CodeWalker/Shaders/PPReduceTo1DCS.hlsl
2018-03-13 22:24:18 -04:00

64 lines
2.0 KiB
HLSL

Texture2D Input : register( t0 );
RWStructuredBuffer<float> Result : register( u0 );
cbuffer cbCS : register( b0 )
{
uint4 g_param; // (g_param.x, g_param.y) is the x and y dimensions of the Dispatch call
// (g_param.z, g_param.w) is the size of the above Input Texture2D
};
//#define CS_FULL_PIXEL_REDUCTION // Defining this or not must be the same as in PostProcessor....
#define blocksize 8
#define blocksizeY 8
#define groupthreads (blocksize*blocksizeY)
groupshared float accum[groupthreads];
static const float4 LUM_VECTOR = float4(.299, .587, .114, 0);
[numthreads(blocksize,blocksizeY,1)]
void main( uint3 Gid : SV_GroupID, uint3 DTid : SV_DispatchThreadID, uint3 GTid : SV_GroupThreadID, uint GI : SV_GroupIndex )
{
float4 s =
#ifdef CS_FULL_PIXEL_REDUCTION
Input.Load( uint3(DTid.xy , 0) )+
Input.Load( uint3(DTid.xy + uint2(blocksize*g_param.x, 0), 0) ) +
Input.Load( uint3(DTid.xy + uint2(0, blocksizeY*g_param.y), 0) ) +
Input.Load( uint3(DTid.xy + uint2(blocksize*g_param.x, blocksizeY*g_param.y), 0) );
#else
Input.Load( uint3((float)DTid.x/81.0f*g_param.z, (float)DTid.y/81.0f*g_param.w, 0) );
#endif
accum[GI] = dot( s, LUM_VECTOR );
// Parallel reduction algorithm follows
GroupMemoryBarrierWithGroupSync();
if ( GI < 32 )
accum[GI] += accum[32+GI];
GroupMemoryBarrierWithGroupSync();
if ( GI < 16 )
accum[GI] += accum[16+GI];
GroupMemoryBarrierWithGroupSync();
if ( GI < 8 )
accum[GI] += accum[8+GI];
GroupMemoryBarrierWithGroupSync();
if ( GI < 4 )
accum[GI] += accum[4+GI];
GroupMemoryBarrierWithGroupSync();
if ( GI < 2 )
accum[GI] += accum[2+GI];
GroupMemoryBarrierWithGroupSync();
if ( GI < 1 )
accum[GI] += accum[1+GI];
if ( GI == 0 )
{
Result[Gid.y*g_param.x+Gid.x] = accum[0];
}
}