Bitmap/Midpoint circle algorithm
From Rosetta Code
< Bitmap
You are encouraged to solve this task according to the task description, using any language you may know.
Contents |
[edit] Ada
procedure Circle
( Picture : in out Image;
Center : Point;
Radius : Natural;
Color : Pixel
) is
F : Integer := 1 - Radius;
ddF_X : Integer := 0;
ddF_Y : Integer := -2 * Radius;
X : Integer := 0;
Y : Integer := Radius;
begin
Picture (Center.X, Center.Y + Radius) := Color;
Picture (Center.X, Center.Y - Radius) := Color;
Picture (Center.X + Radius, Center.Y) := Color;
Picture (Center.X - Radius, Center.Y) := Color;
while X < Y loop
if F >= 0 then
Y := Y - 1;
ddF_Y := ddF_Y + 2;
F := F + ddF_Y;
end if;
X := X + 1;
ddF_X := ddF_X + 2;
F := F + ddF_X + 1;
Picture (Center.X + X, Center.Y + Y) := Color;
Picture (Center.X - X, Center.Y + Y) := Color;
Picture (Center.X + X, Center.Y - Y) := Color;
Picture (Center.X - X, Center.Y - Y) := Color;
Picture (Center.X + Y, Center.Y + X) := Color;
Picture (Center.X - Y, Center.Y + X) := Color;
Picture (Center.X + Y, Center.Y - X) := Color;
Picture (Center.X - Y, Center.Y - X) := Color;
end loop;
end Circle;
The following illustrates use:
X : Image (1..16, 1..16);
begin
Fill (X, White);
Circle (X, (8, 8), 5, Black);
Print (X);
Sample output:
HHHHH
H H
H H
H H
H H
H H
H H
H H
H H
H H
HHHHH
[edit] ALGOL 68
Translation of: Ada
Works with: ALGOL 68 version Standard - pragmat read is an extension Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9.i386
PRAGMAT READ "Basic_bitmap_storage.a68" PRAGMAT;
circle OF class image :=
( REF IMAGE picture,
POINT center,
INT radius,
PIXEL color
)VOID:
BEGIN
INT f := 1 - radius,
POINT ddf := (0, -2 * radius),
df := (0, radius);
picture [x OF center, y OF center + radius] :=
picture [x OF center, y OF center - radius] :=
picture [x OF center + radius, y OF center] :=
picture [x OF center - radius, y OF center] := color;
WHILE x OF df < y OF df DO
IF f >= 0 THEN
y OF df -:= 1;
y OF ddf +:= 2;
f +:= y OF ddf
FI;
x OF df +:= 1;
x OF ddf +:= 2;
f +:= x OF ddf + 1;
picture [x OF center + x OF df, y OF center + y OF df] :=
picture [x OF center - x OF df, y OF center + y OF df] :=
picture [x OF center + x OF df, y OF center - y OF df] :=
picture [x OF center - x OF df, y OF center - y OF df] :=
picture [x OF center + y OF df, y OF center + x OF df] :=
picture [x OF center - y OF df, y OF center + x OF df] :=
picture [x OF center + y OF df, y OF center - x OF df] :=
picture [x OF center - y OF df, y OF center - x OF df] := color
OD
END # circle #;
#
The following illustrates use:
#
IF test THEN
REF IMAGE x = INIT LOC [1:16, 1:16] PIXEL;
(fill OF class image)(x, (white OF class image));
(circle OF class image)(x, (8, 8), 5, (black OF class image));
(print OF class image)(x)
FI
Output:
ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffff000000000000000000000000000000ffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffffffffff ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff ffffffffffff000000ffffffffffffffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffff ffffffffffffffffff000000ffffffffffffffffffffffffffffffffffffffffff000000ffffffffffffffffffffffff ffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff000000ffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffff000000000000000000000000000000ffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
[edit] C
Interface:
void raster_circle(
image img,
unsigned int x0,
unsigned int y0,
unsigned int radius,
color_component r,
color_component g,
color_component b );
Implementation:
#define plot(x, y) put_pixel_clip(img, x, y, r, g, b)
void raster_circle(
image img,
unsigned int x0,
unsigned int y0,
unsigned int radius,
color_component r,
color_component g,
color_component b )
{
int f = 1 - radius;
int ddF_x = 0;
int ddF_y = -2 * radius;
int x = 0;
int y = radius;
plot(x0, y0 + radius);
plot(x0, y0 - radius);
plot(x0 + radius, y0);
plot(x0 - radius, y0);
while(x < y)
{
if(f >= 0)
{
y--;
ddF_y += 2;
f += ddF_y;
}
x++;
ddF_x += 2;
f += ddF_x + 1;
plot(x0 + x, y0 + y);
plot(x0 - x, y0 + y);
plot(x0 + x, y0 - y);
plot(x0 - x, y0 - y);
plot(x0 + y, y0 + x);
plot(x0 - y, y0 + x);
plot(x0 + y, y0 - x);
plot(x0 - y, y0 - x);
}
}
#undef plot
[edit] Common Lisp
Based upon the OCaml version.
