Copy texture data from gpu to cpu with Direct3D 11

Copy.cpp

int const Width = 16;
int const Height = 16;


/////////////////////
// Create Textures //
/////////////////////

ID3D11Texture2D * Texture = nullptr;
ID3D11Texture2D * Staging = nullptr;

D3D11_TEXTURE2D_DESC TexDesc;
TexDesc.Width = Width;
TexDesc.Height = Height;
TexDesc.MipLevels = 0;
TexDesc.ArraySize = 1;
TexDesc.Format = DXGI_FORMAT_R32_FLOAT;
TexDesc.SampleDesc.Count = 1;
TexDesc.SampleDesc.Quality = 0;
TexDesc.BindFlags = 0;
TexDesc.MiscFlags = 0;
TexDesc.Usage = D3D11_USAGE_DEFAULT;
TexDesc.CPUAccessFlags = 0;

Device->CreateTexture2D(& TexDesc, NULL, & Texture);

TexDesc.Usage = D3D11_USAGE_STAGING;
TexDesc.CPUAccessFlags = D3D11_CPU_ACCESS_READ;

Device->CreateTexture2D(& TexDesc, NULL, & Staging);


/////////////////
// Upload Data //
/////////////////

FLOAT * Data = new FLOAT[Width * Height]();

for (int i = 0; i < Width; ++ i)
{
	for (int j = 0; j < Height; ++ j)
	{
		Data[i + j * Width] = (float) i + (float) j / 1000.f;
	}
}

UINT const DataSize = sizeof(FLOAT);
UINT const RowPitch = DataSize * Width;
UINT const DepthPitch = DataSize * Width * Height;

D3D11_BOX Box;
Box.left = 0;
Box.right = Width;
Box.top = 0;
Box.bottom = Height;
Box.front = 0;
Box.back = 1;

ImmediateContext->UpdateSubresource(Texture, 0, & Box, Data, RowPitch, DepthPitch);
delete[] Data;


///////////////////
// Download Data //
///////////////////

ImmediateContext->CopyResource(Staging, Texture);

FLOAT * Read = new FLOAT[Width * Height]();

for (int i = 0; i < Width; ++ i)
{
	for (int j = 0; j < Height; ++ j)
	{
		Read[i + j * Width] = -1.f;
	}
}


D3D11_MAPPED_SUBRESOURCE ResourceDesc = {};
ImmediateContext->Map(Staging, 0, D3D11_MAP_READ, 0, & ResourceDesc);

if (ResourceDesc.pData)
{
	int const BytesPerPixel = sizeof(FLOAT);
	for (int i = 0; i < Height; ++ i)
	{
		std::memcpy(
			(byte *) Read               + Width * BytesPerPixel * i,
			(byte *) ResourceDesc.pData + ResourceDesc.RowPitch * i,
			Width * BytesPerPixel);
	}
}

ImmediateContext->Unmap(Staging, 0);

for (int i = 0; i < Width; ++ i)
{
	for (int j = 0; j < Height; ++ j)
	{
		printf("[%d, %d] = { %.6f }\n", i, j, Read[i + j * Width]);
	}
}

delete[] Read;