I have a map with a sewer system that functions very similarly to the tunnels in CS_MILITIA, where one end of the underground tunnel is near the spawn, there are muliple exits in the middle of the tunnel, and the other end comes out behind the opponent's spawn. This means that the sewers touch most of areas of the map.

Using mat_wireframe, I can see that the sewers are rendering almost all the time, despite the fact that they should almost never be visible.

When I close the sewers in with area portals, I get a set of errors for each func_areaportal, saying that it "doesn't touch two areas". There is a .LIN file created.

If I follow the .LIN file, it makes a complete circuit of the map. It crosses into one sewer entry, and out of another sewer entry, both of which have area portals covering them. (and therefore, I don't understand the algorithm like I thought I did.)

Is it possible that there is a volume limit to the size of any area covered by an area portal, and once you use an area portal, you have to manage the space around them?

The map doesn't have leaks. The areaportals to not cross water. They are covered on all sides by the areaportal texture. They all snugly fit in rectangular openings that are on the grid. They are all func_areaportal, set to Always Open. When the map renders, despite the "Open" setting, the areaportals are transparent, and show through to void, although once you cross through them they work fine.

I've used hint brushes, and they do not stop vis from rendering the sewers despite the fact that they are never visible except under very specific conditions.

Thanks in advance for any help.

(I wish we could prune the VIS tree the same way we make mods to the NAV tree. It would be difficult, but interesting. And it would give us the control we need over our maps.)

[edit: changed On to Open)

I didn't build a dummy-box around the sewers. There is some other limitation to vis and areaportals... something like volume enclosed, or lin-distance, or something of that nature.

Anyway, I cannot get vis to stop rendering the sewers. Hints, areaportals, nothing.

I was wondering if it's that the ladder brushes extend up and down into both spaces?

Any ideas please. This is exasperating. I need to get about 10% of a performance increase out of this map, and it's all because I'm getting areas rendered that are out of sight.

Could you use noclip to zoom out then take a pic of the shape of your sewer system? How far is it from the sewers up to ground level above? For all we know the sewers could be in a straight line and directly connect onto the ground level above ie with no short section of tunnel to help block vis), in which case visibility won't be blocked and hint brushes won't help.

Yes, that's close to the issue. Thank you.

I closed off all the areas, but the inter-area leak wasn't from an areaportal, but from the geometry between the area portals. I just didn't catch it because the line was so long and circuitous. I got about a 5fps performance increase by better sealing the areas of the map off from openings I wasn't aware of because they were behind an unintuitive func_detail entity.

I made a huge test map of three large areas, connected by six tunnels, and then ran a number of scenarios using areaportals, and leaks between areas. HL3 is great because can get a lin file and a leak warning by exposing your map to the void. But, until you use areaporals, you haven't sealed off areas of your map from each other. Really though, unless you're actually using doors, areaportals seem kind of silly to me, They help seal the level areas off from one another, and help you debug, but most of the Tut's pitch them as advanced hint brushes for controlling vis, but they really don't function well in that capacity.

Desite closing off different areas of the map, I still cannot get the sewers to stop rendering. I'll post the map as a beta in the next week or so, and see what people have to recommend.

-Cheers and thanks for the help.