RE: [Algorithms] portal engines in outdoor environments

[Tom F. <to...@mu...>]

I agree - it's a nightmare case for geometric occlusion. Delayed Z-visiblity
is our only hope. A shame we've been waiting two DX versions for it, and
it's going to miss this one as well.  Grrrrrrr. So while we have fancy
vertex shaders that nothing on Earth supports, we don't have API support for
something that even crusty old hardware like Permedia2 and Voodoo1 supports.
Life... don't talk to me about life. :-)

Tom Forsyth - Muckyfoot bloke.
Whizzing and pasting and pooting through the day.

> -----Original Message-----
> From: Charles Bloom [mailto:cb...@cb...]
> Sent: 18 August 2000 18:26
> To: gda...@li...
> Subject: [Algorithms] portal engines in outdoor environments
> 
> 
> 
> .. is a hopeless proposition, I think.  I'd just like you
> guys to check my reasoning before I give up.  Consider,
> for example, a building placed on a landscape.  The goal
> is to construct portals so that when you stand on one
> side of the building, you can't see the other.  If the
> player is constrained to stay on the ground, this is
> easy enough, it's really a 2d occlusion problem, and you
> need 8 portals (two * 4 faces of a square in 2d; two portals
> cuz you need one on each side of a face of the square,
> parrallel to that face) which splits the universe into 9
> zones (8 outside and one inside the occluding cube).
> 
> However, if we have a plain cube in 3d and the player can
> go anywhere around it, we need 48 portals !! (8 for each of
> the 6 faces on the cube).  Now if you have two cubes near
> eachother, you need massive numbers of portals, and they
> must all not intersect with eachother or other geometry.
> This quickly becomes unworkable.
> 
> I think something like a "real-time" occcluder (shadow volumes,
> etc.) is the only hope for outdoors.
> 
> --------------------------------------
> Charles Bloom           www.cbloom.com