROW );
wcex.hbrBackground = ( HBRUSH )( COLOR_WINDOW + 1 );
wcex.lpszClassName = "_FOREST_FIRE_";
RegisterClassEx( &wcex );
return CreateWindow( "_FOREST_FIRE_", ".: Forest Fire -- PJorente :.", WS_SYSMENU, CW_USEDEFAULT, 0, MAX_SIDE, MAX_SIDE, NULL, NULL, _hInst, NULL );
}
HINSTANCE _hInst;
HWND _hwnd;
forest _ff;
};
//--------------------------------------------------------------------------------------------------
int APIENTRY _tWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow )
{
srand( GetTickCount() );
wnd myWnd;
return myWnd.Run( hInstance );
}
//--------------------------------------------------------------------------------------------------
Ceylon
import ceylon.random { DefaultRandom }
abstract class Cell() of tree | dirt | burning {}
object tree extends Cell() { string => "A"; }
object dirt extends Cell() { string => " "; }
object burning extends Cell() { string => "#"; }
class Forest(Integer width, Integer height, Float f, Float p) {
value random = DefaultRandom();
function chance(Float probability) => random.nextFloat() < probability;
value sparked => chance(f);
value sprouted => chance(p);
alias Point => Integer[2];
interface Row => {Cell*};
object doubleBufferedGrid satisfies
Correspondence<Point, Cell> &
KeyedCorrespondenceMutator<Point, Cell> {
value grids = [
Array {
for (j in 0:height)
Array {
for (i in 0:width)
chance(0.5) then tree else dirt
}
},
Array {
for (j in 0:height)
Array.ofSize(width, dirt)
}
];
variable value showFirst = true;
value currentState => showFirst then grids.first else grids.last;
value nextState => showFirst then grids.last else grids.first;
shared void swapStates() => showFirst = !showFirst;
shared {Row*} rows => currentState;
shared actual Boolean defines(Point key) =>
let (x = key[0], y = key[1])
0 <= x < width && 0 <= y < height;
shared actual Cell? get(Point key) =>
let (x = key[0], y = key[1])
currentState.get(y)?.get(x);
shared actual void put(Point key, Cell cell) {
value [x, y] = key;
nextState.get(y)?.set(x, cell);
}
}
variable value evolutions = 0;
shared Integer generation => evolutions + 1;
shared void evolve() {
evolutions++;
function firesNearby(Integer x, Integer y) => {
for (j in y - 1 : 3)
for (i in x - 1 : 3)
doubleBufferedGrid[[i, j]]
}.coalesced.any(burning.equals);
for(j->row in doubleBufferedGrid.rows.indexed) {
for(i->cell in row.indexed) {
switch (cell)
case (burning) {
doubleBufferedGrid[[i, j]] = dirt;
}
case (dirt) {
doubleBufferedGrid[[i, j]] = sprouted then tree else dirt;
}
case (tree) {
doubleBufferedGrid[[i, j]] =
firesNearby(i, j) || sparked
then burning else tree;
}
}
}
doubleBufferedGrid.swapStates();
}
shared void display() {
void drawLine() => print("-".repeat(width + 2));
drawLine();
for (row in doubleBufferedGrid.rows) {
process.write("|");
for (cell in row) {
process.write(cell.string);
}
print("|");
}
drawLine();
}
}
shared void run() {
value forest = Forest(78, 38, 0.02, 0.03);
while (true) {
forest.display();
print("Generation ``forest.generation``");
print("Press enter for next generation or q and then enter to quit");
value input = process.readLine();
if (exists input, input.trimmed.lowercased == "q") {
return;
}
forest.evolve();
}
}
Clojure
(def burn-prob 0.1)
(def new-tree-prob 0.5)
(defn grow-new-tree? [] (> new-tree-prob (rand)))
(defn burn-tree? [] (> burn-prob (rand)))
(defn tree-maker [] (if (grow-new-tree?) :tree :grass))
(defn make-forest
([] (make-forest 5))
([size]
(take size (repeatedly #(take size (repeatedly tree-maker))))))
(defn tree-at [forest row col] (try (-> forest
(nth row)
(nth col))
(catch Exception _ false)))
(defn neighbores-burning? [forest row col]
(letfn [(burnt? [row col] (= :burnt (tree-at forest row col)))]
(or
(burnt? (inc row) col)
(burnt? (dec row) col)
(burnt? row (inc col))
(burnt? row (dec col)))))
(defn lightning-strike [forest]
(map (fn [forest-row]
(map #(if (and (= % :tree) (burn-tree?))
:fire!
%)
forest-row)
)
forest))
(defn burn-out-trees [forest]
(map (fn [forest-row]
(map #(case %
:burnt :grass
:fire! :burnt
%)
forest-row))
forest))
(defn burn-neighbores [forest]
(let [forest-size (count forest)
indicies (partition forest-size (for [row (range forest-size) col (range forest-size)] (cons row (list col))))]
(map (fn [forest-row indicies-row]
(map #(if (and
(= :tree %)
(neighbores-burning? forest (first %2) (second %2)))
:fire!
%)
forest-row indicies-row))
forest indicies)))
(defn grow-new-trees [forest] (map (fn [forest-row]
(map #(if (= % :grass)
(tree-maker)
%)
forest-row))
forest))
(defn forest-fire
([] (forest-fire 5))
([forest-size]
(loop
[forest (make-forest forest-size)]
(pprint forest)
(Thread/sleep 300)
(-> forest
(burn-out-trees)
(lightning-strike)
(burn-neighbores)
(grow-new-trees)
(recur)))))
(forest-fire)
example output
((:tree :tree :grass :tree :tree) (:tree :grass :tree :tree :tree) (:fire! :tree :tree :grass :tree) (:fire! :fire! :tree :tree :tree) (:burnt :tree :tree :fire! :grass)) ((:tree :tree :grass :tree :tree) (:fire! :tree :tree :fire! :tree) (:burnt :fire! :tree :grass :tree) (:burnt :burnt :fire! :fire! :tree) (:grass :fire! :fire! :burnt :tree))
COBOL
IDENTIFICATION DIVISION.
PROGRAM-ID. forest-fire.
DATA DIVISION.
WORKING-STORAGE SECTION.
*> Probability represents a fraction of 10000.
*> For instance, IGNITE-PROB means a tree has a 1 in 10000 chance
*> of igniting.
78 IGNITE-PROB VALUE 1.
78 NEW-TREE-PROB VALUE 100.
78 EMPTY-PROB VALUE 3333.
78 AREA-SIZE VALUE 40.
01 sim-table.
03 sim-row OCCURS AREA-SIZE TIMES INDEXED BY row-index.
05 sim-area OCCURS AREA-SIZE TIMES
INDEXED BY col-index.
07 current-status PIC 9.
*> The flags correspond to the colours they will
*> be displayed as.
88 empty VALUE 0. *> Black
88 tree VALUE 2. *> Green
88 burning VALUE 4. *> Red
07 next-status PIC 9.
88 empty VALUE 0.
88 tree VALUE 2.
88 burning VALUE 4.
01 rand-num PIC 9999.
01 next-row PIC 9(4).
01 next-col PIC 9(4).
01 neighbours-row PIC 9(4).
01 neighbours-col PIC 9(4).
PROCEDURE DIVISION.
main-line.
*> Seed RANDOM with current time.
MOVE FUNCTION RANDOM(FUNCTION CURRENT-DATE (9:8)) TO rand-num
PERFORM initialise-table
PERFORM FOREVER
PERFORM show-simulation
PERFORM step-simulation
END-PERFORM
GOBACK
.
initialise-table.
PERFORM VARYING row-index FROM 1 BY 1
UNTIL AREA-SIZE < row-index
AFTER col-index FROM 1 BY 1
UNTIL AREA-SIZE < col-index
PERFORM get-rand-num
IF rand-num <= EMPTY-PROB
SET empty OF current-status (row-index, col-index)
TO TRUE
SET empty OF next-status (row-index, col-index)
TO TRUE
ELSE
SET tree OF current-status (row-index, col-index)
TO TRUE
SET tree OF next-status (row-index, col-index)
TO TRUE
END-IF
END-PERFORM
.
show-simulation.
PERFORM VARYING row-index FROM 1 BY 1
UNTIL AREA-SIZE < row-index
AFTER col-index FROM 1 BY 1
UNTIL AREA-SIZE < col-index
DISPLAY SPACE AT LINE row-index COLUMN col-index
WITH BACKGROUND-COLOR
current-status (row-index, col-index)
END-PERFORM
.
*> Updates the simulation.
step-simulation.
PERFORM VARYING row-index FROM 1 BY 1
UNTIL AREA-SIZE < row-index
AFTER col-index FROM 1 BY 1
UNTIL AREA-SIZE < col-index
EVALUATE TRUE
WHEN empty OF current-status (row-index, col-index)
PERFORM get-rand-num
IF rand-num <= NEW-TREE-PROB
SET tree OF next-status
(row-index, col-index) TO TRUE
END-IF
WHEN tree OF current-status (row-index, col-index)
PERFORM simulate-tree
WHEN burning OF current-status
(row-index, col-index)
SET empty OF next-status (row-index, col-index)
TO TRUE
END-EVALUATE
END-PERFORM
PERFORM update-statuses.
.
*> Updates a tree tile, assuming row-index and col-index are at
*> a tree area.
simulate-tree.
*> Find the row and column of the bottom-right neighbour.
COMPUTE next-row = FUNCTION MIN(row-index + 1, AREA-SIZE)
COMPUTE next-col = FUNCTION MIN(col-index + 1, AREA-SIZE)
COMPUTE neighbours-row = FUNCTION MAX(row-index - 1, 1)
COMPUTE neighbours-col = FUNCTION MAX(col-index - 1, 1)
*> If a neighbour is burning, catch fire.
PERFORM VARYING neighbours-row FROM neighbours-row BY 1
UNTIL next-row < neighbours-row
*> Check if neighbours in a row are on fire.
PERFORM VARYING neighbours-col FROM neighbours-col BY 1
UNTIL next-col < neighbours-col
IF neighbours-row = row-index
AND neighbours-col = col-index
EXIT PERFORM CYCLE
END-IF
IF burning OF current-status
(neighbours-row, neighbours-col)
SET burning OF next-status (row-index, col-index)
TO TRUE
EXIT PARAGRAPH
END-IF
END-PERFORM
*> Move neighbours-col back to starting position
COMPUTE neighbours-col =
FUNCTION MAX(neighbours-col - 3, 1)
END-PERFORM
*> Otherwise, there is a random chance of
*> catching fire.
PERFORM get-rand-num
IF rand-num <= IGNITE-PROB
SET burning OF next-status (row-index, col-index) TO TRUE
END-IF
.
update-statuses.
