I think the title speaks for itself

Portals are a way to cull large portions of your geometry. It basically works like this: If I''m in a room, I can only see what is through the door and windows (portals.)

I can''t go into it in-depth in a short amount of space, but here are some resources:

Seth Tellar''s thesis: "Visibility Computations in Densley Occluded Polyhedral Environments,"

Cuban Perez''s "Peeking Through Portals" in March 98 Game Developer, or online at his website, www.cubonics.com

And http://www.netmagic.net/~achalfin/Graphics/portal.htm, not sure if it''s still there.

There is a tutorial on Flipcode, stay away from it, I found it less than satisfactory.

Is the Unreal engine, a portal engine, could yo name some portal engines please, sounds pretty cool, and Ive been thinking about doing something like that lately 2, thanks

I believe Unreal uses portals, but it''s not a pure portal engine, it uses BSP also.
The Quake engine also uses portals, but at a preprocessing stage, but 3D realms Prey engine is a pure
portal engine.

Greets Tobias

Unreal and Quake use something called "sector portals," rather than connecting convex cells, they connect large areas.

All the Descent''s use portals.

Any good tuts on them, also thanks

you could check out the windows game programmers Encyclopedia(sp?) at ftp.x2ftp.com

Edited by - Gromit on 2/2/00 1:35:17 AM

What is BSP?

Gandalf the White

BSP is a binary space partition.

Also the Crystalspace project is a open source portal engine. You can get a good look at the insides of that. Monster size download though.