45 lines
1.4 KiB
Text
45 lines
1.4 KiB
Text
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#include "common.nocompile.glsl"
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layout(local_size_x = 256, local_size_y = 1) in;
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layout(r16f, binding = 0) uniform image2D target_image;
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// adapated from https://bruop.github.io/exposure/ and http://www.alextardif.com/HistogramLuminance.html
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shared uint histogram_shared[256];
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layout(std430, binding = 1) buffer HistogramBuffer {
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uint histogram[];
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};
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layout(push_constant, binding = 2) uniform readonly PushConstant{
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vec4 params;
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};
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void main() {
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uint count_for_this_bin = histogram[gl_LocalInvocationIndex];
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histogram_shared[gl_LocalInvocationIndex] = count_for_this_bin * gl_LocalInvocationIndex;
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groupMemoryBarrier();
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histogram[gl_LocalInvocationIndex] = 0;
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for(uint cutoff = (256 >> 1); cutoff > 0; cutoff >>= 1) {
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if(uint(gl_LocalInvocationIndex) < cutoff) {
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histogram_shared[gl_LocalInvocationIndex] += histogram_shared[gl_LocalInvocationIndex + cutoff];
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}
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groupMemoryBarrier();
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}
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if(gl_LocalInvocationIndex == 0) {
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float weightedLogAverage = (histogram_shared[0] / max(params.w - float(count_for_this_bin), 1.0)) - 1.0;
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float weightedAvgLum = exp2(weightedLogAverage / 254.0 * params.y + params.x);
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float lumLastFrame = imageLoad(target_image, ivec2(0, 0)).x;
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float adaptedLum = lumLastFrame + (weightedAvgLum - lumLastFrame) * params.z;
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imageStore(target_image, ivec2(0, 0), vec4(adaptedLum, 0.0, 0.0, 0.0));
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}
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}
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