Are the normalized device coordinates resulting from the projection transformation before the viewport transformation is done coordinates in world space on the view plane? I''m trying to generate a world-space vector along the view plane based on the movement of the mouse between frames. I was thinking I could just do an inverse viewport transformation on the mouse coords, which would yield the normalized device coordinates resulting from the projection that would place them at their screen locations, but that won''t work if the NDCs are not in world space. Does anyone have any suggestions? Thanks!