79 lines
1.5 KiB
Plaintext
79 lines
1.5 KiB
Plaintext
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mat2 mkrot(in float t)
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{
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float s = sin(t);
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float c = cos(t);
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return mat2(c,-s,s,c);
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}
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void rotCam(inout vec3 ro, inout vec3 rd)
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{
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mat2 a = mkrot(.4);
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ro.yz *= a;
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rd.yz *= a;
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mat2 b = mkrot(iTime*.4);
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ro.xz *= b;
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rd.xz *= b;
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mat2 c = mkrot(sin(iTime*.4) * .5);
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ro.xy *= c;
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rd.xy *= c;
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}
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vec2 pom(in vec2 uv, in vec3 i)
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{
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float y = 0.0;
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float d = 2./256.;
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for (int k = 0; k < 512; k++)
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{
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float h = textureLod(iChannel0, uv, 2.5).r;
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if (abs(h - y) > 1.)
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break;
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y += i.y * d;
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uv += i.xz * d * 1e-1;
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}
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return uv;
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}
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vec3 pomNor(in vec2 uv)
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{
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const vec2 eps = vec2(1e-2,0);
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float t = textureLod(iChannel0, uv + eps.xy, 2.5).r;
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float b = textureLod(iChannel0, uv - eps.xy, 2.5).r;
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float l = textureLod(iChannel0, uv - eps.yx, 2.5).r;
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float r = textureLod(iChannel0, uv + eps.yx, 2.5).r;
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return normalize(vec3(r-l, 1e-1, b-t));
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}
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void mainImage( out vec4 fragColor, in vec2 fragCoord )
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{
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vec2 uv = (fragCoord-.5*iResolution.xy)/iResolution.y;
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vec3 s = normalize(vec3(1,1,0));
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vec3 ro = vec3(0,-.1,-1);
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vec3 rd = normalize(vec3(uv, 1));
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rotCam(ro, rd);
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vec3 col = vec3(0);
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float t = -ro.y/rd.y;
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vec3 p = ro + rd * t;
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vec3 ap = abs(p);
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if (t > 0. && max(max(ap.x,ap.y),ap.z) < .5)
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{
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vec2 st = pom(p.xz, rd);
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vec3 n = pomNor(st);
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col = texture(iChannel0, st).rgb * dot(n, s);
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}
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fragColor = vec4(col,1.0);
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}
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