(defun draw-circle (draw-function x0 y0 radius)
(labels ((foo (x y)
(funcall draw-function x y))
(put (x y m)
(let ((x+ (+ x0 x))
(x- (- x0 x))
(y+ (+ y0 y))
(y- (- y0 y))
(x0y+ (+ x0 y))
(x0y- (- x0 y))
(xy0+ (+ y0 x))
(xy0- (- y0 x)))
(foo x+ y+)
(foo x+ y-)
(foo x- y+)
(foo x- y-)
(foo x0y+ xy0+)
(foo x0y+ xy0-)
(foo x0y- xy0+)
(foo x0y- xy0-)
(multiple-value-bind (y m) (if (plusp m)
(values (1- y) (- m (* 8 y)))
(values y m))
(when (<= x y)
(put (1+ x)
y
(+ m 4 (* 8 x))))))))
(put 0 radius (- 5 (* 4 radius)))
(values)))
CL-USER> (let ((buffer (make-array '(30 30)
:element-type 'bit)))
(draw-circle (lambda (x y)
(setf (bit buffer x y) 1)) 15 15 10)
buffer)
;; edited for your convenience (( ) ( 1 1 1 1 1 1 1 ) ( 1 1 1 1 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 ) ( 1 1 1 1 1 1 ) ( 1 1 1 1 1 1 1 ) ( ))
[edit] Forth
: circle { x y r color bmp -- }
1 r - 0 r 2* negate 0 r { f ddx ddy dx dy }
color x y r + bmp b!
color x y r - bmp b!
color x r + y bmp b!
color x r - y bmp b!
begin dx dy < while
f 0< 0= if
dy 1- to dy
ddy 2 + dup to ddy
f + to f
then
dx 1+ to dx
ddx 2 + dup to ddx
f 1+ + to f
color x dx + y dy + bmp b!
color x dx - y dy + bmp b!
color x dx + y dy - bmp b!
color x dx - y dy - bmp b!
color x dy + y dx + bmp b!
color x dy - y dx + bmp b!
color x dy + y dx - bmp b!
color x dy - y dx - bmp b!
repeat ;
12 12 bitmap value test
0 test bfill
6 6 5 blue test circle
test bshow cr
[edit] Fortran
This code should be inside RCImagePrimitive (see here). The private subroutine draw_circle_toch, which writes to a channel, is used by both draw_circle_rgb and draw_circle_sc and the interface allows to use draw_circle with rgb images and grayscale images.
interface draw_circle
module procedure draw_circle_sc, draw_circle_rgb
end interface
private :: plot, draw_circle_toch
subroutine plot(ch, p, v)
integer, dimension(:,:), intent(out) :: ch
type(point), intent(in) :: p
integer, intent(in) :: v
integer :: cx, cy
! I've kept the default 1-based array, but top-left corner pixel
! is labelled as (0,0).
