Hey,

I have a problem with initializing BLAS with DX12. What is failing is function - BuildRaytracingAccelrationStructure.
Here is an error:

D3D12 ERROR: ID3D12CommandList::BuildRaytracingAccelerationStructure: D3D12_RAYTRACING_GEOMETRY_DESC[0].Triangles.IndexBuffer + SizeInBytes - 1 (0x000000000714b08f) exceeds end of the virtual address range of Resource (0x0000026741E0AB50:'Unnamed ID3D12Resource Object', GPU VA Range: 0x000000000714b000 - 0x000000000714b01f). [ RESOURCE_MANIPULATION ERROR #1158: BUILD_RAYTRACING_ACCELERATION_STRUCTURE_INVALID]

D3D12: **BREAK** enabled for the previous message, which was: [ ERROR RESOURCE_MANIPULATION #1158: BUILD_RAYTRACING_ACCELERATION_STRUCTURE_INVALID ]

Here is full function. Exception is thrown at the very end of it:

void Renderer::CreateBLAS(std::shared_ptr<ModelClass> model)
{
    // Describe the geometry that goes in the bottom acceleration structure(s)
    D3D12_RAYTRACING_GEOMETRY_DESC geometryDesc{};
    geometryDesc.Type = D3D12_RAYTRACING_GEOMETRY_TYPE_TRIANGLES;
    geometryDesc.Triangles.VertexBuffer.StartAddress = model->GetVertexBuffer()->GetGPUVirtualAddress();
    geometryDesc.Triangles.VertexBuffer.StrideInBytes = model->GetVertexBufferView().StrideInBytes;
    geometryDesc.Triangles.VertexCount = static_cast<UINT>(model->GetMesh(0).vertices.size());
    geometryDesc.Triangles.VertexFormat = DXGI_FORMAT_R32G32B32_FLOAT;
    geometryDesc.Triangles.IndexBuffer = model->GetIndexBuffer()->GetGPUVirtualAddress();
    geometryDesc.Triangles.IndexFormat = model->GetIndexBufferView().Format;
    geometryDesc.Triangles.IndexCount = static_cast<UINT>(model->GetIndicesCount());
    geometryDesc.Triangles.Transform3x4 = 0;
    geometryDesc.Flags = D3D12_RAYTRACING_GEOMETRY_FLAG_OPAQUE;

    D3D12_RAYTRACING_ACCELERATION_STRUCTURE_BUILD_FLAGS buildFlags = D3D12_RAYTRACING_ACCELERATION_STRUCTURE_BUILD_FLAG_PREFER_FAST_TRACE;

    // Get the size requirements for the BLAS buffers
    D3D12_BUILD_RAYTRACING_ACCELERATION_STRUCTURE_INPUTS ASInputs = {};
    ASInputs.Type = D3D12_RAYTRACING_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL;
    ASInputs.DescsLayout = D3D12_ELEMENTS_LAYOUT_ARRAY;
    ASInputs.pGeometryDescs = &geometryDesc;
    ASInputs.NumDescs = 1;
    ASInputs.Flags = buildFlags;

    D3D12_RAYTRACING_ACCELERATION_STRUCTURE_PREBUILD_INFO ASPreBuildInfo = {};
    m_device->GetRaytracingAccelerationStructurePrebuildInfo(&ASInputs, &ASPreBuildInfo);

    ASPreBuildInfo.ScratchDataSizeInBytes = ALIGN(D3D12_RAYTRACING_ACCELERATION_STRUCTURE_BYTE_ALIGNMENT, ASPreBuildInfo.ScratchDataSizeInBytes);
    ASPreBuildInfo.ResultDataMaxSizeInBytes = ALIGN(D3D12_RAYTRACING_ACCELERATION_STRUCTURE_BYTE_ALIGNMENT, ASPreBuildInfo.ResultDataMaxSizeInBytes);

    // Create the BLAS scratch buffer
    auto bufferInfo = CD3DX12_RESOURCE_DESC::Buffer(ASPreBuildInfo.ScratchDataSizeInBytes, D3D12_RESOURCE_FLAG_ALLOW_UNORDERED_ACCESS, D3D12_RESOURCE_STATE_UNORDERED_ACCESS);
    bufferInfo.Alignment = std::max(D3D12_RAYTRACING_ACCELERATION_STRUCTURE_BYTE_ALIGNMENT, D3D12_DEFAULT_RESOURCE_PLACEMENT_ALIGNMENT);

    ThrowIfFailed(m_device->CreateCommittedResource(
        &CD3DX12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_DEFAULT),
        D3D12_HEAP_FLAG_NONE,
        &bufferInfo,
        D3D12_RESOURCE_STATE_COMMON,
        nullptr,
        IID_PPV_ARGS(&m_blasScratch)
    ));

    // Create the BLAS buffer
    bufferInfo = CD3DX12_RESOURCE_DESC::Buffer(ASPreBuildInfo.ResultDataMaxSizeInBytes, D3D12_RESOURCE_FLAG_ALLOW_UNORDERED_ACCESS, D3D12_RESOURCE_STATE_RAYTRACING_ACCELERATION_STRUCTURE);
    bufferInfo.Alignment = std::max(D3D12_RAYTRACING_ACCELERATION_STRUCTURE_BYTE_ALIGNMENT, D3D12_DEFAULT_RESOURCE_PLACEMENT_ALIGNMENT);