PERFORM VARYING row-index FROM 1 BY 1
UNTIL AREA-SIZE < row-index
AFTER col-index FROM 1 BY 1
UNTIL AREA-SIZE < col-index
MOVE next-status (row-index, col-index)
TO current-status (row-index, col-index)
END-PERFORM
.
*> Puts a random value between 0 and 9999 in rand-num.
get-rand-num.
COMPUTE rand-num =
FUNCTION MOD(FUNCTION RANDOM * 100000, 10000)
.
Common Lisp
(defvar *dims* '(10 10))
(defvar *prob-t* 0.5)
(defvar *prob-f* 0.1)
(defvar *prob-p* 0.01)
(defmacro with-gensyms (names &body body)
`(let ,(mapcar (lambda (n) (list n '(gensym))) names)
,@body))
(defmacro traverse-grid (grid rowvar colvar (&rest after-cols) &body body)
(with-gensyms (dims rows cols)
`(let* ((,dims (array-dimensions ,grid))
(,rows (car ,dims))
(,cols (cadr ,dims)))
(dotimes (,rowvar ,rows ,grid)
(dotimes (,colvar ,cols ,after-cols)
,@body)))))
(defun make-new-forest (&optional (dims *dims*))
(let ((forest (make-array dims :element-type 'symbol :initial-element 'void)))
(traverse-grid forest row col nil
(if (<= (random 1.0) *prob-t*)
(setf (aref forest row col) 'tree)))))
(defun print-forest (forest)
(traverse-grid forest row col (terpri)
(ecase (aref forest row col)
((void) (write-char #\space))
((tree) (write-char #\T))
((fire) (write-char #\#))))
(values))
(defvar *neighboring* '((-1 . -1) (-1 . 0) (-1 . 1)
(0 . -1) (0 . 1)
(1 . -1) (1 . 0) (1 . 1)))
(defun neighbors (forest row col)
(loop for n in *neighboring*
for nrow = (+ row (car n))
for ncol = (+ col (cdr n))
when (array-in-bounds-p forest nrow ncol)
collect (aref forest nrow ncol)))
(defun evolve-tree (forest row col)
(let ((tree (aref forest row col)))
(cond ((eq tree 'fire) ;; if the tree was on fire, it's dead Jim
'void)
((and (eq tree 'tree) ;; if a neighbor is on fire, it's on fire too
(find 'fire (neighbors forest row col) :test #'eq))
'fire)
((and (eq tree 'tree) ;; random chance of fire happening
(<= (random 1.0) *prob-f*))
'fire)
((and (eq tree 'void) ;; random chance of empty space becoming a tree
(<= (random 1.0) *prob-p*))
'tree)
(t tree))))
(defun evolve-forest (forest)
(let* ((dims (array-dimensions forest))
(new (make-array dims :element-type 'symbol :initial-element 'void)))
(traverse-grid forest row col nil
(setf (aref new row col) (evolve-tree forest row col)))
new))
(defun simulate (forest n &optional (print-all t))
(format t "------ Initial forest ------~%")
(print-forest forest)
(dotimes (i n)
(setf forest (evolve-forest forest))
(when print-all
(progn (format t "~%------ Generation ~d ------~%" (1+ i))
(print-forest forest)))))
Example results:
CL-USER>(defparameter *forest* (make-new-forest))
CL-USER>(simulate *forest* 5)
------ Initial forest ------
TTTTT TT
TTT TT
TT T T
TTTT T TT
T TT T T
T TTT
TTTT TTT
T
T T T T
TTT TTT T
------ Generation 1 ------
TTTTT TT
TTT TT
TT T T
TTTT T TT
T TT T T
T TTT
TTTT TTT
T
T T T T
TTT TTT T
------ Generation 2 ------
TTTTT TT
TTT TT
TT T T
TTTT T TT
TTTT T T
T TTT
TTT# TTT
T
T T T T
TTT TTT T
------ Generation 3 ------
TTTTT TT
TTT TT
TT T T
TTTT T TT
TTTT T T
# TTT
TT# TTT
T
T T T T
TTT TTT T
------ Generation 4 ------
TTTTT TT
TTT TT
TT T TT
TTTT T TT
TTT# T T
TTT
T# TTT
T
T T T T
TTT TTT T
------ Generation 5 ------
TTTTT TT
TTT TT
TT T TT
T### T TT
TT# T T
TTT
# TTT
T
T T T T
TTT TTT T
NIL
D
Textual Version
import std.stdio, std.random, std.string, std.algorithm;
enum treeProb = 0.55; // Original tree probability.
enum fProb = 0.01; // Auto combustion probability.
enum cProb = 0.01; // Tree creation probability.
enum Cell : char { empty=' ', tree='T', fire='#' }
alias World = Cell[][];
bool hasBurningNeighbours(in World world, in ulong r, in ulong c)
pure nothrow @safe @nogc {
foreach (immutable rowShift; -1 .. 2)
foreach (immutable colShift; -1 .. 2)
if ((r + rowShift) >= 0 && (r + rowShift) < world.length &&
(c + colShift) >= 0 && (c + colShift) < world[0].length &&
world[r + rowShift][c + colShift] == Cell.fire)
return true;
return false;
}
void nextState(in World world, World nextWorld) /*nothrow*/ @safe /*@nogc*/ {
foreach (r, row; world)
foreach (c, elem; row)
final switch (elem) with (Cell) {
case empty:
nextWorld[r][c]= (uniform01 < cProb) ? tree : empty;
break;
case tree:
if (world.hasBurningNeighbours(r, c))
nextWorld[r][c] = fire;
else
nextWorld[r][c] = (uniform01 < fProb) ? fire : tree;
break;
case fire:
nextWorld[r][c] = empty;
break;
}
}
void main() @safe {
auto world = new World(8, 65);
foreach (row; world)
foreach (ref el; row)
el = (uniform01 < treeProb) ? Cell.tree : Cell.empty;
auto nextWorld = new World(world.length, world[0].length);
foreach (immutable i; 0 .. 4) {
nextState(world, nextWorld);
writefln("%(%(%c%)\n%)\n", nextWorld);
world.swap(nextWorld);
}
}
- Output:
T T T#TT T TT TT TTTT TT TTT T TT T# T T TT TT TTTTT T TT TT T TTTTTTTTTT T TTT T T T TT TTTTTTTT TTTT #T TT T TTTTTT TTTTT TTT TTTT TTTT TTT T T T T T TT T TT T TT T TT T TT T TTTT T T TT TTT T TT T T T TT T TTT T TTTT T# T T T TTT TT TTTTT T T TT T T TT T TT TTTT TTT TTTTT T T T T TT T TTT T T T TT TTT T T T TTT T TT T TTT#TT T TT TTTTTTTT TTTT TTTTT TTTT TTT TT TTTTT TTTTTT TT TT T TT T TT T TT T TT TT TTTT TTTTT T T # #T T TT TT TTTT TT TTT T TT # T T TT TT TT### T TT TT # TTTTTTTTTT T TTT T T T ## TTTTTTTT TTTT # TT T TTTTTT TTTTT TTT TTTT TTTT TTT # T T T T TT T T# T TT T TT T TT T #TTT T T TT TTT T TT T T T TTT T TTT T TTTT # T T T TTT TT TTTTT T T TT T T TT T TT TTTT TTT T#### # T T T TT T TTT T T T TT TTT T T T TTT T TT T TT# #T T TT TTTTTTTT TTTT TTTTT TTTT TTT TT TTTTT TTTTTT TT ## T TT T TT T TT T TT TT TTTT TTTTT T T # T TT TT TTTT TT TTT T TT T T TT TT T# T TT TT TTTTTTTTTT T TTT T T T TTTTTTTT TTT# TT T T###TT TTT## TTT TTTT TTTT TT# T T T T #T T # T TT T TT T TT # #TT T T TT TTT T T# T T T TTT # TTT T TTTT # # T TTT TT TTTTT T T TT T T TT T TT TTTT TTT # T T # TT T TTT T T T TT TTT T T T TTT T TT # ## # T TT TTTTTTTT TTTT TTTTT TTTT TTT TT TTTTT TT#TTT TT T TT T TT T TT T TT TT TTTT TTTTT T T T TT TT TTTT TT TTT T TT T T TT TT # T TT T# TT####TTTT T TTT T T T TTTTTT## TT# TT T # #T ### TTT TTTT TTTT T# T T T T # T T TT T ## # TT ## T T TT TTT T # T T # #TT TTT T TTTT T ### TT TTTTT # T TT T T T# # TT TTTT TTT # T TT T TTT T T T TT TTT T T T TTT T ## T ## TTTTTTTT TTTT TTTTT TTTT TTT TT TTTTT T# #T# ## # TT T TT T TT T TT TT TTTT TTTTT
Graphical Version
import std.stdio, std.random, std.algorithm, std.typetuple,
simpledisplay;
enum double TREE_PROB = 0.55; // Original tree probability.
enum double F_PROB = 0.01; // Auto combustion probability.
enum double P_PROB = 0.01; // Tree creation probability.
enum worldSide = 600;
enum Cell : ubyte { empty, tree, burning }
alias World = Cell[worldSide][];
immutable white = Color(255, 255, 255),
red = Color(255, 0, 0),
green = Color(0, 255, 0);
void nextState(ref World world, ref World nextWorld,
ref Xorshift rnd, Image img) {
immutable nr = world.length;
immutable nc = world[0].length;
foreach (immutable r, const row; world)
foreach (immutable c, immutable elem; row)
START: final switch (elem) with (Cell) {
case empty:
img.putPixel(c, r, white);
nextWorld[r][c] = rnd.uniform01 < P_PROB ? tree : empty;
break;
case tree:
img.putPixel(c, r, green);
foreach (immutable rowShift; TypeTuple!(-1, 0, 1))
foreach (immutable colShift; TypeTuple!(-1, 0, 1))
if ((r + rowShift) >= 0 && (r + rowShift) < nr &&
(c + colShift) >= 0 && (c + colShift) < nc &&
world[r + rowShift][c + colShift] == Cell.burning) {
nextWorld[r][c] = Cell.burning;
break START;
}
nextWorld[r][c]= rnd.uniform01 < F_PROB ? burning : tree;
break;
case burning:
img.putPixel(c, r, red);
nextWorld[r][c] = empty;
break;
}
swap(world, nextWorld);
}
void main() {
auto rnd = Xorshift(1);
auto world = new World(worldSide);
foreach (ref row; world)
foreach (ref el; row)
el = rnd.uniform01 < TREE_PROB ? Cell.tree : Cell.empty;
auto nextWorld = new World(world[0].length);
auto w= new SimpleWindow(world.length,world[0].length,"ForestFire");
auto img = new Image(w.width, w.height);
w.eventLoop(1, {
auto painter = w.draw;
nextState(world, nextWorld, rnd, img);
painter.drawImage(Point(0, 0), img);
});
}
Déjà Vu
#chance of empty->tree
set :p 0.004
#chance of spontaneous tree combustion
set :f 0.001
#chance of tree in initial state
set :s 0.5
#height of world
set :H 10
#width of world
set :W 20
has-burning-neigbour state pos:
for i range -- swap ++ dup &< pos:
for j range -- swap ++ dup &> pos:
& i j
try:
state!
