40 lines
838 B
Text
40 lines
838 B
Text
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#version 330 core
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uniform sampler2D lum_tex;
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uniform float exposure_compensation;
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const float one_over_log10 = 1.0 / log(10.0);
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float log10(float x)
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{
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return one_over_log10 * log(x);
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}
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/*
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* Exposure curve from 'Perceptual Effects in Real-time Tone Mapping'.
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* http://resources.mpi-inf.mpg.de/hdr/peffects/krawczyk05sccg.pdf
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*/
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float key_value(float L)
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{
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return 1.0 - 2.0 / (log10(L + 1.0) + 2.0);
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}
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float get_exposure()
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{
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float avg_lum = max(texelFetch(lum_tex, ivec2(0), 0).r, 0.001);
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float linear_exposure = key_value(avg_lum) / avg_lum;
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float exposure = log2(max(linear_exposure, 0.0001));
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exposure += exposure_compensation;
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return exposure;
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}
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vec3 apply_exposure(vec3 color)
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{
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return color * exp2(get_exposure());
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}
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vec3 undo_exposure(vec3 color)
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{
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return color / exp2(get_exposure());
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}
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