cx = p%x + 1
cy = p%y + 1
if ( (cx > 0) .and. (cx <= ubound(ch,1)) .and. &
(cy > 0) .and. (cy <= ubound(ch,2)) ) then
ch(cx,cy) = v
end if
end subroutine plot
subroutine draw_circle_toch(ch, c, radius, v)
integer, dimension(:,:), intent(out) :: ch
type(point), intent(in) :: c
integer, intent(in) :: radius, v
integer :: f, ddf_x, ddf_y, x, y
f = 1 - radius
ddf_x = 0
ddf_y = -2 * radius
x = 0
y = radius
call plot(ch, point(c%x, c%y + radius), v)
call plot(ch, point(c%x, c%y - radius), v)
call plot(ch, point(c%x + radius, c%y), v)
call plot(ch, point(c%x - radius, c%y), v)
do while ( x < y )
if ( f >= 0 ) then
y = y - 1
ddf_y = ddf_y + 2
f = f + ddf_y
end if
x = x + 1
ddf_x = ddf_x + 2
f = f + ddf_x + 1
call plot(ch, point(c%x + x, c%y + y), v)
call plot(ch, point(c%x - x, c%y + y), v)
call plot(ch, point(c%x + x, c%y - y), v)
call plot(ch, point(c%x - x, c%y - y), v)
call plot(ch, point(c%x + y, c%y + x), v)
call plot(ch, point(c%x - y, c%y + x), v)
call plot(ch, point(c%x + y, c%y - x), v)
call plot(ch, point(c%x - y, c%y - x), v)
end do
end subroutine draw_circle_toch
subroutine draw_circle_rgb(img, c, radius, color)
type(rgbimage), intent(out) :: img
type(point), intent(in) :: c
integer, intent(in) :: radius
type(rgb), intent(in) :: color
call draw_circle_toch(img%red, c, radius, color%red)
call draw_circle_toch(img%green, c, radius, color%green)
call draw_circle_toch(img%blue, c, radius, color%blue)
end subroutine draw_circle_rgb
subroutine draw_circle_sc(img, c, radius, lum)
type(scimage), intent(out) :: img
type(point), intent(in) :: c
integer, intent(in) :: radius, lum
call draw_circle_toch(img%channel, c, radius, lum)
end subroutine draw_circle_sc
[edit] Haskell
The basic algorithm can be implemented generically.
module Circle where
import Data.List
type Point = (Int, Int)
-- Takes the center of the circle and radius, and returns the circle points
generateCirclePoints :: Point -> Int -> [Point]
generateCirclePoints (x0, y0) radius
-- Four initial points, plus the generated points
= (x0, y0 + radius) : (x0, y0 - radius) : (x0 + radius, y0) : (x0 - radius, y0) : points
where
-- Creates the (x, y) octet offsets, then maps them to absolute points in all octets.
points = concatMap generatePoints $ unfoldr step initialValues
generatePoints (x, y)
= [(xop x0 x', yop y0 y') | (x', y') <- [(x, y), (y, x)], xop <- [(+), (-)], yop <- [(+), (-)]]
-- The initial values for the loop
initialValues = (1 - radius, 1, (-2) * radius, 0, radius)
-- One step of the loop. The loop itself stops at Nothing.
step (f, ddf_x, ddf_y, x, y) | x >= y = Nothing
| otherwise = Just ((x', y'), (f', ddf_x', ddf_y', x', y'))
where
(f', ddf_y', y') | f >= 0 = (f + ddf_y' + ddf_x', ddf_y + 2, y - 1)
| otherwise = (f + ddf_x, ddf_y, y)
ddf_x' = ddf_x + 2
x' = x + 1
An example using regular 2d arrays of characters to represent a bitmap:
module CircleArrayExample where
import Circle
-- A surface is just a 2d array of characters for the purposes of this example
type Colour = Char
type Surface = Array (Int, Int) Colour
-- Returns a surface of the given width and height filled with the colour
blankSurface :: Int -> Int -> Colour -> Surface
blankSurface width height filler = listArray bounds (repeat filler)
where
bounds = ((0, 0), (width - 1, height - 1))
-- Generic plotting function. Plots points onto a surface with the given colour.
plotPoints :: Surface -> Colour -> [Point] -> Surface
plotPoints surface colour points = surface // zip points (repeat colour)
-- Draws a circle of the given colour on the surface given a center and radius
drawCircle :: Surface -> Colour -> Point -> Int -> Surface
drawCircle surface colour center radius
= plotPoints surface colour (generateCirclePoints center radius)
-- Converts a surface to a string
showSurface image = unlines [[image ! (x, y) | x <- xRange] | y <- yRange]
where
((xLow, yLow), (xHigh, yHigh)) = bounds image
(xRange, yRange) = ([xLow..xHigh], [yLow..yHigh])
-- Converts a surface to a string and prints it
printSurface = putStrLn . showSurface
Using the Image type from the Bitmap module defined here:
module CircleBitmapExample where
import Circle
import Bitmap
import Control.Monad.ST
drawCircle :: (Color c) => Image s c -> c -> Point -> Int -> ST s (Image s c)
drawCircle image colour center radius = do
let pixels = map Pixel (generateCirclePoints center radius)
forM_ pixels $ \pixel -> setPix image pixel colour
return image
[edit] J
Solution:
Using definitions from Basic bitmap storage.
