RWSTRUCTUREDBUFFER(counterBuffer, ParticleCounters, 4);
RWSTRUCTUREDBUFFER(indexBuffer, uint, 2);
RWSTRUCTUREDBUFFER(distanceBuffer, float, 6);

#define NumElements counterBuffer[0].aliveCount_afterSimulation

[numthreads(256, 1, 1)]
void main(uint3 Gid	: SV_GroupID,
	uint3 GTid : SV_GroupThreadID)
{
	uint4 tgp;

	tgp.x = Gid.x * 256;
	tgp.y = 0;
	tgp.z = NumElements;
	tgp.w = min(512, max(0, NumElements - Gid.x * 512));

	uint localID = tgp.x + GTid.x; // calculate threadID within this sortable-array

	uint index_low = localID & (job_params.x - 1);
	uint index_high = 2 * (localID - index_low);

	uint index = tgp.y + index_high + index_low;
	uint nSwapElem = tgp.y + index_high + job_params.y + job_params.z*index_low;

	if (nSwapElem<tgp.y + tgp.z)
	{
		float a = distanceBuffer[index];
		float b = distanceBuffer[nSwapElem];

		if (a > b)
		{
			distanceBuffer[index] = b;
			distanceBuffer[nSwapElem] = a;

			uint aI = indexBuffer[index];
			uint bI = indexBuffer[nSwapElem];
			indexBuffer[index] = bI;
			indexBuffer[nSwapElem] = aI;
		}
	}
}