Direct3D 11 Resources - Practical Rendering and Computation with Direct3D 11 - page 46

create a buffer that will be updated by the GPU with the stream output functionality. In
this case, the D3D11_USAGE_DEFAULT usage flag would be used. A sample buffer creation
process is provided in Listing 2.6 to demonstrate these options.

// Initialize the device using it...
ID3DllDevice* g_pDevice = 0;

ID3DllBuffer* CreateVertexBuffer( UINT size,
bool dynamic,
bool streamout,
D3D11_SUBRES0URCE_DATA* pData )

{

D3D11_BUFFER_DESC desc;
desc.ByteWidth = size;
desc.MiscFlags = 0;
desc.StructureByteStride = 0;

// Select the appropriate binding locations based on the passed in flags
if ( streamout )
desc.BindFlags = D3D11_BIND_VERTEX_BUFFER | D3D11_BIND_STREAM_0UTPUT;
else
desc.BindFlags = D3D11_BIND_VERTEX_BUFFER;

// Select the appropriate usage and CPU access flags based on the passed
// in flags
if ( dynamic )
{

desc.Usage = D3D11_USAGE_DYNAMIC;
desc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;

}
else
{

desc.Usage = D3D11_USAGE_IMMUTABLE;
desc.CPUAccessFlags = 0;

}
// Create the buffer with the specified configuration
ID3D11Buffer* pBuffer = 0;
HRESULT hr = g_pDevice->CreateBuffer( &desc, pData, &pBuffer );

if ( FAILED( hr ) )
{

// Handle the error here...
return( 0 );

}
return( pBuffer );

Listing 2.6. A method for creating vertex buffers with various usage considerations.