HRESULT SetPlane(D3DVALUE rvLeft, D3DVALUE rvRight, D3DVALUE rvBottom,
D3DVALUE rvTop);
Sets the dimensions of the viewport on the front clipping plane, relative to the camera's z-axis.
·Returns D3DRM_OK if successful, or an error otherwise. For a list of possible return codes, see Direct3D Retained-Mode Return Values.
rvLeft, rvRight, rvBottom, and rvTop
Minimum x, maximum x, minimum y, and maximum y coordinates of the four sides of the viewport.
Unlike the IDirect3DRMViewport::SetField method, which specifies a centered proportional viewport, this method allows you to specify a viewport of arbitrary proportion and position. For example, this method could be used to construct a sheared viewing frustum to implement a right- or left-eye stereo view.