63 lines
1.5 KiB
Plaintext
63 lines
1.5 KiB
Plaintext
func hitf(sph, x, y) {
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x -= sph[0]
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y -= sph[1]
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var z = (sph[3]**2 - (x**2 + y**2))
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z < 0 && return nil
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z.sqrt!
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[sph[2] - z, sph[2] + z]
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}
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func normalize(v) {
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v / v.abs
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}
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func dot(x, y) {
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max(0, x*y)
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}
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var pos = [120, 120, 0, 120]
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var neg = [-77, -33, -100, 190]
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var light = normalize(Vector(-12, 13, -10))
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func draw(k, amb) {
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STDOUT.binmode(':raw')
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print ("P5\n", pos[0]*2 + 3, " ", pos[1]*2 + 3, "\n255\n")
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for y in ((pos[1] - pos[3] - 1) .. (pos[1] + pos[3] + 1)) {
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var row = []
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for x in ((pos[0] - pos[3] - 1) .. (pos[0] + pos[3] + 1)) {
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var hit = 0
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var hs = []
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var h = hitf(pos, x, y)
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if (!h) { hit = 0; h = [0, 0] }
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elsif (!(hs = hitf(neg, x, y))) { hit = 1; hs = [0, 0] }
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elsif (hs[0] > h[0]) { hit = 1 }
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elsif (hs[1] > h[0]) { hit = (hs[1] > h[1] ? 0 : 2) }
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else { hit = 1 }
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var (val, v)
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given(hit) {
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when (0) { val = 0}
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when (1) { v = Vector(x-pos[0], y-pos[1], h[0]-pos[2]) }
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default { v = Vector(neg[0]-x, neg[1]-y, neg[2]-hs[1]) }
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}
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if (defined(v)) {
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v = normalize(v)
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val = int((dot(v, light)**k + amb) * 255)
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val = (val > 255 ? 255 : (val < 0 ? 0 : val))
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}
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row.append(val)
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}
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print 'C*'.pack(row...)
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}
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}
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draw(2, 0.2)
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