HRESULT SetField(D3DVALUE rvField);
Sets the field of view for a viewport.
·Returns D3DRM_OK if successful, or an error otherwise. For a list of possible return codes, see Direct3D Retained-Mode Return Values.
rvField
New field of view. The default value is 0.5. If this value is less than or equal to zero, this method returns the D3DRMERR_BADVALUE error.