Barnsley fern: Difference between revisions
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set(m, n, "#00ff00")</syntaxhighlight>
=={{header|Prolog}}==
<syntaxhighlight lang="prolog>
% a straight forward adaption from the Ada example
% these imports are needed for Ciao Prolog but needed
% modules will vary with your Prolog system
:- use_module(library(streams)).
:- use_module(library(stream_utils)).
:- use_module(library(lists)).
:- use_module(library(llists)).
:- use_module(library(hiordlib)).
:- use_module(library(random)).
:- use_module(library(format)).
replicate(Term, Times, L) :-
length(L, Times),
maplist(=(Term), L).
replace(0, [_|T], E, [E|T]).
replace(X, [H|T0], E, [H|T]) :-
X0 is X -1,
replace(X0, T0, E, T).
replace_2d(X, 0, [H|T], E, [R|T]) :-
replace(X, H, E, R).
replace_2d(X, Y, [H|T0], E, [H|T]) :-
Y0 is Y -1,
replace_2d(X, Y0, T0, E, T).
fern_iteration(10000, _X, _Y, Final, Final).
fern_iteration(N, X, Y, I, Final) :-
random(R),
( R =< 0.01
-> ( X1 is 0.0,
Y1 is 0.16*Y )
; ( R =< 0.86
-> ( X1 is 0.85*X + 0.04*Y,
Y1 is -0.04*X + 0.85*Y + 1.6 )
; ( R =< 0.93
-> ( X1 is 0.20*X - 0.26*Y,
Y1 is 0.23*X + 0.22*Y + 1.60 )
; ( X1 is -0.15*X + 0.28*Y,
Y1 is 0.26*X + 0.24*Y + 0.44 )
) ) ),
PointX is 250 + floor(70.0*X1),
PointY is 750 - floor(70.0*Y1),
replace_2d(PointX, PointY, I, [0, 255, 0], I1), !,
N1 is N + 1,
fern_iteration(N1, X1, Y1, I1, Final).
draw_fern :-
replicate([0, 0, 0], 500, Row),
replicate(Row, 750, F),
fern_iteration(0, 0, 0, F, Fern),
% the following lines are written for ciao prolog and
% write to a ppm6 file for viewing
% adapting to SWI or Scryer should be straighforward
open('fern.ppm', write, File),
flatten(Fern, FP),
format(File, "P6\n~d ~d\n255\n", [500, 750]),
write_bytes(File, FP),
close(File).
</syntaxhighlight>
=={{header|PureBasic}}==
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