In a 3d game how would I create some sort of tracing collision detection for like, shooting guns or weapons at objects. Please help I don''t know what to do, I apprecieate any help. THX, JAP

Try to find an open-source physics engine. There is one posted in the news.

Scott Simontis
Big Joke: C#

You take the ray (in mathematic terms) that the bullet trace during the last virtual time increment (e.g. Quake runs with about 15 physics steps per second, and interpolates the graphics between physics updates) and perform collision detection againt the world with it (ultimately line-triangle intersection tests).

Making it fast means having a heirachical organization of the contents of the world, so large portions of the world can quickly be rejected as potential collisions. e.g. By using a sphere tree, oct-tree, BSP-tree, or combinations.