I have a couple of questions. I figured out some real dirty hacks for them, but I''m looking for more elegant solutions. If anyone has any suggestions, please reply. 1. How can I figure out an equation for the back clipping plane from the camera transformation matrix? I need this to clip geometry behind it that I render manually. 2. I have a camera system set up that uses local coordinate axes. For every object I keep the up, view and right vectors and when I need to change the transformation I just rotate two vectors around one. Then I just get the transformation matrix from these three vectors. Now, for the FPS style camera the user can''t look up higher then 89 degrees and can''t look down lower then 89 degrees otherwise he''ll flip (and that''s unwanted). How do I prevent this flipping? I only have the three vectors and the degree to rotate by, nothing else. Thanks.

The dot product is our friend, because its fast to compute. The dot product of two normalized vectors will give you the cosine of the angle between them. If the dot product of the forward vector and the vector from the eye to a point is less than cos(FOV), you know the point is outside the field of view.

Similarly you can figure out the deviation of the forward vector from the xz plane and constrain accordingly.