NB.*getBresenhamCircle v Returns points for a circle given center and radius
NB. y is: y0 x0 radius
getBresenhamCircle=: monad define
'y0 x0 radius'=. y
x=. 0
y=. radius
f=. -. radius
pts=. 0 2$0
while. x <: y do.
pts=. pts , y , x
if. f >: 0 do.
y=. <:y
f=. f + _2 * y
end.
x=. >:x
f =. f + >: 2 * x
end.
offsets=. (,|."1) (1 _1 {~ #: i.4) *"1"1 _ pts
~.,/ (y0,x0) +"1 offsets
)
NB.*drawCircles v Draws circle(s) (x) on image (y)
NB. x is: 2-item list of boxed (y0 x0 radius) ; (color)
drawCircles=: (1&{:: ;~ [: ; [: <@getBresenhamCircle"1 (0&{::))@[ setPixels ]
Example usage:
myimg=: 0 255 0 makeRGB 25 25 NB. 25 by 25 green image
myimg=: (12 12 12 ; 255 0 0) drawCircles myimg NB. draw red circle with radius 12
viewRGB ((12 12 9 ,: 12 12 6) ; 0 0 255) drawCircles myimg NB. draw two more concentric circles
[edit] Modula-3
INTERFACE Circle;
IMPORT Bitmap;
PROCEDURE Draw(
img: Bitmap.T;
center: Bitmap.Point;
radius: CARDINAL;
color: Bitmap.Pixel);
END Circle.
MODULE Circle;
IMPORT Bitmap;
PROCEDURE Draw(
img: Bitmap.T;
center: Bitmap.Point;
radius: CARDINAL;
color: Bitmap.Pixel) =
VAR f := 1 - radius;
ddfx := 0;
ddfy := - 2 * radius;
x := 0;
y := radius;
BEGIN
Bitmap.SetPixel(img, Bitmap.Point{center.x, center.y + radius}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x, center.y - radius}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x + radius, center.y}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x - radius, center.y}, color);
WHILE x < y DO
IF f >= 0 THEN
y := y - 1;
ddfy := ddfy + 2;
f := f + ddfy;
END;
x := x + 1;
ddfx := ddfx + 2;
f := f + ddfx + 1;
Bitmap.SetPixel(img, Bitmap.Point{center.x + x, center.y + y}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x - x, center.y + y}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x + x, center.y - y}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x - x, center.y - y}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x + y, center.y + x}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x - y, center.y + x}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x + y, center.y - x}, color);
Bitmap.SetPixel(img, Bitmap.Point{center.x - y, center.y - x}, color);
END;
END Draw;
BEGIN
END Circle.
Example (outputs a PPM image):
MODULE Main;
IMPORT Circle, Bitmap, PPM;
VAR testpic: Bitmap.T;
BEGIN
testpic := Bitmap.NewImage(32, 32);
Bitmap.Fill(testpic, Bitmap.White);
Circle.Draw(testpic, Bitmap.Point{16, 16}, 10, Bitmap.Black);
PPM.Create("testpic.ppm", testpic);
END Main.
