1  #version 450 core
 2  
 3  layout (std140, binding = 0) uniform ratio_in
 4  {
 5      int ratio;
 6  };
 7  
 8  layout (set = 2, binding = 0) uniform usampler2D src;
 9  layout (set = 3, binding = 0) writeonly uniform uimage2D dst;
10  
11  layout (local_size_x = 32, local_size_y = 32, local_size_z = 1) in;
12  
13  void main()
14  {
15      uvec2 coords = gl_GlobalInvocationID.xy;
16      ivec2 imageSz = imageSize(dst);
17  
18      if (int(coords.x) >= imageSz.x || int(coords.y) >= imageSz.y)
19      {
20          return;
21      }
22  
23      uvec2 srcCoords = uvec2(coords.x << ratio, coords.y);
24  
25      uint r = texelFetchOffset(src, ivec2(srcCoords), 0, ivec2(0, 0)).r;
26      uint g = texelFetchOffset(src, ivec2(srcCoords), 0, ivec2(1, 0)).r;
27      uint b = texelFetchOffset(src, ivec2(srcCoords), 0, ivec2(2, 0)).r;
28      uint a = texelFetchOffset(src, ivec2(srcCoords), 0, ivec2(3, 0)).r;
29  
30      imageStore(dst, ivec2(coords), uvec4(r, g, b, a));
31  }