Hi !

I am trying to create a constant buffer for my shader and the variable “constantBufferUploadHeap” is nullptr after the "CreateCommittedResource" instruction with an error for “invalid parameter(s)”. I don't know if it comes from the alignment of data and if I have to add padding or not.

Here is my code :

struct VS_CONSTANT_BUFFER_G_BUFFER
{
	XMFLOAT4X4A viewWorld;
	XMFLOAT4X4A projViewWorld;
	bool normalMappingEnabled;
	bool padding[127];//in order to align data to 256 bytes
};

D3D12_HEAP_PROPERTIES heapProperties;
	heapProperties.Type = D3D12_HEAP_TYPE_UPLOAD;
	heapProperties.CPUPageProperty = D3D12_CPU_PAGE_PROPERTY_UNKNOWN;
	heapProperties.MemoryPoolPreference = D3D12_MEMORY_POOL_UNKNOWN;
	heapProperties.CreationNodeMask = 1;
	heapProperties.VisibleNodeMask = 1;

	D3D12_RESOURCE_DESC resourceDesc;
	resourceDesc.Dimension = D3D12_RESOURCE_DIMENSION_BUFFER;
	resourceDesc.Alignment = D3D12_CONSTANT_BUFFER_DATA_PLACEMENT_ALIGNMENT;// D3D12_DEFAULT_RESOURCE_PLACEMENT_ALIGNMENT;// ;
	resourceDesc.Width = sizeof(VS_CONSTANT_BUFFER_G_BUFFER);
	resourceDesc.Height = 1;
	resourceDesc.DepthOrArraySize = 1;
	resourceDesc.MipLevels = 1;
	resourceDesc.Format = DXGI_FORMAT_UNKNOWN;
	resourceDesc.SampleDesc.Count = 1;
	resourceDesc.SampleDesc.Quality = 0;
	resourceDesc.Layout = D3D12_TEXTURE_LAYOUT_ROW_MAJOR;
	resourceDesc.Flags = D3D12_RESOURCE_FLAG_NONE;

	HRESULT hr = deviceDX12->CreateCommittedResource(
		&heapProperties, // this heap will be used to upload the constant buffer data
		D3D12_HEAP_FLAG_NONE, // no flags
		&resourceDesc, // size of the resource heap. Must be a multiple of 64KB for single-textures and constant buffers
		D3D12_RESOURCE_STATE_GENERIC_READ, // will be data that is read from so we keep it in the generic read state
		nullptr, // we do not have use an optimized clear value for constant buffers
		IID_PPV_ARGS(&constantBufferUploadHeap));

	HRESULT hr2 = deviceDX12->GetDeviceRemovedReason();

	if (FAILED(hr))
		cout << "CreateCommittedResource failed " << endl;

	constantBufferUploadHeap->SetName(L"Constant Buffer Upload Resource Heap");

	D3D12_CONSTANT_BUFFER_VIEW_DESC constantBufferGBufferMatrices;
	constantBufferGBufferMatrices.BufferLocation = constantBufferUploadHeap->GetGPUVirtualAddress();
	constantBufferGBufferMatrices.SizeInBytes = sizeof(VS_CONSTANT_BUFFER_G_BUFFER);
	deviceDX12->CreateConstantBufferView(&constantBufferGBufferMatrices, mainDescriptorHeap->GetCPUDescriptorHandleForHeapStart());

I no longer need help, I found the solution.