[edit] OCaml
let raster_circle ~img ~color ~c:(x0, y0) ~r =
let plot = put_pixel img color in
let x = 0
and y = r
and m = 5 - 4 * r
in
let rec loop x y m =
plot (x0 + x) (y0 + y);
plot (x0 + y) (y0 + x);
plot (x0 - x) (y0 + y);
plot (x0 - y) (y0 + x);
plot (x0 + x) (y0 - y);
plot (x0 + y) (y0 - x);
plot (x0 - x) (y0 - y);
plot (x0 - y) (y0 - x);
let y, m =
if m > 0
then (y - 1), (m - 8 * y)
else y, m
in
if x <= y then
let x = x + 1 in
let m = m + 8 * x + 4 in
loop x y m
in
loop x y m
;;
[edit] PL/I
/* Plot three circles. */
CIRCLE: PROCEDURE OPTIONS (MAIN);
declare image (-20:20, -20:20) character (1);
declare j fixed binary;
image = '.';
image(0,*) = '-';
image(*,0) = '|';
image(0,0) = '+';
CALL DRAW_CIRCLE (0, 0, 11);
CALL DRAW_CIRCLE (0, 0, 8);
CALL DRAW_CIRCLE (0, 0, 19);
do j = hbound(image,1) to lbound(image,1) by -1;
put skip edit (image(j,*)) (a(1));
end;
draw_circle: procedure (x0, y0, radius); /* 14 May 2010. */
declare ( x0, y0, radius ) fixed binary;
declare ( ddfx, ddfy, x, y, f ) fixed binary;
declare debug bit (1) aligned static initial ('0'b);
f = 1-radius;
ddfx = 1;
ddfy = -2*radius;
x = 0;
y = radius;
image(x0, y0+radius) = '*'; /* Octet 0. */
image(x0+radius, y0) = '*'; /* Octet 1. */
image(x0, y0-radius) = '*'; /* Octet 2. */
image(x0-radius, y0) = '*'; /* Octet 3. */
do while (x < y);
if f >= 0 then
do; y = y - 1; ddfy = ddfy +2; f = f + ddfy; end;
x = x + 1;
ddfx = ddfx + 2;
f = f + ddfx;
image(x0+x, y0+y) = '0'; /* Draws octant 0. */
image(x0+y, y0+x) = '1'; /* Draws octant 1. */
image(x0+y, y0-x) = '2'; /* Draws octant 2. */
image(x0+x, y0-y) = '3'; /* Draws octant 3. */
image(x0-x, y0-y) = '4'; /* Draws octant 4. */
image(x0-y, y0-x) = '5'; /* Draws octant 5. */
image(x0-y, y0+x) = '6'; /* Draws octant 6. */
image(x0-x, y0+y) = '7'; /* Draws octant 7. */
end;
end draw_circle;
END CIRCLE;
Output for three circles centered at the origin.
....................|....................
................2222*1111................
.............222....|....111.............
...........22.......|.......11...........
..........2.........|.........1..........
........22..........|..........11........
.......3............|............0.......
......2.............|.............1......
.....3..............|..............0.....
.....3...........222*111...........0.....
....3..........22...|...11..........0....
...3..........2.....|.....1..........0...
...3........32....22*11....11........0...
..3.........3...22..|..11...0.........0..
..3........3...3....|....0...0........0..
..3.......3...2.....|.....1...0.......0..
.3........3..3......|......0..0........0.
.3.......3...3......|......0...0.......0.
.3.......3..3.......|.......0..0.......0.
.3.......3..3.......|.......0..0.......0.
-*-------*--*-------+-------*--*-------*-
.4.......4..4.......|.......7..7.......7.
.4.......4..4.......|.......7..7.......7.
.4.......4...4......|......7...7.......7.
.4........4..4......|......7..7........7.
..4.......4...5.....|.....6...7.......7..
..4........4...4....|....7...7........7..
..4.........4...55..|..66...7.........7..
...4........55....55*66....67........7...
...4..........5.....|.....6..........7...
....4..........55...|...66..........7....
.....4...........555*666...........7.....
.....4..............|..............7.....
......5.............|.............6......
.......4............|............7.......
........55..........|..........66........
..........5.........|.........6..........
...........55.......|.......66...........
.............555....|....666.............
................5555*6666................
....................|....................
