Bitmap/Midpoint circle algorithm: Difference between revisions

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=={{header|zkl}}==
=={{header|zkl}}==
Image cribbed from the BBC BASIC entry. Algorithm from Wikipedia article.
Image cribbed from the BBC BASIC entry. Algorithm from Wikipedia article.<br/>
Uses the PPM class from http://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm#zkl
[[Image:circle_bbc.gif|right]]
[[Image:circle_bbc.gif|right]]
This is the code from the PPM class:
<lang zkl>class PPM{
fcn init(width,height,rgb=0){
<lang zkl> fcn circle(x0,y0,r,rgb){
sz:=width*height;
var [const]
data=sz.pump(Data(sz*3),T(Void,rgb.toBigEndian(3))), // initialize to Black (RGB=000)
w=width, h=height;
}
fcn fill(rgb){
sz:=data.len()/3;
data.clear(); sz.pump(data,T(Void,rgb.toBigEndian(3)));
}
fcn __sGet(x,y) { data.toBigEndian(3*y*w + 3*x,3); } //ppm[x,y]
fcn __sSet(rbg,x,y){ data[3*y*w + 3*x,3]=rbg.toBigEndian(3); } //ppm[x,y]=rgb
fcn write(out){
out.write("P6\n#rosettacode PPM\n%d %d\n255\n".fmt(w,h));
out.write(data);
}
fcn circle(x0,y0,r,rgb){
x:=r; y:=0; radiusError:=1-x;
x:=r; y:=0; radiusError:=1-x;
while(x >= y){
while(x >= y){
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else{ x-=1; radiusError+=2*(y - x + 1); }
else{ x-=1; radiusError+=2*(y - x + 1); }
}
}
}
}</lang>
}</lang>
<lang zkl>ppm:=PPM(200,200,0xFF|FF|FF);
<lang zkl>ppm:=PPM(200,200,0xFF|FF|FF);
ppm.circle(100,100,40,00); // black circle
ppm.circle(100,100,40,00); // black circle
Retrieved from "https://rosettacode.org/wiki/Bitmap/Midpoint_circle_algorithm"