    ThrowIfFailed(m_device->CreateCommittedResource(
        &CD3DX12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_DEFAULT),
        D3D12_HEAP_FLAG_NONE,
        &bufferInfo,
        D3D12_RESOURCE_STATE_COMMON,
        nullptr,
        IID_PPV_ARGS(&m_blasResult)
    ));

    // Describe and build the bottom level acceleration structure
    D3D12_BUILD_RAYTRACING_ACCELERATION_STRUCTURE_DESC buildDesc = {};
    buildDesc.Inputs = ASInputs;
    buildDesc.ScratchAccelerationStructureData = m_blasScratch->GetGPUVirtualAddress();
    buildDesc.DestAccelerationStructureData = m_blasResult->GetGPUVirtualAddress();

    m_commandList->BuildRaytracingAccelerationStructure(&buildDesc, 0, nullptr);

    // Wait for the BLAS build to complete
    D3D12_RESOURCE_BARRIER uavBarrier;
    uavBarrier.Type = D3D12_RESOURCE_BARRIER_TYPE_UAV;
    uavBarrier.UAV.pResource = m_blasResult.Get();
    uavBarrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
    m_commandList->ResourceBarrier(1, &uavBarrier);
}

And here is ModelClass class, which I'm passing to function creating BLAS. PrepareBuffers is used to provide vertex/index buffers and buffer views stored in ModelClass:

bool ModelClass::PrepareBuffers(ComPtr<ID3D12Device2> device)
{
	Mesh mesh = GetMesh(0);

	const UINT vertexBufferSize = static_cast<UINT>(sizeof(ModelClass::VertexBufferStruct)) * static_cast<UINT>(mesh.vertices.size());

	ThrowIfFailed(device->CreateCommittedResource(
		&CD3DX12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_UPLOAD),
		D3D12_HEAP_FLAG_NONE,
		&CD3DX12_RESOURCE_DESC::Buffer(vertexBufferSize),
		D3D12_RESOURCE_STATE_GENERIC_READ,
		nullptr,
		IID_PPV_ARGS(&m_vertexBuffer)));

	// Copy the triangle data to the vertex buffer.
	UINT8* pVertexDataBegin;
	CD3DX12_RANGE readRange(0, 0);        // We do not intend to read from this resource on the CPU.
	ThrowIfFailed(m_vertexBuffer->Map(0, &readRange, reinterpret_cast<void**>(&pVertexDataBegin)));
	memcpy(pVertexDataBegin, &mesh.vertices[0], vertexBufferSize);
	m_vertexBuffer->Unmap(0, nullptr);

	// Initialize the vertex buffer view.
	m_vertexBufferView.BufferLocation = m_vertexBuffer->GetGPUVirtualAddress();
	m_vertexBufferView.StrideInBytes = sizeof(ModelClass::VertexBufferStruct);
	m_vertexBufferView.SizeInBytes = vertexBufferSize;

	// Create index buffer
	const UINT indexBufferSize = sizeof(mesh.indices);
	m_indicesCount = static_cast<UINT>(mesh.indices.size());

	ThrowIfFailed(device->CreateCommittedResource(
		&CD3DX12_HEAP_PROPERTIES(D3D12_HEAP_TYPE_UPLOAD),
		D3D12_HEAP_FLAG_NONE,
		&CD3DX12_RESOURCE_DESC::Buffer(indexBufferSize),
		D3D12_RESOURCE_STATE_GENERIC_READ,
		nullptr,
		IID_PPV_ARGS(&m_indexBuffer)));

	// Copy the triangle data to the vertex buffer.
	UINT8* pIndexDataBegin;
	ThrowIfFailed(m_indexBuffer->Map(0, &readRange, reinterpret_cast<void**>(&pIndexDataBegin)));
	memcpy(pIndexDataBegin, &mesh.indices[0], sizeof(mesh.indices));
	m_indexBuffer->Unmap(0, nullptr);

	// Initialize the vertex buffer view.
	m_indexBufferView.BufferLocation = m_indexBuffer->GetGPUVirtualAddress();
	m_indexBufferView.Format = DXGI_FORMAT_R32_UINT;
	m_indexBufferView.SizeInBytes = indexBufferSize;

	return true;
}

Thank you in advance. I am using code from this repository - https://github.com/microsoft/DirectX-Graphics-Samples/blob/master/Samples/Desktop/D3D12Raytracing/src/D3D12RaytracingHelloWorld/D3D12RaytracingHelloWorld.cpp​ which is part of RayTracing Gems books - http://www.realtimerendering.com/raytracinggems/unofficial_RayTracingGems_v1.7.pdf

Sorry for the problem, I managed to solve it. In case if someone have similar problem:

const UINT indexBufferSize = mesh.indices.size() * 4;

Code was lacking multiplication by 4. My index buffer format is DXGI_FORMAT_R32_UINT, which indicates usage of 4 bytes. If I understand correctly, for DXGI_FORMAT_R16_UINT, you need to multiply by 2 to ensure correct results.

Thread can closed.