[edit] PicoLisp
(de midPtCircle (Img CX CY Rad)
(let (F (- 1 Rad) DdFx 0 DdFy (* -2 Rad) X 0 Y Rad)
(set (nth Img (+ CY Rad) CX) 1)
(set (nth Img (- CY Rad) CX) 1)
(set (nth Img CY (+ CX Rad)) 1)
(set (nth Img CY (- CX Rad)) 1)
(while (> Y X)
(when (ge0 F)
(dec 'Y)
(inc 'F (inc 'DdFy 2)) )
(inc 'X)
(inc 'F (inc (inc 'DdFx 2)))
(set (nth Img (+ CY Y) (+ CX X)) 1)
(set (nth Img (+ CY Y) (- CX X)) 1)
(set (nth Img (- CY Y) (+ CX X)) 1)
(set (nth Img (- CY Y) (- CX X)) 1)
(set (nth Img (+ CY X) (+ CX Y)) 1)
(set (nth Img (+ CY X) (- CX Y)) 1)
(set (nth Img (- CY X) (+ CX Y)) 1)
(set (nth Img (- CY X) (- CX Y)) 1) ) ) )
(let Img (make (do 120 (link (need 120 NIL 0)))) # Create image 120 x 120
(midPtCircle Img 60 60 50) # Draw circle
(out "img.pbm" # Write to bitmap file
(prinl "P1")
(prinl 120 " " 120)
(mapc prinl Img) ) )
[edit] PureBasic
Procedure rasterCircle(cx, cy, r, Color)
;circle must lie completely within the image boundaries
Protected f= 1 - r
Protected ddF_X, ddF_Y = -2 * r
Protected x, y = r
Plot(cx, cy + r, Color)
Plot(cx, cy - r, Color)
Plot(cx + r, cy, Color)
Plot(cx - r, cy, Color)
While x < y
If f >= 0
y - 1
ddF_Y + 2
f + ddF_Y
EndIf
x + 1
ddF_X + 2
f + ddF_X + 1
Plot(cx + x, cy + y, Color)
Plot(cx - x, cy + y, Color)
Plot(cx + x, cy - y, Color)
Plot(cx - x, cy - y, Color)
Plot(cx + y, cy + x, Color)
Plot(cx - y, cy + x, Color)
Plot(cx + y, cy - x, Color)
Plot(cx - y, cy - x, Color)
Wend
EndProcedure
OpenWindow(0, 0, 0, 100, 100, "MidPoint Circle Algorithm", #PB_Window_SystemMenu)
CreateImage(0, 100, 100, 32)
StartDrawing(ImageOutput(0))
Box(0, 0, 100, 100, RGB(0, 0, 0))
rasterCircle(25, 25, 20, RGB(255, 255, 255))
rasterCircle(50, 50, 40, RGB(255, 0, 0))
StopDrawing()
ImageGadget(0, 0, 0, 0, 0, ImageID(0))
Repeat: Until WaitWindowEvent() = #PB_Event_CloseWindow
[edit] Python
Works with: Python version 3.1
Extending the example given here
def circle(self, x0, y0, radius, colour=black):
f = 1 - radius
ddf_x = 1
ddf_y = -2 * radius
x = 0
y = radius
self.set(x0, y0 + radius, colour)
self.set(x0, y0 - radius, colour)
self.set(x0 + radius, y0, colour)
self.set(x0 - radius, y0, colour)
while x < y:
if f >= 0:
y -= 1
ddf_y += 2
f += ddf_y
x += 1
ddf_x += 2
f += ddf_x
self.set(x0 + x, y0 + y, colour)
self.set(x0 - x, y0 + y, colour)
self.set(x0 + x, y0 - y, colour)
self.set(x0 - x, y0 - y, colour)
self.set(x0 + y, y0 + x, colour)
self.set(x0 - y, y0 + x, colour)
self.set(x0 + y, y0 - x, colour)
self.set(x0 - y, y0 - x, colour)
Bitmap.circle = circle
bitmap = Bitmap(25,25)
bitmap.circle(x0=12, y0=12, radius=12)
bitmap.chardisplay()
'''
The origin, 0,0; is the lower left, with x increasing to the right,
and Y increasing upwards.
