D3D_FEATURE_LEVEL,D3D11_TEXTURE2D_DESC,D3D11_USAGE
1、typedef enumD3D_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_1