private void CreateAccelerationStructure()
{
vertexBuffers = new ID3D12Resource[2];
vertexBuffers[0] = CreateTriangle(device);
vertexBuffers[1] = CreatePlane(device);
var vertexCounts = new int[2];
vertexCounts[0] = 3;
vertexCounts[1] = 6;
AccelerationStructureBuffers[] bottomLevelBuffers = new AccelerationStructureBuffers[2];
bottomLevelBuffers[0] = CreateBottomLevelAS(device, commandList, vertexBuffers, vertexCounts, 2);
bottomLevelBuffers[1] = CreateBottomLevelAS(device, commandList, vertexBuffers, vertexCounts, 1);
bottomLevelAS = new ID3D12Resource[2];
bottomLevelAS[0] = bottomLevelBuffers[0].Result;
bottomLevelAS[1] = bottomLevelBuffers[1].Result;
CreateTopLevelAS(device, commandList, bottomLevelAS, ref tlasSize, false, 0);
SubmitCommandList();
fence.SetEventOnCompletion(fenceValue, fenceEvent);
fenceEvent.WaitOne();
var bufferIndex = swapChain.GetCurrentBackBufferIndex();
commandList.Reset(frameObjects[0].cmdAllocator, null);
topLevelAS = buffers.Result;
}
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);
}
private void CreateTopLevelAS(ID3D12Device5 device, ID3D12GraphicsCommandList4 commandList,
ID3D12Resource[] bottomLevelAS, ref long tlasSize, bool isUpdate, float rotate)
{
int instanceCount = 3;
BuildRaytracingAccelerationStructureInputs inputs = new BuildRaytracingAccelerationStructureInputs();
inputs.Layout = ElementsLayout.Array;
inputs.Flags = RaytracingAccelerationStructureBuildFlags.AllowUpdate;
inputs.DescriptorsCount = instanceCount;
inputs.Type = RaytracingAccelerationStructureType.TopLevel;
var info = device.GetRaytracingAccelerationStructurePrebuildInfo(inputs);
if (isUpdate == false)
{
HeapProperties properties = new HeapProperties(HeapType.Default, CpuPageProperty.Unknown, MemoryPool.Unknown, 0, 0);
HeapProperties upload_properties = new HeapProperties(HeapType.Upload, CpuPageProperty.Unknown, MemoryPool.Unknown, 0, 0);
long descSize = (long)Unsafe.SizeOf <MyRaytracingInstanceDescription>();
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);
buffers.InstanceDesc = CreateBuffer(device, descSize * instanceCount, ResourceFlags.None, ResourceStates.GenericRead, upload_properties);
tlasSize = info.ResultDataMaxSizeInBytes;
}
else
{
InsertUAVResourceBarrier(buffers.Result);
}
int instanceContr = 0;
MyRaytracingInstanceDescription[] instanceDescs = new MyRaytracingInstanceDescription[instanceCount];
for (int i = 0; i < instanceCount; i++)
{
instanceDescs[i] = new MyRaytracingInstanceDescription();
float xPos = (i - 1) * 1.5f;
float yPos = 0.0f;
float zPos = 0.0f;
instanceDescs[i].Transform = Matrix4x4.Identity;
if (i != 1)
{
instanceDescs[i].Transform *= Matrix4x4.CreateRotationY(rotate);
if (i == 2)
{
zPos = -0.5f;
}
}
instanceDescs[i].Transform *= Matrix4x4.CreateTranslation(xPos, yPos, zPos);
instanceDescs[i].Transform = Matrix4x4.Transpose(instanceDescs[i].Transform);
instanceDescs[i].InstanceID = i;
instanceDescs[i].InstanceContributionToHitGroupIndex = instanceContr;
instanceDescs[i].Flags = (byte)RaytracingInstanceFlags.None;
instanceDescs[i].InstanceMask = 0xFF;
if (i == 1)
{
instanceDescs[i].AccelerationStructure = bottomLevelAS[0].GPUVirtualAddress;
instanceContr += 4;
}
else
{
instanceDescs[i].AccelerationStructure = bottomLevelAS[1].GPUVirtualAddress;
instanceContr += 2;
}
}
IntPtr data = buffers.InstanceDesc.Map(0, null);
Helpers.CopyMemory <MyRaytracingInstanceDescription>(data, new ReadOnlySpan <MyRaytracingInstanceDescription>(
instanceDescs));
buffers.InstanceDesc.Unmap(0, null);
BuildRaytracingAccelerationStructureDescription asDesc = new BuildRaytracingAccelerationStructureDescription();
asDesc.Inputs = inputs;
asDesc.Inputs.InstanceDescriptions = buffers.InstanceDesc.GPUVirtualAddress;
asDesc.DestinationAccelerationStructureData = buffers.Result.GPUVirtualAddress;
asDesc.ScratchAccelerationStructureData = buffers.Scratch.GPUVirtualAddress;
if (isUpdate)
{
asDesc.Inputs.Flags |= RaytracingAccelerationStructureBuildFlags.PerformUpdate;
asDesc.SourceAccelerationStructureData = buffers.Result.GPUVirtualAddress;
}
commandList.BuildRaytracingAccelerationStructure(asDesc);
InsertUAVResourceBarrier(buffers.Result);
}
