SubJeff on 11/9/2005 at 10:27
Has anyone experimented with Zone Portals? Does anyone know at what size is too large to make them useless? And in the wiki it says it's okay to be able to see through 2, but what about 3, 4, 5... ?
OrbWeaver on 11/9/2005 at 11:15
Assuming the portals work the same in T3 as they do in Doom 3, they perform occlusion in two main ways:
1) If a zone portal is not in the player's field of view, nothing beyond it is rendered. This has nothing to do with whether you can actually see the portal or not - it is still considered in the field of view if it is occluded by level geometry.
2) If a second zone portal lies beyond a first portal, the geometry beyond the second portal will only be rendered if the portals overlap in screen space.
I presume that it is the intersection of portals in screen space which is affected by the size of the portals; if the portals are large the game will have to examine a larger screen area for overlap. That said, I have not seen any objective comparison of large vs. small portal sizes so it is possible that the "don't use large portals" instruction is based on hearsay.
I don't see any problem with looking through a longer chain of portals; again, let FPS be your guide (I know that T3 is nothing like as efficient as Doom 3 so it may be that there are some things you cannot get away with as easily).
Krypt on 11/9/2005 at 19:41
The size doesn't matter as much as how they're arranged. They work pretty much as OrbWeaver described. You can make a portal as big as you want, but the bigger it is the more likely it is to get split into a bunch of smaller portals and the harder it becomes to set it up to actually occlude anything. If you have a really wide open space you usually will want to just put portals in the doorways leading out to it. Unless you have a 90 degree turn in your big area or something, you won't want to put a portal actually through the large part. If you do put a portal over a large area, make sure the BSP it intersects is as simple as you can manage, because it will split into more portals for every irregularity it hits, which can get messy (and slow) really quickly.
SubJeff on 11/9/2005 at 21:51
Thanks guys. I'll do some experiments and see how it works out.
