1  #version 450 core
 2  
 3  layout (std140, binding = 0) uniform sample_counts_log2_in
 4  {
 5      ivec4 sample_counts_log2;
 6  };
 7  
 8  layout (set = 2, binding = 0) uniform usampler2D src;
 9  
10  layout (location = 0) out uvec4 colour;
11  
12  void main()
13  {
14      int deltaX = sample_counts_log2.x - sample_counts_log2.z;
15      int deltaY = sample_counts_log2.y - sample_counts_log2.w;
16      int samplesInXLog2 = sample_counts_log2.z;
17      int samplesInYLog2 = sample_counts_log2.w;
18      int samplesInX = 1 << samplesInXLog2;
19      int samplesInY = 1 << samplesInYLog2;
20  
21      int sampleIndex = gl_SampleID;
22  
23      int inX = (int(gl_FragCoord.x) << sample_counts_log2.x) | ((sampleIndex & (samplesInX - 1)) << deltaX);
24      int inY = (int(gl_FragCoord.y) << sample_counts_log2.y) | ((sampleIndex >> samplesInXLog2) << deltaY);
25  
26      colour = texelFetch(src, ivec2(inX, inY), 0);
27  }