Camera in al scripta goes thru walls if not told to otherwise.

Morrow wing camera code has built in obstacle avoidance, as do some user examples.

A mate says Orange Brat went thru a lot to develop a 3rd person camera that worked well back then so perhaps you could find him and his thread and go thru that (its pretty big according to my mate here) for inspirstion and examples.

Other users post small camera snippets so search may yield good results too.

Also, Locoweed developed a 3rd person camera that could be stll available, I dont know as I never tried those solutions but was intending to research them soonish.