Bulding a portal engine...

Hey,

Im just curious what really goes into making a portal engine? Is it really simple as segmenting the level mesh, and the line picking sections with camera viewing angles and showing and hiding accordingly? Or is there something more such as using vector maths to speed up the line pick (heard that somewhere)?

I've come accross this article, any more help guys?
http://www.flipcode.com/portal/

Depends on what kind of portal you are talking about. Automaticly calculated visibility or manual placement?

I think with manual placement you can save all linepicks. Let's assume you would use bounding boxes: this will give you a list of boxes and all your engine would have to do is checking, if the camera is inside such a box. all boxes also have links to other portal boxes that are visible from the current locations box.

Since Map Design takes a lot of time anyway, I think it's not that hard to walk trough the level and enable/disable some boxes from each box - takes a few minutes.