| Platform SDK: DirectX |
The Direct3DX hardware acceleration level constants are pre-defined indices that can be used wherever the actual device index is required. For example, hardware acceleration level constants can be used in the ID3DXContext::GetDeviceIndex method. Each constant indicates a different level of hardware acceleration.
The hardware acceleration level constants are an alternative to using the explicit device indexes retrieved by the global D3DXGetDeviceDescription function.
If one of the Direct3DX devices on the primary DirectDraw device supports a requested hardware acceleration level, it will be used. Otherwise, the first matching device found by Direct3DX will be used. Of course, it is possible for no match to exist for any of the hardware acceleration level constants on a particular system. Passing such a value into the Direct3DX APIs will simply cause them to fail, reporting that no match is available.
The hardware acceleration level constants should only be used as device indices under the following circumstance: a particular level of hardware acceleration is required by the application and, given more that one compatible device on the computer, it is not critical which one is used.