Draw a sphere: Difference between revisions

=={{header|zkl}}==

Uses the PPM class from http://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm#zkl

{{trans|XPL0}}

<lang zkl>img:=PPM(640,480);

R:=100; R2:=R*R; //radius, in pixels; radius squared

X0:=640/2; Y0:=480/2; //coordinates of center of screen

foreach Y in ([-R..R]){ //for all the coordinates near the circle

foreach X in ([-R..R]){ // which is under the sphere

D2:=X*X + Y*Y;

C:=0; //default color is black

if(D2<=R2){ //coordinate is inside circle under sphere

Z:=(R2-D2).toFloat().sqrt();//height of point on surface of sphere above X,Y

C=0x82+Z-(X+Y)/2; //color is proportional; offset X and Y, and

} // shift color to upper limit of its range

img[X+X0,Y+Y0]=C.shiftLeft(8)+C; //green + blue = cyan

}

}

img.write(File("foo.ppm","wb"));</lang>

{{out}}See the XPL0 image.

The radius of 100 is the max before the color calculation overflows 24 bits so for a radius (R) of, say 200, use

<lang zkl>img[X+X0,Y+Y0]=C*140+C;</lang>