Create an effect pool. A pool is used to share parameters between effects.
HRESULT D3DXCreateEffectPool( LPD3DXEFFECTPOOL* ppPool );
If the method succeeds, the return value is S_OK.
If the arguments are invalid, the method will return D3DERR_INVALIDCALL.
If the method fails, the return value will be E_FAIL.
For effects within a pool, shared parameters with the same name share values.
Header: Declared in D3dx9effect.h.