catch value-error:
:empty
if = :burning:
return true
false
evolve state pos:
state! pos
if = :tree dup:
if has-burning-neigbour state pos:
:burning drop
elseif chance f:
:burning drop
elseif = :burning:
:empty
else:
if chance p:
:tree
else:
:empty
step state:
local :next {}
for k in keys state:
set-to next k evolve state k
next
local :(c) { :tree "T" :burning "B" :empty "." }
print-state state:
for j range 0 H:
for i range 0 W:
!print\ (c)! state! & i j
!print ""
init-state:
local :first {}
for j range 0 H:
for i range 0 W:
if chance s:
:tree
else:
:empty
set-to first & i j
first
run:
init-state
while true:
print-state dup
!print ""
step
run-slowly:
init-state
while true:
print-state dup
drop !prompt "Continue."
step
run- Output:
T.T.T...T..T..TT.T.T. .TT.T...T..T....TTTTT ......T.TTT.TTTTT.... ..TTT...T.T..T..TTT.. ....T.....TTT...TTTTT ..TTT..TTTTTTTTT....T T....T..TT.TT.T...T.. TTT.TT.T..TT.TTT.TT.. .TT.TT.T...T.T..T.TTT ..TTTTT...TTTTTT..T.T TT..T....T..T..TTTT.. TTT.T...T..T.TTT.T.T. .TT.T...T..T..T.TTTTT ......T.TTT.TTTTT.... ..TTT...T.T..T..TTT.. ....TT....TTB...TTTTT ..TTT..TTTTTTTTT...TT T....T.TTT.TT.T...T.. TTT.TT.T..TB.TTT.TT.. .TT.TT.T...T.T..T.TTT ..TTTTB...TTTTTT..T.T TT..T....T..T..TTTT.. TTT.T...T..T.TTT.T.T. .TTTT...T..T..T.TTTTT ......T.TTTTTTTTT.... ..TTT...T.T..B..TTT.. ....TT....TB....TTTTT ..TTT..TTTTBBBTT...TT T....T.TTT.BB.T...T.. TTT.TT.T..B..TTT.TT.. .TTTTB.B...B.T..T.TTT ..TTTB....TTTTTT..T.T TT..T....T..T..TTTT..
EasyLang
p_fire = 0.00002
p_tree = 0.002
#
len f[] 102 * 102
len p[] len f[]
background 100
clear
for r = 0 to 99
for c = 0 to 99
i = r * 102 + c + 104
if randomf < 0.5
f[i] = 1
.
.
.
timer 0
#
subr show
for r = 0 to 99
for c = 0 to 99
i = r * 102 + c + 104
h = f[i]
if h <> p[i]
move c + 0.5 r + 0.5
if h = 0
color 100
circle 0.6
elif h = 1
color 151
circle 0.5
else
color 9 * 100 + (18 - 2 * h) * 10
circle 0.5
.
.
.
.
.
subr update
swap f[] p[]
for r = 0 to 99
for c = 0 to 99
i = r * 102 + c + 104
if p[i] = 0
f[i] = 0
if randomf < p_tree
f[i] = 1
.
elif p[i] = 1
f[i] = 1
s = p[i - 103] + p[i - 102] + p[i - 101]
s += p[i - 1] + p[i + 1]
s += p[i + 101] + p[i + 102] + p[i + 103]
if s >= 9 or randomf < p_fire
f[i] = 9
.
elif p[i] = 4
f[i] = 0
else
f[i] = p[i] - 1
.
.
.
.
on timer
show
update
timer 0.2
.
Emacs Lisp
#!/usr/bin/env emacs -script
;; -*- lexical-binding: t -*-
;; run: ./forest-fire forest-fire.config
(require 'cl-lib)
;; (setq debug-on-error t)
(defmacro swap (a b)
`(setq ,b (prog1 ,a (setq ,a ,b))))
(defconst burning ?B)
(defconst tree ?t)
(cl-defstruct world rows cols data)
(defun new-world (rows cols)
;; When allocating the vector add padding so the border will always be empty.
(make-world :rows rows :cols cols :data (make-vector (* (1+ rows) (1+ cols)) nil)))
(defmacro world--rows (w)
`(1+ (world-rows ,w)))
(defmacro world--cols (w)
`(1+ (world-cols ,w)))
(defmacro world-pt (w r c)
`(+ (* (mod ,r (world--rows ,w)) (world--cols ,w))
(mod ,c (world--cols ,w))))
(defmacro world-ref (w r c)
`(aref (world-data ,w) (world-pt ,w ,r ,c)))
(defun print-world (world)
(dotimes (r (world-rows world))
(dotimes (c (world-cols world))
(let ((cell (world-ref world r c)))
(princ (format "%c" (if (not (null cell))
cell
?.)))))
(terpri)))
(defun random-probability ()
(/ (float (random 1000000)) 1000000))
(defun initialize-world (world p)
(dotimes (r (world-rows world))
(dotimes (c (world-cols world))
(setf (world-ref world r c) (if (<= (random-probability) p) tree nil)))))
(defun neighbors-burning (world row col)
(let ((n 0))
(dolist (offset '((1 . 1) (1 . 0) (1 . -1) (0 . 1) (0 . -1) (-1 . 1) (-1 . 0) (-1 . -1)))
(when (eq (world-ref world (+ row (car offset)) (+ col (cdr offset))) burning)
(setq n (1+ n))))
(> n 0)))
(defun advance (old new p f)
(dotimes (r (world-rows old))
(dotimes (c (world-cols old))
(cond
((eq (world-ref old r c) burning)
(setf (world-ref new r c) nil))
((null (world-ref old r c))
(setf (world-ref new r c) (if (<= (random-probability) p) tree nil)))
((eq (world-ref old r c) tree)
(setf (world-ref new r c) (if (or (neighbors-burning old r c)
(<= (random-probability) f))
burning
tree)))))))
(defun read-config (file-name)
(with-temp-buffer
(insert-file-contents-literally file-name)
(read (current-buffer))))
(defun get-config (key config)
(let ((val (assoc key config)))
(if (null val)
(error (format "missing value for %s" key))
(cdr val))))
(defun simulate-forest (file-name)
(let* ((config (read-config file-name))
(rows (get-config 'rows config))
(cols (get-config 'cols config))
(skip (get-config 'skip config))
(a (new-world rows cols))
(b (new-world rows cols)))
(initialize-world a (get-config 'tree config))
(dotimes (time (get-config 'time config))
(when (or (and (> skip 0) (= (mod time skip) 0))
(<= skip 0))
(princ (format "* time %d\n" time))
(print-world a))
(advance a b (get-config 'p config) (get-config 'f config))
(swap a b))))
(simulate-forest (elt command-line-args-left 0))
The configuration file controls the simulation.
((rows . 10)
(cols . 45)
(time . 100)
(skip . 10)
(f . 0.001) ;; probability tree ignites
(p . 0.01) ;; probability empty space fills with a tree
(tree . 0.5)) ;; initial probability of tree in a new world
- Output:
* time 0 .t...t..t.t.t...ttt...tttt..tt...t.t.t.t.t..t .t.t.t..t.ttt.tt.tttt.tt....t.t.tt.t.t.tt.ttt t..t.tttt..t..tt..tt.t.t.tt.....t..t..tt.tt.t .tt.t.ttt.t...t...tt..t....tttttt.t..tt.tt.tt .t..t..t.tt.t...tt...t.t.tt.t.t..ttttt.t..ttt .tt.ttttt..t.t....tttt.t.t..tttttt.tt.t.t.t.t ttt.....t.tttttttt.tt....ttt.t.....t.ttt..ttt .tt..tt.tt.ttt...tt.t..ttt.t.tt.tt....tttt... t.tt...tttt...t.t.tt.tt..ttt...t.tt.t.tttttt. ...t......t.t...tttt...ttttt.tttt..t..t.tttt. * time 10 ......................tttt..tt...t.B........B ....................B.tt...tt.t.tt..........B .....................t.t.tt.....B...........B ...........t..........t...tttttB............B .............t..tB...t.t.tt.t.tB.........t..B .........t.......ttttt.t.tt.tttB............. ................Btttt....ttttt...........t... t....B...t.......tt.t..ttt.t.tt.BB........... .....B..........t.ttttt..ttt..tt.tt.t...t.... ................tttt...ttttt.tttt..t......... * time 20 ..........t.....t.t................t........t .....t...........t.t......................... .........................t..............t.... ..........tttt..........................t.... .t.........t.t...........................t... ....t....t......................t............ ..t.tt.....t..............t........t.t...t... tt.......t................................... ..t...t.........................t....t..t.t.. .....t....................................... * time 30 ......t...t.....t.t......t.........t.......tt .....t.........t.t.t...............t...t..... ...........tt.........t..t..t......t....t.... ..........tttt.......t.....t.........t..t.... .t.........t.t...t.tt..........t.........t... ....t....t......t.tt.t..........t.......t.... ..t.tt.....t..t.....t.t...t..tB....t.t...t... tt..t....t.......t..................t........ ..t...t....t...........t........t....t..t.t.. .....t...t....t..t....tt.t.....t...........t. * time 40 ......t...t.....t.t......t......t..t.......tt .....t.........t.t.tt..............tt..t..... ...........tt............t..t......t....tt... t...t.....tttt.............tt.t.t....t..t.... .t.........t.t......t..........t.........t... ....t....t...t........t.t.......t.t..t..t.... ..t.tt.....t..B....t......t....t...t.t...t... tt..t....t.t.....tt.................t........ ..t...t....t..t........tt.t.....t....t..t.t.. ..t..t...t....t..t....tt.t.....t......t....t. * time 50 ......t...t.....t.t......t.....tt.t...t....tt ..t.tt.........t.t.tt.t......t.t...t...t..... .........................t..t..t..t.....tt... t...t......................tt.t.t....t..t...t .t..................t.........tt.........t..t ....t....t..........t.t.t.......t.t..t..t.... ..tttt...t.t.......t......t....t...ttt...tt.t tt..t.t..t.t.....tt.................t........ ..t...t....t..t....t...tt.t.....t....tt.t.t.. ..t..t...t....t..t....tt.t.t...t....t.t....t. * time 60 ......t...t.t...t.t.t....t.....tt.t...t....tt ..t.tt.......t.t.t.tt.t......t.t...t...t..t.t ......t.t...............tt.tt..t..t.....tt... t...t.t.............t......tt.t.t....t..t...t tt...............tttt.........tt.........t..t ....tt.ttt..t.......t.t.t.t.....t.t..t..t.... ..tttt...ttt.......t......t....t...ttt..ttt.t tt..t.t.tt.t...t.tt.................t....t... ..tt..t....t..t..t.t...B........t....tt.t.t.. ..t..t...t....t..t..t.tB...Bt..t...tt.t....t. * time 70 ......tt..t.t...t.t.t.t..t.....tt.t...t....tt t.t.tt.......t.t.t.tt.t.....tttt...t...t..t.t .t....t.t............t..tt.tt..t..t....ttt... t...t.tt..t.....t...t...t..tt.t.tt...t..t.t.t tt.....t.........tttt.........tt..t......tt.t ....ttttttt.t...t...t.t.t.t.....t.t..t..t.t.. ..tttt...ttt..t....t......t...tt...ttt..ttt.t ttt.t.t.tttt...t.tt....t.......t....tt..tt... ..tt..ttt.tt..t..ttt.....t......t...ttt.t.t.. ..t..tt..t....t.tt..t..........t.t.tt.t...tt. * time 80 ....t.tt.tt.t...t.t.t.t..t....ttt.t.........B t.t.tt.......t.t.t.tt.t.....ttttt..t........B .t....t.t............t..tt.tt..t..t.......... t...t.ttt.t.....t...t...t..tt.tttt...t......t tt.....t.......tttttt....t....ttt.ttt.......t ....ttttttt.t..tt..tt.t.t.t.....t.t..t....... ..tttt...ttt..tt...t......t...tt...ttt......t ttt.t.t.tttt...t.tt....t......ttt...tt..BB... ..ttt.ttt.tt..t..tttt....tt.....t...ttt.t.t.. ..t..tt..t....tttt.tt..........t.t.tt.t...tt. * time 90 ....t.tt.tt.t...t.t.t.t..t........B.......... t.t.tt.......t.ttt.tt.t.............B........ tt....t.t.t.......t..t..tt................... t...t.ttt.t.....t.t.t.t.t............t..t...t tt.tt.tt.......tttttt....t..........B...t...t ....ttttttt.t..ttt.tt.ttt.t..........t.....t. ..tttt...ttt..tt.t.t......t........Btt..t.t.t ttt.t.t.tttt...t.tt..t.t...........ttt....... ..ttt.ttt.tt..t..tttt.t..tt.....BB..ttt...... ..t..tt..t....tttt.tt.......t..t.t.tt.t......
