public void Scan(
ref ComputeBuffer cb_in, ref ComputeBuffer cb_out,
int dataSize, int recurseNum = 0
)
{
Profiler.BeginSample("BlellochSumScan");
int blellochGridSize = _gridSizes[recurseNum];
ComputeBuffer cb_sumScanBlockSum = cb_sumScanBlockSums[recurseNum];
ComputeShaderUtil.ZeroOut(ref cb_sumScanBlockSum, blellochGridSize);
// sum scan data allocated to each block
cs_blellochSumScan.SetInt(PropertyID.len, dataSize);
cs_blellochSumScan.SetBuffer(kn_preSumScan, BufferID.cb_out, cb_out);
cs_blellochSumScan.SetBuffer(kn_preSumScan, BufferID.cb_in, cb_in);
cs_blellochSumScan.SetBuffer(kn_preSumScan, BufferID.cb_blockSums, cb_sumScanBlockSum);
cs_blellochSumScan.Dispatch(kn_preSumScan, blellochGridSize, 1, 1);
// sum scan total sums produced by each block
// use basic implementation if number of total sums is <= 2 * Graphics.M_BLOCK_SZ
// (this requires only one block to do the scan)
if (blellochGridSize <= Graphics.S_BLOCK_SZ)
{
ComputeShaderUtil.ZeroOut(ref cb_dummyGrpSums, 1);
ComputeBuffer cb_preSumScanTemp = cb_preSumScanTemps[recurseNum];
ComputeShaderUtil.CopyBuffer(ref cb_sumScanBlockSum, ref cb_preSumScanTemp, blellochGridSize);
cs_blellochSumScan.SetInt(PropertyID.len, blellochGridSize);
cs_blellochSumScan.SetBuffer(kn_preSumScan, BufferID.cb_out, cb_sumScanBlockSum);
cs_blellochSumScan.SetBuffer(kn_preSumScan, BufferID.cb_in, cb_preSumScanTemp);
cs_blellochSumScan.SetBuffer(kn_preSumScan, BufferID.cb_blockSums, cb_dummyGrpSums);
cs_blellochSumScan.Dispatch(kn_preSumScan, 1, 1, 1);
}
else // else, recurse on this same function as you'll need the full-blown scan for the block sums
{
ComputeBuffer cb_inBlockSum = cb_inBlockSums[recurseNum];
ComputeShaderUtil.CopyBuffer(ref cb_sumScanBlockSum, ref cb_inBlockSum, blellochGridSize);
Scan(ref cb_inBlockSum, ref cb_sumScanBlockSum, blellochGridSize, recurseNum + 1);
}
ComputeBuffer cb_addBlockSumsTemp = cb_addBlockSumsTemps[recurseNum];
ComputeShaderUtil.CopyBuffer(ref cb_out, ref cb_addBlockSumsTemp, dataSize);
// add each block's total sum to its scan output in order to get the final, global scanned array
cs_blellochSumScan.SetInt(PropertyID.len, dataSize);
cs_blellochSumScan.SetBuffer(kn_addBlockSums, BufferID.cb_out, cb_out);
cs_blellochSumScan.SetBuffer(kn_addBlockSums, BufferID.cb_in, cb_addBlockSumsTemp);
cs_blellochSumScan.SetBuffer(kn_addBlockSums, BufferID.cb_blockSums, cb_sumScanBlockSum);
cs_blellochSumScan.Dispatch(kn_addBlockSums, blellochGridSize, 1, 1);
Profiler.EndSample();
}
public void Scan(ref ComputeBuffer cb_in)
{
Profiler.BeginSample("HillisSteeleSumScan");
cs_hillisSteeleSumScan.SetInt(PropertyID.len, _dataSize);
cs_hillisSteeleSumScan.SetBuffer(kn_hillisSteeleSumScan, BufferID.cb_in, cb_in);
cs_hillisSteeleSumScan.SetBuffer(kn_hillisSteeleSumScan, BufferID.cb_prev, cb_prev);
for (int offset = 1; offset < _dataSize; offset <<= 1)
{
ComputeShaderUtil.CopyBuffer(ref cb_in, ref cb_prev, _dataSize);
cs_hillisSteeleSumScan.SetInt(PropertyID.offset, offset);
cs_hillisSteeleSumScan.Dispatch(kn_hillisSteeleSumScan, _gridSize, 1, 1);
}
Profiler.EndSample();
}