25 lines
706 B
Text
25 lines
706 B
Text
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#version 330 core
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const float NUM_BINS = 254.0; // 256 - 2
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const float INV_NUM_BINS = 1.0 / NUM_BINS;
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const float MIN_LOG_LUM = -10.0;
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const float LOG_LUM_RANGE = 16.0;
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const float INV_LOG_LUM_RANGE = 1.0 / LOG_LUM_RANGE;
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uint luminance_to_bin_index(float luminance)
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{
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// Avoid taking the log of zero
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if (luminance < 0.005)
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return 0u;
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float log_lum = (log2(luminance) - MIN_LOG_LUM) * INV_LOG_LUM_RANGE;
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log_lum = clamp(log_lum, 0.0, 1.0);
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// From [0, 1] to [1, 255]. The 0th bin is handled by the near-zero check
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return uint(log_lum * NUM_BINS + 1.0);
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}
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float bin_index_to_luminance(float bin)
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{
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return exp2(((bin * INV_NUM_BINS) * LOG_LUM_RANGE) + MIN_LOG_LUM);
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}
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