// Generates an in-place depth pyramid
// TODO: Mip-mapping depth is problematic for precision at lower mips, generate a packed atlas instead
public void RenderMinDepthPyramid(CommandBuffer cmd, RenderTexture texture, HDUtils.PackedMipChainInfo info)
{
HDUtils.CheckRTCreated(texture);
var cs = m_DepthPyramidCS;
int kernel = m_DepthDownsampleKernel;
// TODO: Do it 1x MIP at a time for now. In the future, do 4x MIPs per pass, or even use a single pass.
// Note: Gather() doesn't take a LOD parameter and we cannot bind an SRV of a MIP level,
// and we don't support Min samplers either. So we are forced to perform 4x loads.
for (int i = 1; i < info.mipLevelCount; i++)
{
Vector2Int dstSize = info.mipLevelSizes[i];
Vector2Int dstOffset = info.mipLevelOffsets[i];
Vector2Int srcSize = info.mipLevelSizes[i - 1];
Vector2Int srcOffset = info.mipLevelOffsets[i - 1];
Vector2Int srcLimit = srcOffset + srcSize - Vector2Int.one;
m_SrcOffset[0] = srcOffset.x;
m_SrcOffset[1] = srcOffset.y;
m_SrcOffset[2] = srcLimit.x;
m_SrcOffset[3] = srcLimit.y;
m_DstOffset[0] = dstOffset.x;
m_DstOffset[1] = dstOffset.y;
m_DstOffset[2] = 0;
m_DstOffset[3] = 0;
cmd.SetComputeIntParams(cs, HDShaderIDs._SrcOffsetAndLimit, m_SrcOffset);
cmd.SetComputeIntParams(cs, HDShaderIDs._DstOffset, m_DstOffset);
cmd.SetComputeTextureParam(cs, kernel, HDShaderIDs._DepthMipChain, texture);
cmd.DispatchCompute(cs, kernel, HDUtils.DivRoundUp(dstSize.x, 8), HDUtils.DivRoundUp(dstSize.y, 8), 1);
}
}
