49 lines
No EOL
1.6 KiB
HLSL
49 lines
No EOL
1.6 KiB
HLSL
#include "../color/palette/hue.hlsl"
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/*
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contributors: Paniq
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description: based on the picture in http://home.hiroshima-u.ac.jp/kin/publications/TVC01/examples.pdf
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use: <float3> iridescence(<float> angle, <float> thickness)
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examples:
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- https://raw.githubusercontent.com/patriciogonzalezvivo/lygia_examples/main/color_iridescence_map.frag
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*/
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#ifndef FNC_IRIDESCENCE
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#define FNC_IRIDESCENCE
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float3 iridescence(float cosA, float thickness) {
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// typically the dot product of normal with eye ray
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float NxV = cosA;
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// energy of spectral colors
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float lum = 0.05064;
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// basic energy of light
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float luma = 0.01070;
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// tint of the final color
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float3 tint = float3(0.7333, 0.89804, 0.94902);
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// float3 tint = float3(0.49639,0.78252,0.88723);
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// interference rate at minimum angle
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float interf0 = 2.4;
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// phase shift rate at minimum angle
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float phase0 = 1.0 / 2.8;
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// interference rate at maximum angle
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float interf1 = interf0 * 4.0 / 3.0;
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// phase shift rate at maximum angle
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float phase1 = phase0;
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// fresnel (most likely completely wrong)
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float f = (NxV) * (NxV);
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float interf = lerp(interf0, interf1, f);
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float phase = lerp(phase0, phase1, f);
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float dp = (NxV + 1.0) * 0.5;
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// film hue
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float3 filmhue = lerp(hue(thickness * interf0 + dp, thickness * phase0),
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hue(thickness * interf1 + 0.1 + dp, thickness * phase1),
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f);
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float3 film = filmhue * lum + float3(0.49639, 0.78252, 0.88723) * luma;
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return (film * 3.0 + pow(f, 12.0)) * tint;
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}
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#endif |