Pathfinding in a 3d point'n'click adventure?

For this case I would sugest to use 2D A Star pathfinding.

This means it won't be possible to have the character explore multiple levels (of a building) with the same pathfinding obstacles information. If you want him to walk on multiple levels, you need to use multiple layers of obstacle information.

First you need to put the obstacles information into an array or Type construnct to make it accessible by the A-Star Algorithm. I would do this with a Linepick System that would detect any obstacles.

Then you would have to implement the A-Star Algorithm in a way that allows to apply the resutlting route to the character.

Here's some A-Star code:

http://www.blitzcoder.com/cgi-bin/showcase/showcase_showentry.pl?id=turtle177604062002002208&comments=no

http://www.blitzcoder.com/cgi-bin/showcase/showcase_showentry.pl?id=morduun12202002081940&comments=no

http://geocities.com/joepitto/RpgRealm.html

http://www.blitzcoder.com/cgi-bin/showcase/showcase_showentry.pl?id=suremapper02182005162911&comments=no

But: Implementing the thing you want is not easy, so don't underestimate it. If you are not familar with Blitz3Ds commands and their usage, first learn them. If you don't know how to use Linepicks to create an array of obstacles, then you need to learn the basics first.