Problem with gluPerspective view?

i am doing a viewer which has a basic navigation function, Pan, Rotate, and Zoom. At first i set up my current view with orthographic view. The gluUnProject works fine and able to maps the window coordinates to object coordinates. But after i switch to gluPerspective view, gluUnProject doesn’t maps to the right coordinate. Hope some one can show me how to solve this problem. Thanks

not an advanced question, but i think you’ll find that there’s a wealth of knowledge here if you only look…all it takes is a search.