Erlang
Not even text graphics. Notice the use of random:seed/1 when creating a tree. Without it all calls to random:uniform/1 gave the same result for each tree.
-module( forest_fire ).
-export( [task/0] ).
-record( state, {neighbours=[], position, probability_burn, probability_grow, tree} ).
task() ->
erlang:spawn( fun() ->
Pid_positions = forest_create( 5, 5, 0.5, 0.3, 0.2 ),
Pids = [X || {X, _} <- Pid_positions],
[X ! {tree_pid_positions, Pid_positions} || X <- Pids],
Start = forest_status( Pids ),
Histories = [Start | [forest_step( Pids ) || _X <- lists:seq(1, 2)]],
[io:fwrite("~p~n~n", [X]) || X <- Histories]
end ).
forest_create( X_max, Y_max, Init, Grow, Burn ) ->
[{tree_create(tree_init(Init, random:uniform()), X, Y, Grow, Burn), {X,Y}} || X <- lists:seq(1, X_max), Y<- lists:seq(1, Y_ma\
x)].
forest_status( Pids ) ->
[X ! {status_request, erlang:self()} || X <- Pids],
[receive {status, Tree, Position, X} -> {Tree, Position} end || X <- Pids].
forest_step( Pids ) ->
[X ! {step} || X <- Pids],
forest_status( Pids ).
is_neighbour({X, Y}, {X, Y} ) -> false; % Myself
is_neighbour({Xn, Yn}, {X, Y} ) when abs(Xn - X) =< 1, abs(Yn - Y) =< 1 -> true;
is_neighbour( _Position_neighbour, _Position ) -> false.
loop( State ) ->
receive
{tree_pid_positions, Pid_positions} ->
loop( loop_neighbour(Pid_positions, State) );
{step} ->
[X ! {tree, State#state.tree, erlang:self()} || X <- State#state.neighbours],
loop( loop_step(State) );
{status_request, Pid} ->
Pid ! {status, State#state.tree, State#state.position, erlang:self()},
loop( State )
end.
loop_neighbour( Pid_positions, State ) ->
My_position = State#state.position,
State#state{neighbours=[Pid || {Pid, Position} <- Pid_positions, is_neighbour( Position, My_position)]}.
loop_step( State ) ->
Is_burning = lists:any( fun loop_step_burning/1, [loop_step_receive(X) || X <- State#state.neighbours] ),
Tree = loop_step_next( Is_burning, random:uniform(), State ),
State#state{tree=Tree}.
loop_step_burning( Tree ) -> Tree =:= burning.
loop_step_next( _Is_burning, Probablility, #state{tree=empty, probability_grow=Grow} ) when Grow > Probablility -> tree;
loop_step_next( _Is_burning, _Probablility, #state{tree=empty} ) -> empty;
loop_step_next( _Is_burning, _Probablility, #state{tree=burning} ) -> empty;
loop_step_next( true, _Probablility, #state{tree=tree} ) -> burning;
loop_step_next( false, Probablility, #state{tree=tree, probability_burn=Burn} ) when Burn > Probablility -> burning;
loop_step_next( false, _Probablility, #state{tree=tree} ) -> tree.
loop_step_receive( Pid ) -> receive {tree, Tree, Pid} -> Tree end.
tree_create( Tree, X, Y, Grow, Burn ) ->
State = #state{position={X, Y}, probability_burn=Burn, probability_grow=Grow, tree=Tree},
erlang:spawn_link( fun() -> random:seed( X, Y, 0 ), loop( State ) end ).
tree_init( Tree_probalility, Random ) when Tree_probalility > Random -> tree;
tree_init( _Tree_probalility, _Random ) -> empty.
- Output:
29> forest_fire:task().
[{tree,{1,1}},
{empty,{1,2}},
{empty,{1,3}},
{empty,{1,4}},
{tree,{1,5}},
{empty,{2,1}},
{empty,{2,2}},
{empty,{2,3}},
{tree,{2,4}},
{empty,{2,5}},
{tree,{3,1}},
{tree,{3,2}},
{empty,{3,3}},
{tree,{3,4}},
{empty,{3,5}},
{tree,{4,1}},
{tree,{4,2}},
{tree,{4,3}},
{tree,{4,4}},
{empty,{4,5}},
{tree,{5,1}},
{tree,{5,2}},
{tree,{5,3}},
{tree,{5,4}},
{empty,{5,5}}]
[{burning,{1,1}},
{tree,{1,2}},
{tree,{1,3}},
{tree,{1,4}},
{burning,{1,5}},
{tree,{2,1}},
{tree,{2,2}},
{tree,{2,3}},
{burning,{2,4}},
{tree,{2,5}},
{burning,{3,1}},
{burning,{3,2}},
{tree,{3,3}},
{burning,{3,4}},
{tree,{3,5}},
{burning,{4,1}},
{burning,{4,2}},
{burning,{4,3}},
{burning,{4,4}},
{tree,{4,5}},
{burning,{5,1}},
{burning,{5,2}},
{burning,{5,3}},
{burning,{5,4}},
{tree,{5,5}}]
[{empty,{1,1}},
{burning,{1,2}},
{burning,{1,3}},
{burning,{1,4}},
{empty,{1,5}},
{burning,{2,1}},
{burning,{2,2}},
{burning,{2,3}},
{empty,{2,4}},
{burning,{2,5}},
{empty,{3,1}},
{empty,{3,2}},
{burning,{3,3}},
{empty,{3,4}},
{burning,{3,5}},
{empty,{4,1}},
{empty,{4,2}},
{empty,{4,3}},
{empty,{4,4}},
{burning,{4,5}},
{empty,{5,1}},
{empty,{5,2}},
{empty,{5,3}},
{empty,{5,4}},
{burning,{5,5}}]
Evaldraw
Creates a 256x256 pixel forest, try adjusting the probability for ignite, spread, sprout and max neighbors.
enum{XSIZ=255, YSIZ=XSIZ} // size of forest
enum{EMPTY=0, TREE=1, BURN=2} // possible states of a cell
static prob_ignite = .000001; // very rare, but remember we have many trees.
static prob_spread = .25; // Fire spread speed/probability if neighbor on fire
static prob_sprout = 0.25; // probability of new tree to sprout
static MAX_NEIGHBORS = 6; // tree refuses to sprout if overcrowded
static forest[2][YSIZ][XSIZ]; // state of pixel
static fuel[2][YSIZ][XSIZ]; // stores fuel (wood) 0-255
static heat[2][YSIZ][XSIZ]; // tree refuses to spout if heat!=0, also, sets draw color.
static arr_numburn[YSIZ][XSIZ]; // number of burning trees for this cell
static arr_numtree[YSIZ][XSIZ]; // number of neighbor trees for this cell
static xoff[8] = {-1,+0,+1,-1,/*NA*/1,-1,+0,+1}; // offsets to find 8-connected neighbors
static yoff[8] = {-1,-1,-1,+0,/*NA*/0,+1,+1,+1};
() { // Main in evaldraw scripts is a unnamed function.
static otim;
tim = klock(); // Time since program start in seconds.
dt=tim-otim; // Deltatime. 1/dt is FPS. 0 in first frame.
otim=tim; // store old time for next dt.
simulate(); // simulate and draw are coupled, since draw also ping-pongs state.
