132 lines
2.8 KiB
Bash
132 lines
2.8 KiB
Bash
/*
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* Copyright 2011-2022 Branimir Karadzic. All rights reserved.
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* License: https://github.com/bkaradzic/bgfx/blob/master/LICENSE
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*/
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#include <bgfx_shader.sh>
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uniform vec4 u_params0;
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#define u_textureLod u_params0.x
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#define u_textureLayer u_params0.y
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#define u_inLinear u_params0.z
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#define u_ev u_params0.w
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uniform vec4 u_params1;
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#define u_outputFormat u_params1.x
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#define u_sdrWhiteNits u_params1.y
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vec3 toLinear(vec3 _rgb)
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{
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return pow(abs(_rgb), vec3_splat(2.2) );
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}
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vec3 toGamma(vec3 _rgb)
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{
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return pow(abs(_rgb), vec3_splat(1.0/2.2) );
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}
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vec3 applyExposure(vec3 _rgb)
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{
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vec3 rgb = mix(toLinear(_rgb.xyz), _rgb.xyz, u_inLinear);
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return (rgb * pow(2.0, u_ev) );
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}
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vec4 toEv(vec4 _color)
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{
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return vec4(toGamma(applyExposure(_color.xyz) ), _color.w);
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}
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float toSrgbGamma(float _val)
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{
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if (_val <= 0.0031308)
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{
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return 12.92 * _val;
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}
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else
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{
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return 1.055 * pow(_val, (1.0/2.4) ) - 0.055;
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}
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}
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vec3 toSrgbGamma(vec3 _rgb)
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{
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_rgb.x = toSrgbGamma(_rgb.x);
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_rgb.y = toSrgbGamma(_rgb.y);
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_rgb.z = toSrgbGamma(_rgb.z);
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return _rgb;
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}
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vec3 toXyzFromSrgb(vec3 _rgb)
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{
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mat3 toXYZ = mat3(
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0.4125564, 0.3575761, 0.1804375,
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0.2126729, 0.7151522, 0.0721750,
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0.0193339, 0.1191920, 0.9503041
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);
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return mul(toXYZ, _rgb);
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}
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vec3 toRec2020FromXyz(vec3 _xyz)
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{
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mat3 toRec2020 = mat3(
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1.7166512, -0.3556708, -0.2533663,
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-0.6666844, 1.6164812, 0.0157685,
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0.0176399, -0.0427706, 0.9421031
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);
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return mul(toRec2020, _xyz);
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}
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vec3 toPqOetf(vec3 _color)
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{
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// reference PQ OETF will yield reference OOTF when
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// displayed on a reference monitor employing EOTF
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float m1 = 0.1593017578125;
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float m2 = 78.84375;
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float c1 = 0.8359375;
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float c2 = 18.8515625;
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float c3 = 18.6875;
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vec3 Ym1 = pow(_color.xyz * (1.0/10000.0), vec3_splat(m1) );
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_color = pow((c1 + c2*Ym1) / (vec3_splat(1.0) + c3*Ym1), vec3_splat(m2) );
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return _color;
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}
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vec4 toOutput(vec4 _color, float _outputFormat, float _sdrWhiteNits)
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{
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// assumed that _color is linear with sRGB/rec709 primaries
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// and 1.0 is SDR white point
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vec3 outColor = vec3_splat(0.0);
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if (_outputFormat < 0.5)
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{
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// output == 0 -> sRGB/rec709, apply gamma
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// values over 1.0 will saturate
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outColor = toSrgbGamma(saturate(_color.xyz));
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}
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else if (_outputFormat < 1.5)
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{
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// output == 1 -> scRGB, remains linear.
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// values over 1.0 will appear as HDR
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outColor = _color.xyz;
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}
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else if (_outputFormat < 2.5)
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{
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// output == 2 -> PQ
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// change primaries from sRGB/rec709 to rec2020
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vec3 _xyz = toXyzFromSrgb(_color.xyz);
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outColor = toRec2020FromXyz(_xyz);
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// if 1.0 is SDR white, should map to 80 nits
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// but that could lead to dim results as SDR
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// monitors tend to be brighter than standard
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outColor = toPqOetf(outColor * _sdrWhiteNits);
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}
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return vec4(outColor, _color.w);
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}
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