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https://github.com/italicsjenga/slang-shaders.git
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30 lines
1 KiB
C
30 lines
1 KiB
C
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#ifndef LUT
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#define LUT
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// only #include in the fragment stage
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#pragma parameter LUT_Size1 "LUT Size 1" 16.0 1.0 64.0 1.0
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layout(set = 0, binding = 3) uniform sampler2D SamplerLUT1;
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// This shouldn't be necessary but it seems some undefined values can
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// creep in and each GPU vendor handles that differently. This keeps
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// all values within a safe range
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vec3 mixfix(vec3 a, vec3 b, float c)
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{
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return (a.z < 1.0) ? mix(a, b, c) : a;
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}
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vec3 lut1(vec3 in_col)
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{
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float red = ( in_col.r * (LUT_Size1 - 1.0) + 0.4999 ) / (LUT_Size1 * LUT_Size1);
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float green = ( in_col.g * (LUT_Size1 - 1.0) + 0.4999 ) / LUT_Size1;
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float blue1 = (floor( in_col.b * (LUT_Size1 - 1.0) ) / LUT_Size1) + red;
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float blue2 = (ceil( in_col.b * (LUT_Size1 - 1.0) ) / LUT_Size1) + red;
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float mixer = clamp(max((in_col.b - blue1) / (blue2 - blue1), 0.0), 0.0, 32.0);
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vec3 color1 = texture( SamplerLUT1, vec2( blue1, green )).rgb;
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vec3 color2 = texture( SamplerLUT1, vec2( blue2, green )).rgb;
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return mixfix(color1, color2, mixer);
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}
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#endif
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