aaquads_count.glsl

 
#version 430
 
#ifdef COMPUTE_SHADER
 
layout(binding= 0, r32ui) writeonly uniform uimage2D counters;  // 1024*1024
layout(binding= 1, r32ui) readonly uniform uimage2D primitives; // 8192*8192
 
shared uint group_primitives[64];
shared uint count;
 
layout(local_size_x= 8, local_size_y= 8) in;
void main( )
{
    if(gl_LocalInvocationIndex == 0)
        count= 0;
    uint local_primitive= uint( imageLoad(primitives, ivec2(gl_GlobalInvocationID)) );
    group_primitives[gl_LocalInvocationIndex]= local_primitive;
    barrier();
    
    // compter le nombre de triangles dans un bloc 8x8 de pixels / 1 groupe de threads
    // beurk o(n*n)...
    for(int i= 0; i < 64; i++)
    {
        uint primitive= group_primitives[i];
        if(gl_LocalInvocationIndex == 0 && primitive > 0)
            count++;
        
        if(local_primitive == primitive)
            group_primitives[gl_LocalInvocationIndex]= 0;
        barrier();
    }
    
    if(gl_LocalInvocationIndex == 0)
        imageStore(counters, ivec2(gl_WorkGroupID), uvec4( count ));
}
#endif