The program above produces the following display :
+-------------------------+
| @@@@@@@ |
| @@ @@ |
| @@ @@ |
| @ @ |
| @ @ |
| @ @ |
| @ @ |
| @ @ |
| @ @ |
|@ @|
|@ @|
|@ @|
|@ @|
|@ @|
|@ @|
|@ @|
| @ @ |
| @ @ |
| @ @ |
| @ @ |
| @ @ |
| @ @ |
| @@ @@ |
| @@ @@ |
| @@@@@@@ |
+-------------------------+
'''
[edit] Ruby
Pixel = Struct.new(:x, :y)
class Pixmap
def draw_circle(pixel, radius, colour)
validate_pixel(pixel.x, pixel.y)
self[pixel.x, pixel.y + radius] = colour
self[pixel.x, pixel.y - radius] = colour
self[pixel.x + radius, pixel.y] = colour
self[pixel.x - radius, pixel.y] = colour
f = 1 - radius
ddF_x = 1
ddF_y = -2 * radius
x = 0
y = radius
while x < y
if f >= 0
y -= 1
ddF_y += 2
f += ddF_y
end
x += 1
ddF_x += 2
f += ddF_x
self[pixel.x + x, pixel.y + y] = colour
self[pixel.x + x, pixel.y - y] = colour
self[pixel.x - x, pixel.y + y] = colour
self[pixel.x - x, pixel.y - y] = colour
self[pixel.x + y, pixel.y + x] = colour
self[pixel.x + y, pixel.y - x] = colour
self[pixel.x - y, pixel.y + x] = colour
self[pixel.x - y, pixel.y - x] = colour
end
end
end
bitmap = Pixmap.new(30, 30)
bitmap.draw_circle(Pixel[14,14], 12, RGBColour::BLACK)
[edit] Tcl
Library: Tk ref Basic bitmap storage#Tcl and Assertions#Tcl
package require Tcl 8.5
package require Tk
proc drawCircle {image colour point radius} {
lassign $point x0 y0
setPixel $image $colour [list $x0 [expr {$y0 + $radius}]]
setPixel $image $colour [list $x0 [expr {$y0 - $radius}]]
setPixel $image $colour [list [expr {$x0 + $radius}] $y0]
setPixel $image $colour [list [expr {$x0 - $radius}] $y0]
set f [expr {1 - $radius}]
set ddF_x 1
set ddF_y [expr {-2 * $radius}]
set x 0
set y $radius
while {$x < $y} {
assert {$ddF_x == 2 * $x + 1}
assert {$ddF_y == -2 * $y}
assert {$f == $x*$x + $y*$y - $radius*$radius + 2*$x - $y + 1}
if {$f >= 0} {
incr y -1
incr ddF_y 2
incr f $ddF_y
}
incr x
incr ddF_x 2
incr f $ddF_x
setPixel $image $colour [list [expr {$x0 + $x}] [expr {$y0 + $y}]]
setPixel $image $colour [list [expr {$x0 - $x}] [expr {$y0 + $y}]]
setPixel $image $colour [list [expr {$x0 + $x}] [expr {$y0 - $y}]]
setPixel $image $colour [list [expr {$x0 - $x}] [expr {$y0 - $y}]]
setPixel $image $colour [list [expr {$x0 + $y}] [expr {$y0 + $x}]]
setPixel $image $colour [list [expr {$x0 - $y}] [expr {$y0 + $x}]]
setPixel $image $colour [list [expr {$x0 + $y}] [expr {$y0 - $x}]]
setPixel $image $colour [list [expr {$x0 - $y}] [expr {$y0 - $x}]]
}
}
# create the image and display it
set img [newImage 200 100]
label .l -image $img
pack .l
fill $img black
drawCircle $img blue {100 50} 49
[edit] Vedit macro language
// Draw a circle using Bresenham's circle algorithm.
// #21 = center x, #22 = center y; #23 = radius
:DRAW_CIRCLE:
#30 = 1 - #23 // f
#31 = 0 // ddF_x
#32 = -2 * #23 // ddF_y
#41 = 0 // x
#42 = #23 // y
while (#41 <= #42) {
#1 = #21+#41; #2 = #22+#42; Call("DRAW_PIXEL")
#1 = #21-#41; #2 = #22+#42; Call("DRAW_PIXEL")
#1 = #21+#41; #2 = #22-#42; Call("DRAW_PIXEL")
#1 = #21-#41; #2 = #22-#42; Call("DRAW_PIXEL")
#1 = #21+#42; #2 = #22+#41; Call("DRAW_PIXEL")
#1 = #21-#42; #2 = #22+#41; Call("DRAW_PIXEL")
#1 = #21+#42; #2 = #22-#41; Call("DRAW_PIXEL")
#1 = #21-#42; #2 = #22-#41; Call("DRAW_PIXEL")
if (#30 >= 0) {
#42--
#32 += 2
#30 += #32
}
#41++
#31 += 2
#30 += #31 + 1
}
return
Categories: Programming Tasks | Raster graphics operations | Ada | ALGOL 68 | C | Common Lisp | Forth | Fortran | Haskell | J | Modula-3 | OCaml | PL/I | PicoLisp | PureBasic | Python | Ruby | Tcl | Tk | Vedit macro language
