private AccelerationStructureBuffers CreateBottomLevelAS(ID3D12Device5 pDevice, ID3D12GraphicsCommandList4 pCmdList, ID3D12Resource vb, uint vbCount, ID3D12Resource ib, uint ibCount)
{
int geometryCount = 1;
RaytracingGeometryDescription[] geomDesc = new RaytracingGeometryDescription[geometryCount];
// Primitives
geomDesc[0].Type = RaytracingGeometryType.Triangles;
geomDesc[0].Triangles = new RaytracingGeometryTrianglesDescription();
geomDesc[0].Triangles.VertexBuffer = new GpuVirtualAddressAndStride();
geomDesc[0].Triangles.VertexBuffer.StartAddress = vb.GPUVirtualAddress;
geomDesc[0].Triangles.VertexBuffer.StrideInBytes = Unsafe.SizeOf <VertexPositionNormalTangentTexture>();
geomDesc[0].Triangles.VertexFormat = Format.R32G32B32_Float;
geomDesc[0].Triangles.VertexCount = (int)vbCount;
geomDesc[0].Triangles.IndexBuffer = ib.GPUVirtualAddress;
geomDesc[0].Triangles.IndexCount = (int)ibCount;
geomDesc[0].Triangles.IndexFormat = Format.R16_UInt;
geomDesc[0].Flags = RaytracingGeometryFlags.Opaque;
// Get the size requirements for the scratch and AS buffers
BuildRaytracingAccelerationStructureInputs inputs = new BuildRaytracingAccelerationStructureInputs();
inputs.Layout = ElementsLayout.Array;
inputs.Flags = RaytracingAccelerationStructureBuildFlags.None;
inputs.DescriptorsCount = geometryCount;
inputs.GeometryDescriptions = geomDesc;
inputs.Type = RaytracingAccelerationStructureType.BottomLevel;
RaytracingAccelerationStructurePrebuildInfo info;
info = pDevice.GetRaytracingAccelerationStructurePrebuildInfo(inputs);
// Create the buffers. They need to support UAV, and since we are going to immediately use them, we create them with an unordered-access state
AccelerationStructureBuffers buffers = new AccelerationStructureBuffers();
buffers.pScratch = this.CreateBuffer(pDevice, (uint)info.ScratchDataSizeInBytes, ResourceFlags.AllowUnorderedAccess, ResourceStates.UnorderedAccess, kDefaultHeapProps);
buffers.pResult = this.CreateBuffer(pDevice, (uint)info.ResultDataMaxSizeInBytes, ResourceFlags.AllowUnorderedAccess, ResourceStates.RaytracingAccelerationStructure, kDefaultHeapProps);
// Create the bottom-level AS
BuildRaytracingAccelerationStructureDescription asDesc = new BuildRaytracingAccelerationStructureDescription();
asDesc.Inputs = inputs;
asDesc.DestinationAccelerationStructureData = buffers.pResult.GPUVirtualAddress;
asDesc.ScratchAccelerationStructureData = buffers.pScratch.GPUVirtualAddress;
pCmdList.BuildRaytracingAccelerationStructure(asDesc);
// We need to insert a UAV barrier before using the acceleration structures in a raytracing operation
ResourceBarrier uavBarrier = new ResourceBarrier(new ResourceUnorderedAccessViewBarrier(buffers.pResult));
pCmdList.ResourceBarrier(uavBarrier);
return(buffers);
}
private AccelerationStructureBuffers CreateBottomLevelAS(ID3D12Device5 device, ID3D12GraphicsCommandList4 commandList,
ID3D12Resource[] vertexBuffers, int[] vertexCounts, int geometryCount)
{
RaytracingGeometryDescription[] descs = new RaytracingGeometryDescription[geometryCount];
for (int i = 0; i < descs.Length; i++)
{
descs[i] = new RaytracingGeometryDescription();
descs[i].Type = RaytracingGeometryType.Triangles;
descs[i].Triangles = new RaytracingGeometryTrianglesDescription();
descs[i].Triangles.VertexBuffer = new GpuVirtualAddressAndStride();
descs[i].Triangles.VertexBuffer.StartAddress = vertexBuffers[i].GPUVirtualAddress;
descs[i].Triangles.VertexBuffer.StrideInBytes = 3 * 4;
descs[i].Triangles.VertexFormat = Format.R32G32B32_Float;
descs[i].Triangles.VertexCount = vertexCounts[i];
descs[i].Flags = RaytracingGeometryFlags.Opaque;
}
BuildRaytracingAccelerationStructureInputs inputs = new BuildRaytracingAccelerationStructureInputs();
inputs.Layout = ElementsLayout.Array;
inputs.Flags = RaytracingAccelerationStructureBuildFlags.None;
inputs.DescriptorsCount = geometryCount;
inputs.GeometryDescriptions = descs;
inputs.Type = RaytracingAccelerationStructureType.BottomLevel;
RaytracingAccelerationStructurePrebuildInfo info = device.GetRaytracingAccelerationStructurePrebuildInfo(inputs);
HeapProperties properties = new HeapProperties(HeapType.Default, CpuPageProperty.Unknown, MemoryPool.Unknown, 0, 0);
AccelerationStructureBuffers buffers = new AccelerationStructureBuffers();
buffers.Scratch = CreateBuffer(device, info.ScratchDataSizeInBytes, ResourceFlags.AllowUnorderedAccess, ResourceStates.UnorderedAccess, properties);
buffers.Result = CreateBuffer(device, info.ResultDataMaxSizeInBytes, ResourceFlags.AllowUnorderedAccess, ResourceStates.RaytracingAccelerationStructure, properties);
BuildRaytracingAccelerationStructureDescription asDesc = new BuildRaytracingAccelerationStructureDescription();
asDesc.Inputs = inputs;
asDesc.DestinationAccelerationStructureData = buffers.Result.GPUVirtualAddress;
asDesc.ScratchAccelerationStructureData = buffers.Scratch.GPUVirtualAddress;
commandList.BuildRaytracingAccelerationStructure(asDesc);
commandList.ResourceBarrier(ResourceBarrier.BarrierUnorderedAccessView(buffers.Result));
return(buffers);
}
