D3D_FEATURE_LEVEL，D3D11_TEXTURE2D_DESC，D3D11_USAGE

1、typedef 
enum D3D_FEATURE_LEVEL
    { D3D_FEATURE_LEVEL_9_1 = 0x9100,
D3D_FEATURE_LEVEL_9_2 = 0x9200,
D3D_FEATURE_LEVEL_9_3 = 0x9300,
D3D_FEATURE_LEVEL_10_0 = 0xa000,
D3D_FEATURE_LEVEL_10_1 = 0xa100,
D3D_FEATURE_LEVEL_11_0 = 0xb000

    } D3D_FEATURE_LEVEL;

2、typedef struct D3D11_TEXTURE2D_DESC
    {
    UINT Width;
    UINT Height;
    UINT MipLevels;
    UINT ArraySize;
    DXGI_FORMAT Format;
    DXGI_SAMPLE_DESC SampleDesc;
    D3D11_USAGE Usage;
    UINT BindFlags;
    UINT CPUAccessFlags;
    UINT MiscFlags;
    } D3D11_TEXTURE2D_DESC;

3、typedef 
enum D3D11_USAGE
    { D3D11_USAGE_DEFAULT = 0,
D3D11_USAGE_IMMUTABLE = 1,
D3D11_USAGE_DYNAMIC = 2,
D3D11_USAGE_STAGING = 3
    } D3D11_USAGE;