demos/forestpond/data/water_variance_x.glsl

   1 #pragma MSP stage(compute)
   2 layout(local_size_x=8, local_size_y=8) in;
   3
   4 uniform sampler2D surface_in;
   5 uniform sampler2D bottom_in;
   6 uniform sampler2D normals_in;
   7 layout(r16f) uniform image2D variance_out;
   8
   9 void main()
  10 {
  11         ivec2 coord = ivec2(gl_GlobalInvocationID.xy)+ivec2(4, 1);
  12         float variance = 0.0;
  13         for(int i=-3; i<=3; ++i)
  14         {
  15                 ivec2 c = coord+ivec2(i, 0);
  16                 float depth = texelFetch(surface_in, c, 0).x-texelFetch(bottom_in, c, 0).x;
  17                 vec2 normal_xy = texelFetch(normals_in, c, 0).xy*2.0-1.0;
  18                 float xy_sq = dot(normal_xy, normal_xy);
  19                 float slope_sq = xy_sq/max(1-xy_sq, 0.001);
  20                 variance += slope_sq*clamp(depth, 0.0, 1.0);
  21         }
  22         imageStore(variance_out, coord, vec4(variance/7.0, 0.0, 0.0, 0.0));
  23 }