33 lines
1018 B
Plaintext
33 lines
1018 B
Plaintext
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#define TAU 6.283185307179586476925286766559005768394338798750211641949
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#define PHI 1.618033988749894848204586834365638117720309179805762862135
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#define MAX_RESOLUTION 64
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extern int resolution;
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extern float sigma;
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extern float amplitudes[MAX_RESOLUTION];
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extern vec2 offsets[MAX_RESOLUTION];
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extern vec2 range_min, range_max;
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float cdf(float x) {
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return .5 + .5*sign(x)*sqrt(1.-exp(-4./TAU * x*x));
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}
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float noise2d(vec2 pos) {
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float noise = 0.;
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for (int i=0; i < resolution; i++) {
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float angle = mod(float(i)*PHI, 1.)*TAU;
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float u = pos.x*cos(angle) - pos.y*sin(angle);
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float v = pos.x*cos(angle+TAU/4.) - pos.y*sin(angle+TAU/4.);
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float a = amplitudes[i];
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noise += a*mix(cos(u/a + offsets[i].x), cos(v/a + offsets[i].y), .5);
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}
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return cdf(noise/sigma);
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}
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vec4 effect(vec4 color, Image texture, vec2 texture_coords, vec2 pixel_coords)
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{
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vec2 coords = mix(range_min,range_max,texture_coords);
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float n = noise2d(coords);
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return vec4(n,n,n,1.);
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}
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