draw();
setcol(0); fillrect(0,YSIZ,XSIZ,15);
setcol(0xffffff); moveto(0,YSIZ); printf("%4.0ffps generation %5.0f", 1 /dt, numframes);
if (bstatus>0) setFire(mousx,mousy);
}// end main
draw() {
for(y=0; y<YSIZ; y++)
for(x=0; x<XSIZ; x++)
{
cell = forest[1][y][x];
if (cell == EMPTY) setcol(0);
else if(cell==BURN) setcol(511-.25*fuel[0][y][x],255-3*heat[0][y][x],33);
else if(cell==TREE) setcol(0,64+fuel[0][y][x],0);
setpix(x,y);
// Transfer next simulation state into current ready for next frame
forest[0][y][x] = forest[1][y][x];
heat[0][y][x] = heat[1][y][x];
fuel[0][y][x] = fuel[1][y][x];
// Count neighbors burning and not
numburn = 0; numtree = 0;
for(n=0; n<8; n++) {
ypos=y+yoff[n];
xpos=x+xoff[n];
if (xpos<0 || xpos > XSIZ-1)continue;
if (ypos<0 || ypos > YSIZ-1)continue;
cell = forest[1][ypos][xpos];
if (cell==BURN) numburn++;
else if (cell==TREE) numtree++;
}
arr_numburn[y][x] = numburn;
arr_numtree[y][x] = numtree;
}
}
fillrect(x0,y0,w,h) {
x0=int(x0); y0=int(y0); w=int(w) + 1; h=int(h);
for(y=y0;y<=y0+h;y++) { moveto(x0,y); lineto(x0+w,y); }
}
simulate() {
for(y=0; y<YSIZ; y++)
for(x=0; x<XSIZ; x++) {
cell = forest[0][y][x];
cellfuel = fuel[0][y][x];
celltemp = heat[0][y][x];
rand=rnd;
numburn = arr_numburn[y][x];
numtree = arr_numtree[y][x];
if (cell == BURN) {
if (cellfuel <= 0) {
forest[1][y][x] = EMPTY;
}
else {
fuel[1][y][x] = cellfuel - 1;
heat[1][y][x] = celltemp + 1;
}
}
else if (cell == TREE) {
if (numburn == 0 && rand < prob_ignite) setFire(x,y);
else if (numburn > 0 && rand < prob_spread) setFire(x,y);
else if(cellfuel < 255) fuel[1][y][x] = cellfuel + 1;
}
else if (cell == EMPTY) {
if ( celltemp > 0 ) heat[1][y][x] = celltemp - 1;
else if (numburn==0 && rand < prob_sprout && numtree <= MAX_NEIGHBORS) setTree(x,y);
}
}
} // end sim
setFire(x,y) {
forest[1][y][x] = BURN;
}
setTree(x,y) {
forest[1][y][x] = TREE;
}
F#
This implementation can be compiled or run in the interactive F# shell.
open System
open System.Diagnostics
open System.Drawing
open System.Drawing.Imaging
open System.Runtime.InteropServices
open System.Windows.Forms
module ForestFire =
type Cell = Empty | Tree | Fire
let rnd = new System.Random()
let initial_factor = 0.35
let ignition_factor = 1e-5 // rate of lightning strikes (f)
let growth_factor = 2e-3 // rate of regrowth (p)
let width = 640 // width of the forest region
let height = 480 // height of the forest region
let make_forest =
Array2D.init height width
(fun _ _ -> if rnd.NextDouble() < initial_factor then Tree else Empty)
let count (forest:Cell[,]) row col =
let mutable n = 0
let h,w = forest.GetLength 0, forest.GetLength 1
for r in row-1 .. row+1 do
for c in col-1 .. col+1 do
if r >= 0 && r < h && c >= 0 && c < w && forest.[r,c] = Fire then
n <- n + 1
if forest.[row,col] = Fire then n-1 else n
let burn (forest:Cell[,]) r c =
match forest.[r,c] with
| Fire -> Empty
| Tree -> if rnd.NextDouble() < ignition_factor then Fire
else if (count forest r c) > 0 then Fire else Tree
| Empty -> if rnd.NextDouble() < growth_factor then Tree else Empty
// All the functions below this point are drawing the generated images to screen.
let make_image (pixels:int[]) =
let bmp = new Bitmap(width, height)
let bits = bmp.LockBits(Rectangle(0,0,width,height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)
Marshal.Copy(pixels, 0, bits.Scan0, bits.Height*bits.Width) |> ignore
bmp.UnlockBits(bits)
bmp
// This function is run asynchronously to avoid blocking the main GUI thread.
let run (box:PictureBox) (label:Label) = async {
let timer = new Stopwatch()
let forest = make_forest |> ref
let pixel = Array.create (height*width) (Color.Black.ToArgb())
let rec update gen =
timer.Start()
forest := burn !forest |> Array2D.init height width
for y in 0..height-1 do
for x in 0..width-1 do
pixel.[x+y*width] <- match (!forest).[y,x] with
| Empty -> Color.Gray.ToArgb()
| Tree -> Color.Green.ToArgb()
| Fire -> Color.Red.ToArgb()
let img = make_image pixel
box.Invoke(MethodInvoker(fun () -> box.Image <- img)) |> ignore
let msg = sprintf "generation %d @ %.1f fps" gen (1000./timer.Elapsed.TotalMilliseconds)
label.Invoke(MethodInvoker(fun () -> label.Text <- msg )) |> ignore
timer.Reset()
update (gen + 1)
update 0 }
let main args =
let form = new Form(AutoSize=true,
Size=new Size(800,600),
Text="Forest fire cellular automata")
let box = new PictureBox(Dock=DockStyle.Fill,Location=new Point(0,0),SizeMode=PictureBoxSizeMode.StretchImage)
let label = new Label(Dock=DockStyle.Bottom, Text="Ready")
form.FormClosed.Add(fun eventArgs -> Async.CancelDefaultToken()
Application.Exit())
form.Controls.Add(box)
form.Controls.Add(label)
run box label |> Async.Start
form.Show()
Application.Run()
0
#if INTERACTIVE
ForestFire.main [|""|]
#else
[<System.STAThread>]
[<EntryPoint>]
let main args = ForestFire.main args
#endif
Factor
USING: combinators grouping kernel literals math math.matrices
math.vectors prettyprint random raylib.ffi sequences ;
IN: rosetta-code.forest-fire
! The following private vocab builds up to a useful combinator,
! matrix-map-neighbors, which takes a matrix, a quotation, and
! inside the quotation makes available each element of the
! matrix as well as its neighbors, mapping the result of the
! quotation to a new matrix.
<PRIVATE
CONSTANT: neighbors {
{ -1 -1 } { -1 0 } { -1 1 }
{ 0 -1 } { 0 1 }
{ 1 -1 } { 1 0 } { 1 1 }
}
: ?i,j ( i j matrix -- elt/f ) swapd ?nth ?nth ;
: ?i,jths ( seq matrix -- newseq )
[ [ first2 ] dip ?i,j ] curry map ;
: neighbor-coords ( loc -- seq )
[ neighbors ] dip [ v+ ] curry map ;
: get-neighbors ( loc matrix -- seq )
[ neighbor-coords ] dip ?i,jths ;
: matrix>neighbors ( matrix -- seq )
dup dim matrix-coordinates concat
[ swap get-neighbors sift ] with map ;
: matrix-map-neighbors ( ... matrix quot: ( ... neighbors elt -- ... newelt ) -- ... newmatrix )
[ [ dim first ] [ matrix>neighbors ] [ concat ] tri ] dip
2map swap group ; inline
PRIVATE>
! ##### Simulation code #####
! In our forest,
! 0 = empty
! 1 = tree
! 2 = fire
CONSTANT: ignite-probability 1/12000
CONSTANT: grow-probability 1/100
: make-forest ( m n probability -- matrix )
[ random-unit > 1 0 ? ] curry make-matrix ;
: ?ignite ( -- 1/2 ) ignite-probability random-unit > 2 1 ? ;
: ?grow ( -- 0/1 ) grow-probability random-unit > 1 0 ? ;
: next-plot ( neighbors elt -- n )
{
{ [ dup 2 = ] [ 2drop 0 ] }
{ [ 2dup [ [ 2 = ] any? ] [ 1 = ] bi* and ] [ 2drop 2 ] }
{ [ 1 = ] [ drop ?ignite ] }
[ drop ?grow ]
} cond ;
: next-forest ( forest -- newforest )
[ next-plot ] matrix-map-neighbors ;
! ##### Display code #####
CONSTANT: colors ${ GRAY GREEN RED }
: draw-forest ( matrix -- )
dup dim matrix-coordinates [ concat ] bi@ swap [
[ first2 [ 5 * ] bi@ 5 5 ] dip colors nth draw-rectangle
] 2each ;
500 500 "Forest Fire" init-window 100 100 1/2 make-forest
60 set-target-fps
[ window-should-close ] [
begin-drawing
BLACK clear-background dup draw-forest
end-drawing
next-forest
] until drop close-window
- Output:
Forth
30 CONSTANT WIDTH
30 CONSTANT HEIGHT
WIDTH HEIGHT * CONSTANT SIZE
1 VALUE SEED
: (RAND) ( -- u) \ xorshift generator
SEED DUP 13 LSHIFT XOR
DUP 17 RSHIFT XOR
DUP 5 LSHIFT XOR
DUP TO SEED ;
10000 CONSTANT RANGE
100 CONSTANT GROW
1 CONSTANT BURN
: RAND ( -- u) (RAND) RANGE MOD ;
\ Create buffers for world state
CREATE A SIZE ALLOT A SIZE ERASE
CREATE B SIZE ALLOT B SIZE ERASE
0 CONSTANT NONE 1 CONSTANT TREE 2 CONSTANT FIRE
: NEARBY-FIRE? ( addr u -- t|f)
2 -1 DO
2 -1 DO
J WIDTH * I + OVER + \ calculate an offset
DUP 0> OVER SIZE < AND IF
>R OVER R> + C@ \ fetch state of the offset cell
FIRE = IF UNLOOP UNLOOP DROP DROP TRUE EXIT THEN
ELSE DROP THEN
LOOP
LOOP DROP DROP FALSE ;
: GROW? RAND GROW <= ; \ spontaneously sprout?
: BURN? RAND BURN <= ; \ spontaneously combust?
