Sets the track weight. The weight is used to determine how to blend multiple tracks together.
HRESULT SetTrackWeight( [in] UINT Track, [in] FLOAT Weight );
Identifier of the track to set the weight on.
If the method succeeds, the return value is S_OK. If the method fails, the return value can be one of the following values: D3DERR_INVALIDCALL, E_OUTOFMEMORY.