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https://github.com/italicsjenga/slang-shaders.git
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34 lines
1.4 KiB
C
34 lines
1.4 KiB
C
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#define kMaxNitsFor2084 10000.0f
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const mat3 k709_to_2020 = mat3 (
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0.6274040f, 0.3292820f, 0.0433136f,
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0.0690970f, 0.9195400f, 0.0113612f,
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0.0163916f, 0.0880132f, 0.8955950f);
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/* START Converted from (Copyright (c) Microsoft Corporation - Licensed under the MIT License.) https://github.com/microsoft/Xbox-ATG-Samples/tree/master/Kits/ATGTK/HDR */
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const mat3 kExpanded709_to_2020 = mat3 (
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0.6274040f, 0.3292820f, 0.0433136f,
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0.0457456f, 0.941777f, 0.0124772f,
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-0.00121055f, 0.0176041f, 0.983607f);
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const mat3 k2020Gamuts[2] = { k709_to_2020, kExpanded709_to_2020 };
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vec3 LinearToST2084(vec3 normalizedLinearValue)
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{
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vec3 ST2084 = pow((0.8359375f + 18.8515625f * pow(abs(normalizedLinearValue), vec3(0.1593017578f))) / (1.0f + 18.6875f * pow(abs(normalizedLinearValue), vec3(0.1593017578f))), vec3(78.84375f));
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return ST2084; /* Don't clamp between [0..1], so we can still perform operations on scene values higher than 10,000 nits */
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}
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/* END Converted from (Copyright (c) Microsoft Corporation - Licensed under the MIT License.) https://github.com/microsoft/Xbox-ATG-Samples/tree/master/Kits/ATGTK/HDR */
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/* Convert into HDR10 */
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vec3 Hdr10(vec3 hdr_linear, float paper_white_nits, float expand_gamut)
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{
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vec3 rec2020 = hdr_linear * k2020Gamuts[uint(expand_gamut)];
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vec3 linearColour = rec2020 * (paper_white_nits / kMaxNitsFor2084);
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vec3 hdr10 = LinearToST2084(linearColour);
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return hdr10;
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}
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