: STEP ( prev next --) \ Given state in PREV, put next in NEXT
>R 0 BEGIN DUP SIZE <
WHILE
2DUP + C@ CASE
FIRE OF NONE ENDOF
TREE OF 2DUP NEARBY-FIRE? BURN? OR IF FIRE ELSE TREE THEN ENDOF
NONE OF GROW? IF TREE ELSE NONE THEN ENDOF
ENDCASE
( i next-cell-state) OVER R@ + C! \ commit to next
1+ REPEAT R> DROP DROP DROP ;
: (ESCAPE) 27 EMIT [CHAR] [ EMIT ;
: ESCAPE" POSTPONE (ESCAPE) POSTPONE S" POSTPONE TYPE ; IMMEDIATE
: CLEAR ESCAPE" H" ;
: RETURN ESCAPE" E" ;
: RESET ESCAPE" m" ;
: .FOREST ( addr --) CLEAR
HEIGHT 0 DO
WIDTH 0 DO
DUP C@ CASE
NONE OF SPACE ENDOF
TREE OF ESCAPE" 32m" [CHAR] T EMIT RESET ENDOF
FIRE OF ESCAPE" 31m" [CHAR] # EMIT RESET ENDOF
ENDCASE 1+
LOOP RETURN
LOOP RESET DROP ;
: (GO) ( buffer buffer' -- buffer' buffer)
2DUP STEP \ step the simulation
DUP .FOREST \ print the current state
SWAP ; \ prepare for next iteration
: GO A B BEGIN (GO) AGAIN ;
Fortran
module ForestFireModel
implicit none
type :: forestfire
integer, dimension(:,:,:), allocatable :: field
integer :: width, height
integer :: swapu
real :: prob_tree, prob_f, prob_p
end type forestfire
integer, parameter :: &
empty = 0, &
tree = 1, &
burning = 2
private :: bcheck, set, oget, burning_neighbor ! cset, get
contains
! create and initialize the field(s)
function forestfire_new(w, h, pt, pf, pp) result(res)
type(forestfire) :: res
integer, intent(in) :: w, h
real, intent(in), optional :: pt, pf, pp
integer :: i, j
real :: r
allocate(res%field(2,w,h)) ! no error check
res%prob_tree = 0.5
res%prob_f = 0.00001
res%prob_p = 0.001
if ( present(pt) ) res%prob_tree = pt
if ( present(pf) ) res%prob_f = pf
if ( present(pp) ) res%prob_p = pp
res%width = w
res%height = h
res%swapu = 0
res%field = empty
do i = 1,w
do j = 1,h
call random_number(r)
if ( r <= res%prob_tree ) call cset(res, i, j, tree)
end do
end do
end function forestfire_new
! destroy the field(s)
subroutine forestfire_destroy(f)
type(forestfire), intent(inout) :: f
if ( allocated(f%field) ) deallocate(f%field)
end subroutine forestfire_destroy
! evolution
subroutine forestfire_evolve(f)
type(forestfire), intent(inout) :: f
integer :: i, j
real :: r
do i = 1, f%width
do j = 1, f%height
select case ( get(f, i, j) )
case (burning)
call set(f, i, j, empty)
case (empty)
call random_number(r)
if ( r > f%prob_p ) then
call set(f, i, j, empty)
else
call set(f, i, j, tree)
end if
case (tree)
if ( burning_neighbor(f, i, j) ) then
call set(f, i, j, burning)
else
call random_number(r)
if ( r > f%prob_f ) then
call set(f, i, j, tree)
else
call set(f, i, j, burning)
end if
end if
end select
end do
end do
f%swapu = ieor(f%swapu, 1)
end subroutine forestfire_evolve
! helper funcs/subs
subroutine set(f, i, j, t)
type(forestfire), intent(inout) :: f
integer, intent(in) :: i, j, t
if ( bcheck(f, i, j) ) then
f%field(ieor(f%swapu,1), i, j) = t
end if
end subroutine set
subroutine cset(f, i, j, t)
type(forestfire), intent(inout) :: f
integer, intent(in) :: i, j, t
if ( bcheck(f, i, j) ) then
f%field(f%swapu, i, j) = t
end if
end subroutine cset
function bcheck(f, i, j)
logical :: bcheck
type(forestfire), intent(in) :: f
integer, intent(in) :: i, j
bcheck = .false.
if ( (i >= 1) .and. (i <= f%width) .and. &
(j >= 1) .and. (j <= f%height) ) bcheck = .true.
end function bcheck
function get(f, i, j) result(r)
integer :: r
type(forestfire), intent(in) :: f
integer, intent(in) :: i, j
if ( .not. bcheck(f, i, j) ) then
r = empty
else
r = f%field(f%swapu, i, j)
end if
end function get
function oget(f, i, j) result(r)
integer :: r
type(forestfire), intent(in) :: f
integer, intent(in) :: i, j
if ( .not. bcheck(f, i, j) ) then
r = empty
else
r = f%field(ieor(f%swapu,1), i, j)
end if
end function oget
function burning_neighbor(f, i, j) result(r)
logical :: r
type(forestfire), intent(in) :: f
integer, intent(in) :: i, j
integer, dimension(3,3) :: s
s = f%field(f%swapu, i-1:i+1, j-1:j+1)
s(2,2) = empty
r = any(s == burning)
end function burning_neighbor
subroutine forestfire_print(f)
type(forestfire), intent(in) :: f
integer :: i, j
do j = 1, f%height
do i = 1, f%width
select case(get(f, i, j))
case (empty)
write(*,'(A)', advance='no') '.'
case (tree)
write(*,'(A)', advance='no') 'Y'
case (burning)
write(*,'(A)', advance='no') '*'
end select
end do
write(*,*)
end do
end subroutine forestfire_print
end module ForestFireModel
program ForestFireTest
use ForestFireModel
implicit none
type(forestfire) :: f
integer :: i
f = forestfire_new(74, 40)
do i = 1, 1001
write(*,'(A)', advance='no') achar(z'1b') // '[H' // achar(z'1b') // '[2J'
call forestfire_print(f)
call forestfire_evolve(f)
end do
call forestfire_destroy(f)
end program ForestFireTest
Go
Text. The program prints the configuration, waits for the Enter key, and prints the next. It makes a pretty good animation to just hold down the Enter key.
package main
import (
"fmt"
"math/rand"
"strings"
)
const (
rows = 20
cols = 30
p = .01
f = .001
)
const rx = rows + 2
const cx = cols + 2
func main() {
odd := make([]byte, rx*cx)
even := make([]byte, rx*cx)
for r := 1; r <= rows; r++ {
for c := 1; c <= cols; c++ {
if rand.Intn(2) == 1 {
odd[r*cx+c] = 'T'
}
}
}
for {
print(odd)
step(even, odd)
fmt.Scanln()
print(even)
step(odd, even)
fmt.Scanln()
}
}
func print(model []byte) {
fmt.Println(strings.Repeat("__", cols))
fmt.Println()
for r := 1; r <= rows; r++ {
for c := 1; c <= cols; c++ {
if model[r*cx+c] == 0 {
fmt.Print(" ")
} else {
fmt.Printf(" %c", model[r*cx+c])
}
}
fmt.Println()
}
}
func step(dst, src []byte) {
for r := 1; r <= rows; r++ {
for c := 1; c <= cols; c++ {
x := r*cx + c
dst[x] = src[x]
switch dst[x] {
case '#':
// rule 1. A burning cell turns into an empty cell
dst[x] = 0
case 'T':
// rule 2. A tree will burn if at least one neighbor is burning
if src[x-cx-1]=='#' || src[x-cx]=='#' || src[x-cx+1]=='#' ||
src[x-1] == '#' || src[x+1] == '#' ||
src[x+cx-1]=='#' || src[x+cx]=='#' || src[x+cx+1] == '#' {
dst[x] = '#'
// rule 3. A tree ignites with probability f
// even if no neighbor is burning
} else if rand.Float64() < f {
dst[x] = '#'
}
default:
// rule 4. An empty space fills with a tree with probability p
if rand.Float64() < p {
dst[x] = 'T'
}
}
}
}
}
Haskell
import Control.Monad (replicateM, unless)
import Data.List (tails, transpose)
import System.Random (randomRIO)
data Cell
= Empty
| Tree
| Fire
deriving (Eq)
instance Show Cell where
show Empty = " "
show Tree = "T"
show Fire = "$"
randomCell :: IO Cell
randomCell = fmap ([Empty, Tree] !!) (randomRIO (0, 1) :: IO Int)
randomChance :: IO Double
randomChance = randomRIO (0, 1.0) :: IO Double
rim :: a -> [[a]] -> [[a]]
rim b = fmap (fb b) . (fb =<< rb)
where
fb = (.) <$> (:) <*> (flip (++) . return)
rb = fst . unzip . zip (repeat b) . head
take3x3 :: [[a]] -> [[[a]]]
take3x3 = concatMap (transpose . fmap take3) . take3
where
take3 = init . init . takeWhile (not . null) . fmap (take 3) . tails
list2Mat :: Int -> [a] -> [[a]]
list2Mat n = takeWhile (not . null) . fmap (take n) . iterate (drop n)
evolveForest :: Int -> Int -> Int -> IO ()
evolveForest m n k = do
let s = m * n
fs <- replicateM s randomCell
let nextState xs = do
ts <- replicateM s randomChance
vs <- replicateM s randomChance
let rv [r1, [l, c, r], r3] newTree fire
| c == Fire = Empty
| c == Tree && Fire `elem` concat [r1, [l, r], r3] = Fire
| c == Tree && 0.01 >= fire = Fire
| c == Empty && 0.1 >= newTree = Tree
| otherwise = c
return $ zipWith3 rv xs ts vs
evolve i xs =
unless (i > k) $
do let nfs = nextState $ take3x3 $ rim Empty $ list2Mat n xs
putStrLn ("\n>>>>>> " ++ show i ++ ":")
mapM_ (putStrLn . concatMap show) $ list2Mat n xs
nfs >>= evolve (i + 1)
evolve 1 fs
main :: IO ()
main = evolveForest 6 50 3
- Output:
Sample
>>>>>> 1:
TTT TT TT TTT T TTT T TT T TT TTTT
TTTT T T TT T T TTTTTTT T T TT T TT TT
TTTT TT T TTTT T TT T TTTT T TT TT TT T T TTT
T TT TTTT TTT TTT TT TT TTTTTT TTTT T TTT TTT
T T TTT T T T TT T TT TT TT T TTT TT
T T TTT TT TT T TT TTTTT TT TT T
>>>>>> 2:
TTT TT TT TTT T TTT T T TT T T$ TTTT
TTTT T T TTTT T T TTTTTTT T TT TT T TTT TT
TTTT TT T TTTT T TT T TTTT TTT$ TT TT TT T TTT
T TTTTTTT TTT TTTTTT TT TTTTTTT TTTT TTTTT TTT
TTT TTTT TT T T TT T TT TT TT T TTT TT
T T T TTT TT TT T TT TTTTT TT TTT T
>>>>>> 3:
TTT TT TT TTT T TTT T T TT T $ TTTTTT
TTTT T T TTTT T TT TTTTTTTTT T $T T$T$ TTT TT
TTTT TT T TTTT T TT T TTTT TT$ TT TT TT T TTT
T TTTTTTTT TTT TTTTTT TT TTTTTT$ $TTT TTTTT TTT
TTT TTTT TT T T TT TT T TT TT TT T TTT TT
T T T TTT TT TT T T TT TTTTTT TT TTT T
Icon and Unicon
printf.icn provides printf graphics.icn provides graphics
J
NB. states: 0 empty, 1 tree, _1 fire
dims =:10 10
tessellate=: 0,0,~0,.0,.~ 3 3 >./@,;._3 ]
mask=: tessellate dims$1
chance=: 1 :'(> ? bind (dims$0)) bind (mask*m)'
start=: 0.5 chance
grow =: 0.01 chance
fire =: 0.001 chance
spread=: [: tessellate 0&>
step=: grow [`]@.(|@])"0 >.&0 * _1 ^ fire +. spread
run=:3 :0
forest=. start''
for.i.y do.
smoutput ' #o' {~ forest=. step forest
end.
