-- Picture scene: Amigaball (by Richard Fhager, code adopted from Evalion)

w = 256
h = 256

setpicturesize(w,h)


-- Set Amiga Palette

colors = {}

for c = 0, 63, 1 do
 colors[c+1] = {c*4,0,0}
end

for c = 0, 63, 1 do
 colors[c+65] = {255,c*4,c*4}
end

for c = 0, 63, 1 do
 colors[c+129] = {255-c*4,255-c*4,255-c*4}
end

for c = 1, #colors, 1 do
 setcolor(c-1,colors[c][1],colors[c][2],colors[c][3]) 
end


-- Make Amiga ball

for y = 0, h - 1, 1 do
  for x = 0, w - 1, 1 do

   -- Fractionalize image dimensions
   ox = x / w;
   oy = y / h;

   -- Ball
   Xr = ox-0.5; Yr = oy-0.5; 
   W = (1 - 2*math.sqrt(Xr*Xr + Yr*Yr)); 

   -- 'FishEye' distortion / Fake 3D
   F = (math.cos((ox-0.5)*math.pi)*math.cos((oy-0.5)*math.pi))*0.65;
   ox = ox - (ox-0.5)*F; 
   oy = oy - (oy-0.5)*F; 

   -- Checkers
   V = ((math.floor(0.25+ox*10)+math.floor(1+oy*10)) % 2) * 255 * W;

   -- Specularities
   SPEC1 = math.max(0,(1-5*math.sqrt((ox-0.45)*(ox-0.45)+(oy-0.45)*(oy-0.45)))*112);
   SPEC2 = math.max(0,(1-15*math.sqrt((ox-0.49)*(ox-0.49)+(oy-0.48)*(oy-0.48)))*255);

   r = W * 255 + SPEC1 + SPEC2
   g = V + SPEC1 + SPEC2
   b = V + SPEC1 + SPEC2

   c = matchcolor(math.max(0,math.min(255,r)),math.max(0,math.min(255,g)),math.max(0,math.min(255,b)))
 
   putpicturepixel(x, y, c);

  end
end