37 lines
988 B
GLSL
37 lines
988 B
GLSL
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#version 330 core
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layout(location = 0) out uint fragHits;
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uniform sampler2D hdr_tex;
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// color.glsl
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float linear_srgb_to_luminance(vec3 color);
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// histogram.glsl
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uint luminance_to_bin_index(float luminance);
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// exposure.glsl
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vec3 undo_exposure(vec3 color);
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void main()
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{
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ivec2 hdr_tex_size = textureSize(hdr_tex, 0);
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int column = int(gl_FragCoord.x);
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uint target_bin = uint(gl_FragCoord.y); // [0, 255]
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uint hits = 0u;
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for (int row = 0; row < hdr_tex_size.y; ++row) {
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vec3 hdr_color = texelFetch(hdr_tex, ivec2(column, row), 0).rgb;
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hdr_color = undo_exposure(hdr_color);
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// sRGB to relative luminance
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float lum = linear_srgb_to_luminance(hdr_color);
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// Get the bin index corresponding to the given pixel luminance
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uint pixel_bin = luminance_to_bin_index(lum);
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// Check if this pixel should go in the bin
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if (pixel_bin == target_bin) {
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hits += 1u;
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}
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}
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fragHits = hits;
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}
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