)
Example use:
run 2
##### #
# #
### ####
# # # #
##### #
## # #
# #
o## #
##### #
# #
### ####
# # # #
##### #
## # #
o #
o# #
Note that I have used an artificially small grid here, and that I ran this several times until I could find one that had a fire from the start. Also, the current revision of this code does not show the starting state, though that would be easily changed.
Also, currently the parameters defining the size of the forest, and the probabilities are hard coded into the program and you need to rerun the program's script when they change.
Finally note that the grid size includes the one cell "border" which are blank. If the border cells are meant to be outside of the represented dimensions, you can add 2 to them (or change the code to do so).
JAMES II/Rule-based Cellular Automata
@caversion 1;
dimensions 2;
state EMPTY, TREE, BURNING;
// an empty cell grows a tree with a chance of p = 5 %
rule{EMPTY} [0.05] : -> TREE;
// a burning cell turns to a burned cell
rule{BURNING}: -> EMPTY;
// a tree starts burning if there is at least one neighbor burning
rule{TREE} : BURNING{1,} -> BURNING;
// a tree is hit by lightning with a change of f = 0.006 %
rule{TREE} [0.00006] : -> BURNING;The starting configuration cannot be given in the modeling language since the concepts of the model and its parameters (which includes the starting configuration) are separate in JAMES II.
Java
Text
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
public class Fire {
private static final char BURNING = 'w'; //w looks like fire, right?
private static final char TREE = 'T';
private static final char EMPTY = '.';
private static final double F = 0.2;
private static final double P = 0.4;
private static final double TREE_PROB = 0.5;
private static List<String> process(List<String> land){
List<String> newLand = new LinkedList<String>();
for(int i = 0; i < land.size(); i++){
String rowAbove, thisRow = land.get(i), rowBelow;
if(i == 0){//first row
rowAbove = null;
rowBelow = land.get(i + 1);
}else if(i == land.size() - 1){//last row
rowBelow = null;
rowAbove = land.get(i - 1);
}else{//middle
rowBelow = land.get(i + 1);
rowAbove = land.get(i - 1);
}
newLand.add(processRows(rowAbove, thisRow, rowBelow));
}
return newLand;
}
private static String processRows(String rowAbove, String thisRow,
String rowBelow){
String newRow = "";
for(int i = 0; i < thisRow.length();i++){
switch(thisRow.charAt(i)){
case BURNING:
newRow+= EMPTY;
break;
case EMPTY:
newRow+= Math.random() < P ? TREE : EMPTY;
break;
case TREE:
String neighbors = "";
if(i == 0){//first char
neighbors+= rowAbove == null ? "" : rowAbove.substring(i, i + 2);
neighbors+= thisRow.charAt(i + 1);
neighbors+= rowBelow == null ? "" : rowBelow.substring(i, i + 2);
if(neighbors.contains(Character.toString(BURNING))){
newRow+= BURNING;
break;
}
}else if(i == thisRow.length() - 1){//last char
neighbors+= rowAbove == null ? "" : rowAbove.substring(i - 1, i + 1);
neighbors+= thisRow.charAt(i - 1);
neighbors+= rowBelow == null ? "" : rowBelow.substring(i - 1, i + 1);
if(neighbors.contains(Character.toString(BURNING))){
newRow+= BURNING;
break;
}
}else{//middle
neighbors+= rowAbove == null ? "" : rowAbove.substring(i - 1, i + 2);
neighbors+= thisRow.charAt(i + 1);
neighbors+= thisRow.charAt(i - 1);
neighbors+= rowBelow == null ? "" : rowBelow.substring(i - 1, i + 2);
if(neighbors.contains(Character.toString(BURNING))){
newRow+= BURNING;
break;
}
}
newRow+= Math.random() < F ? BURNING : TREE;
}
}
return newRow;
}
public static List<String> populate(int width, int height){
List<String> land = new LinkedList<String>();
for(;height > 0; height--){//height is just a copy anyway
StringBuilder line = new StringBuilder(width);
for(int i = width; i > 0; i--){
line.append((Math.random() < TREE_PROB) ? TREE : EMPTY);
}
land.add(line.toString());
}
return land;
}
//process the land n times
public static void processN(List<String> land, int n){
for(int i = 0;i < n; i++){
land = process(land);
}
}
//process the land n times and print each step along the way
public static void processNPrint(List<String> land, int n){
for(int i = 0;i < n; i++){
land = process(land);
print(land);
}
}
//print the land
public static void print(List<String> land){
for(String row: land){
System.out.println(row);
}
System.out.println();
}
public static void main(String[] args){
List<String> land = Arrays.asList(".TTT.T.T.TTTT.T",
"T.T.T.TT..T.T..",
"TT.TTTT...T.TT.",
"TTT..TTTTT.T..T",
".T.TTT....TT.TT",
"...T..TTT.TT.T.",
".TT.TT...TT..TT",
".TT.T.T..T.T.T.",
"..TTT.TT.T..T..",
".T....T.....TTT",
"T..TTT..T..T...",
"TTT....TTTTTT.T",
"......TwTTT...T",
"..T....TTTTTTTT",
".T.T.T....TT...");
print(land);
processNPrint(land, 10);
System.out.println("Random land test:");
land = populate(10, 10);
print(land);
processNPrint(land, 10);
}
}
Graphics
See: Forest fire/Java/Graphics
JavaScript
JavaScript Node
Functional approach using lodash
"use strict"
const _ = require('lodash');
const WIDTH_ARGUMENT_POSITION = 2;
const HEIGHT_ARGUMENT_POSITION = 3;
const TREE_PROBABILITY = 0.5;
const NEW_TREE_PROBABILITY = 0.01;
const BURN_PROBABILITY = 0.0001;
const CONSOLE_RED = '\x1b[31m';
const CONSOLE_GREEN = '\x1b[32m';
const CONSOLE_COLOR_CLOSE = '\x1b[91m';
const CONSOLE_CLEAR = '\u001B[2J\u001B[0;0f';
const NEIGHBOURS = [
[-1, -1],
[-1, 0],
[-1, 1],
[ 0, -1],
[ 0, 1],
[ 1, -1],
[ 1, 0],
[ 1, 1]
];
const PRINT_DECODE = {
' ': ' ',
'T': `${CONSOLE_GREEN}T${CONSOLE_COLOR_CLOSE}`,
'B': `${CONSOLE_RED}T${CONSOLE_COLOR_CLOSE}`,
};
const CONDITIONS = {
'T': (forest, y, x) => Math.random() < BURN_PROBABILITY || burningNeighbour(forest, y, x) ? 'B' : 'T',
' ': () => Math.random() < NEW_TREE_PROBABILITY ? 'T' : ' ',
'B': () => ' '
};
const WIDTH = process.argv[WIDTH_ARGUMENT_POSITION] || 20;
const HEIGHT = process.argv[HEIGHT_ARGUMENT_POSITION] || 10;
const update = forest => {
return _.map(forest, (c, ci) => {
return _.map(c, (r, ri) => {
return CONDITIONS[r](forest, ci, ri);
});
});
}
const printForest = forest => {
process.stdout.write(CONSOLE_CLEAR);
_.each(forest, c => {
_.each(c, r => {
process.stdout.write(PRINT_DECODE[r]);
});
process.stdout.write('\n');
})
}
const burningNeighbour = (forest, y, x) => {
return _(NEIGHBOURS)
.map(n => _.isUndefined(forest[y + n[0]]) ? null : forest[y + n[0]][x + n[1]])
.any(_.partial(_.isEqual, 'B'));
};
let forest = _.times(HEIGHT, () => _.times(WIDTH, () => Math.random() < TREE_PROBABILITY ? 'T' : ' '));
setInterval(() => {
forest = update(forest);
printForest(forest)
}, 20);
JavaScript
var forest = {
X: 50,
Y: 50,
propTree: 0.5,
propTree2: 0.01,
propBurn: 0.0001,
t: [],
c: ['rgb(255,255,255)', 'rgb(0,255,0)', 'rgb(255,0,0)']
};
for(var i = 0; i < forest.Y; i++) {
forest.t[i] = [];
for(var j = 0; j < forest.Y; j++) {
forest.t[i][j] = Math.random() < forest.propTree ? 1 : 0;
}
}
function afterLoad(forest) {
var canvas = document.getElementById('canvas');
var c = canvas.getContext('2d');
for(var i = 0; i < forest.X; i++) {
for(var j = 0; j < forest.Y; j++) {
c.fillStyle = forest.c[forest.t[i][j]];
c.fillRect(10*j, 10*i, 10*j+9, 10*i+9);
}
}
}
function doStep(forest) {
var to = [];
for(var i = 0; i < forest.Y; i++) {
to[i] = forest.t[i].slice(0);
}
//indices outside the array are undefined; which converts to 0=empty on forced typecast
for(var i = 0; i < forest.Y; i++) {
for(var j = 0; j < forest.Y; j++) {
if(0 == to[i][j]) {
forest.t[i][j] = Math.random() < forest.propTree2 ? 1 : 0;
} else if(1 == to[i][j]) {
if(
((i>0) && (2 == to[i-1][j])) ||
((i<forest.Y-1) && (2 == to[i+1][j])) ||
((j>0) && (2 == to[i][j-1])) ||
((j<forest.X-1) && (2 == to[i][j+1]))
) {
forest.t[i][j] = 2;
} else {
forest.t[i][j] = Math.random() < forest.propBurn ? 2 : 1;
}
} else if(2 == to[i][j]) {
//If it burns, it gets empty ...
forest.t[i][j] = 0;
}
}
}
}
window.setInterval(function(){
doStep(forest);
afterLoad(forest);
}, 100);
To actually see it work we need a small demo page with HTML5 compliant code:
<!DOCTYPE html>
<html>
<head>
<title>Forest Fire</title>
</head>
<body>
<canvas id="canvas" width="500" height="500">
Your browser doesn't support HTML5 Canvas.
</canvas>
<script language="JavaScript">//<![CDATA[<!--
// --> HERE COMES THE SCRIPT FROM ABOVE <--
//-->]]></script>
</body>
</html>
The output is a (mostly fluent) animation of the area.
