Hi there, I am starting a portal engine with openGL. Let's say we have a window to the next room in our current room. "We have a window to the next room in our current room." <img src='icons/icon12.gif'; And the window is visible. So i calculate four additional clipping planes and add them with void glClipPlane( GLenum plane, const GLdouble equation );. After that the contents of the next room is sent to the pipline. Will this speed up the rendering of the room? Are Clipping Planes accelerated by the hardware? Digging my grave Edited by - TheMummy on 1/11/00 8:57:09 AM Edited by - TheMummy on 1/11/00 8:58:14 AM