really general question

how does one begin to go about programming the logic for barriers/floors/ceilings in opengl? for example, say i have a mountain, in general how could i make the camera crash into it, instead of flying through it?

You begin by learning about collision detection. It generally comes in different scales. For example, you would want to check if you could have collided with the mountain before checking if you collided with any particular rock of the mountain. Then possibly even further, checking which facet of the rock you collided with and what part of you collided with it. How you implement collision detection is dependent upon your needs. For example, for a landscape engine using a quadtree, or interior room based engine using a bsp, each would best handle collision detection in different ways.

[This message has been edited by DFrey (edited 01-29-2001).]