Gets a pointer to the array of constants in the constant table.
HRESULT GetConstantDesc( D3DXHANDLE hConstant, D3DXCONSTANT_DESC * pDesc, UINT * pCount );
If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be one of the following: D3DERR_INVALIDCALL, D3DXERR_INVALIDDATA.
Samplers can appear more than once in a constant table, therefore, this method can return an array of descriptions each with a different register index.
Header: Declared in D3dx9shader.h.