Julia
using Printf
@enum State empty tree fire
function evolution(nepoch::Int=100, init::Matrix{State}=fill(tree, 30, 50))
# Single evolution
function evolve!(forest::Matrix{State}; f::Float64=0.12, p::Float64=0.5)
dir = [-1 -1; -1 0; -1 1; 0 -1; 0 1; 1 -1; 1 0; 1 1]
# A tree will burn if at least one neighbor is burning
for i in 1:size(forest, 1), j in 1:size(forest, 2)
for k in 1:size(dir, 1)
if checkbounds(Bool, forest, i + dir[k, 1], j + dir[k, 2]) &&
get(forest, i + dir[k, 1], j + dir[k, 2]) == fire
forest[i, j] = fire
break
end
end
end
for i in LinearIndices(forest)
# A burning cell turns into an empty cell
if forest[i] == fire forest[i] = empty end
# A tree ignites with probability f even if no neighbor is burning
if forest[i] == tree && rand() < f forest[i] = fire end
# An empty space fills with a tree with probability p
if forest[i] == empty && rand() < p forest[i] = tree end
end
end
# Print functions
function printforest(f::Matrix{State})
for i in 1:size(f, 1)
for j in 1:size(f, 2)
print(f[i, j] == empty ? ' ' : f[i, j] == tree ? '🌲' : '🔥')
end
println()
end
end
function printstats(f::Matrix{State})
tot = length(f)
nt = count(x -> x in (tree, fire), f)
nb = count(x -> x == fire, f)
@printf("\n%6i cell(s), %6i tree(s), %6i currently burning (%6.2f%%, %6.2f%%)\n",
tot, nt, nb, nt / tot * 100, nb / nt * 100)
end
# Main
printforest(init)
printstats(init)
for i in 1:nepoch
# println("\33[2J")
evolve!(init)
# printforest(init)
# printstats(init)
# sleep(1)
end
printforest(init)
printstats(init)
end
evolution()
- Output:
Final output (epoch 100):
🌲🌲🔥🌲 🌲🌲🌲🌲 🔥🌲🌲🔥🌲🌲🌲🌲🌲🔥🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲 🌲🌲🌲🔥 🌲🌲🌲🌲🔥🌲🌲
🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲 🔥🌲🌲 🌲🌲🔥🔥🌲🌲 🌲🌲🌲 🌲🌲🌲🌲
🌲🌲🌲🌲🌲🔥🔥🌲 🌲🌲🌲 🔥🔥🌲🌲🌲 🌲 🌲🌲🌲🌲🌲🌲🌲🌲🔥🌲 🌲🌲 🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲
🌲🔥🌲 🌲🌲 🌲 🌲🌲🌲🌲 🌲🌲 🌲 🌲🌲🌲 🌲🌲 🌲 🌲🔥🌲🌲🌲🔥🔥🔥🌲🌲🌲🌲🌲🌲🌲🌲🌲🔥🌲🌲
🌲🌲🌲 🔥🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🔥🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🔥🌲🌲🌲🌲🌲🌲 🌲🌲🌲 🌲🌲
🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲 🌲🌲🌲🌲🌲🌲🌲🔥🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲 🌲🌲
🌲🌲🌲 🌲🌲🌲🌲 🌲🌲 🌲🌲 🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲🔥🌲 🌲🌲🌲🌲🌲🌲 🌲🌲🌲 🌲 🔥🌲🌲🌲🌲🌲
🌲🌲🔥🔥🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲 🌲🌲🌲 🌲🌲 🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🔥🌲🌲🌲🌲
🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲🔥 🌲🌲🌲🌲 🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲
🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🔥 🔥🌲🔥🌲🌲 🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲
🌲 🔥 🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲 🌲🌲🌲🌲🌲🔥🌲 🌲 🌲🌲🌲 🌲🔥 🔥🔥🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲
🌲🌲🌲🔥🌲🌲🌲🌲🌲🌲🌲🔥🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🔥🌲🌲🔥🌲🌲 🌲 🌲🌲🌲🌲🌲🌲
🌲🌲🔥🌲🌲🌲 🌲 🔥🌲 🌲 🌲 🌲🌲🌲🔥🌲🌲🔥🌲🌲🌲🌲🔥🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲
🌲 🌲🌲 🌲🌲🌲🌲 🌲 🔥🔥🌲🌲🌲🔥 🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🔥 🌲🌲
🌲🌲🌲🔥 🌲🌲🌲🌲🔥🌲🔥🌲 🌲🌲🌲🌲🌲🌲🌲🔥🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲🔥🌲🌲
🌲🌲🌲🌲🌲 🌲🌲🌲🌲🌲🌲 🌲🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🔥🌲🔥 🌲🌲🌲🌲🌲🌲🔥 🌲🌲🌲 🔥🔥
🌲 🌲🌲🌲🌲🌲🌲🌲🔥 🌲🌲🌲🌲 🌲🌲 🌲🌲🔥🌲🌲 🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🔥🌲 🔥🌲🔥🌲
🌲🌲🌲 🌲🌲🔥 🌲🌲🌲🌲🌲🌲🌲🌲🔥🌲🌲 🌲🔥 🌲🌲 🌲🌲🌲🔥🌲🌲🔥🌲 🔥🌲 🌲🌲🌲🌲🌲🌲🌲🌲 🌲
🌲🌲🌲 🔥🌲🌲🌲🌲 🌲🌲 🌲 🌲🌲🌲 🌲🌲🌲🌲🌲 🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲 🌲🌲🌲🌲🌲🌲🌲
🌲 🌲 🌲🌲 🌲🌲 🌲🌲 🌲 🌲🌲🌲🌲🌲🌲🌲 🌲 🌲 🌲🌲🌲 🌲🌲 🌲🌲🌲🌲 🌲 🌲
🌲🌲 🌲 🌲🌲🌲 🌲🌲 🌲 🌲🌲🌲🌲🌲 🌲🌲 🌲🌲 🌲🌲 🌲🌲 🌲🌲 🌲 🌲🌲🌲
🌲🌲 🌲🌲 🌲🌲 🌲🌲 🌲🌲 🌲🌲🌲🌲🌲🌲🌲🌲🌲🌲 🌲 🌲 🌲🌲🌲 🌲
🌲🌲🌲 🌲🌲🌲🌲 🌲 🌲 🌲 🌲🌲🌲🌲🌲 🌲🌲 🌲 🌲 🌲🌲 🌲🌲 🌲 🌲🌲 🌲🌲
🌲🌲 🌲🌲🌲 🌲🌲🌲 🌲 🌲 🌲 🌲 🌲🌲 🌲 🌲🌲 🌲 🌲 🌲 🌲🌲
🌲🌲 🌲 🌲🌲🌲🌲 🌲 🌲🌲 🌲🌲🌲🌲 🌲 🌲🌲🌲🌲 🌲 🌲🌲🌲🌲
🌲🌲 🌲🌲 🌲🌲🌲🌲🌲 🌲 🌲🌲 🌲🌲🌲🌲🌲 🌲 🌲 🌲🌲🌲 🌲🌲🌲 🌲 🌲🌲 🌲 🌲
🌲 🌲🌲 🌲🌲 🌲 🌲🌲🌲🌲 🌲🌲 🌲 🌲🌲🌲 🌲🌲 🌲🌲🌲 🌲
🌲🌲 🌲🌲 🌲 🌲 🌲🌲🌲🌲🌲 🌲🌲 🌲 🌲 🌲 🌲🌲 🌲 🌲🌲🌲🌲🌲🌲 🌲🌲
🌲 🌲 🌲🌲 🌲🌲 🌲 🌲🌲 🌲🌲🌲 🌲 🌲 🌲 🌲 🌲🌲🌲🌲 🌲
🌲🌲🌲🌲🌲 🌲 🌲🌲 🌲 🌲 🌲🌲🌲 🌲🌲🌲 🌲 🌲🌲 🌲🌲 🌲 🌲🌲🌲🌲
1500 cell(s), 1089 tree(s), 73 currently burning ( 72.60%, 6.70%)
Lua
This program uses the Lua Curses library for graphics, although changing the code to avoid such dependency is easy.
-- ForestFire automaton implementation
-- Rules: at each step:
-- 1) a burning tree disappears
-- 2) a non-burning tree starts burning if any of its neighbours is
-- 3) an empty spot may generate a tree with prob P
-- 4) a non-burning tree may ignite with prob F
local socket = require 'socket' -- needed for socket.sleep
local curses = require 'curses'
local p_spawn, p_ignite = 0.005, 0.0002
local naptime = 0.03 -- seconds
local forest_x, forest_y = 60, 30
local forest = (function (x, y)
local wrl = {}
for i = 1, y do
wrl[i] = {}
for j = 1, x do
local rand = math.random()
wrl[i][j] = (rand < 0.5) and 1 or 0
end
end
return wrl
end)(forest_x, forest_y)
math.randomseed(os.time())
forest.step = function (self)
for i = 1, #self do
for j = 1, #self[i] do
if self[i][j] == 0 then
if math.random() < p_spawn then self[i][j] = 1 end
elseif self[i][j] == 1 then
if self:ignite(i, j) or math.random() < p_ignite then self[i][j] = 2 end
elseif self[i][j] == 2 then self[i][j] = 0
else error("Error: forest[" .. i .. "][" .. j .. "] is " .. self[i][j] .. "!")
end
end
end
end
forest.draw = function (self)
for i = 1, #self do
for j = 1, #self[i] do
if self[i][j] == 0 then win:mvaddch(i,j," ")
elseif self[i][j] == 1 then
win:attron(curses.color_pair(1))
win:mvaddch(i,j,"Y")
win:attroff(curses.color_pair(1))
elseif self[i][j] == 2 then
win:attron(curses.color_pair(2))
win:mvaddch(i,j,"#")
win:attroff(curses.color_pair(2))
else error("self[" .. i .. "][" .. j .. "] is " .. self[i][j] .. "!")
end
end
end
end
forest.ignite = function (self, i, j)
for k = i - 1, i + 1 do
if k < 1 or k > #self then goto continue1 end
for l = j - 1, j + 1 do
if l < 1 or
l > #self[i] or
math.abs((k - i) + (l - j)) ~= 1
then
goto continue2
end
if self[k][l] == 2 then return true end
::continue2::
end
::continue1::
end
return false
end
local it = 1
curses.initscr()
curses.start_color()
curses.echo(false)
curses.init_pair(1, curses.COLOR_GREEN, curses.COLOR_BLACK)
curses.init_pair(2, curses.COLOR_RED, curses.COLOR_BLACK)
win = curses.newwin(forest_y + 2, forest_x, 0, 0)
win:clear()
win:mvaddstr(forest_y + 1, 0, "p_spawn = " .. p_spawn .. ", p_ignite = " .. p_ignite)
repeat
forest:draw()
win:move(forest_y, 0)
win:clrtoeol()
win:addstr("Iteration: " .. it .. ", nap = " .. naptime*1000 .. "ms")
win:refresh()
forest:step()
it = it + 1
socket.sleep(naptime)
until false
Mathematica / Wolfram Language
Mathematica is good at working with cellular automata -- especially 2-color 1-dimensional cellular automata. The automaton function is awkward yet very powerful. This code implements a 3-color 2-dimensional cellular automaton with 9-cell neighbourhoods using a custom cell evolution function. There is probably a rule number specification that can replace the custom evolution function and make this simpler and faster. But this works well enough. The last line of code plots the state of the forest after the 300th step.
evolve[nbhd_List, k_] := 0 /; nbhd