been messing with fog a bit, gots questions

[sleepy1212]

i want to surround a bsp with fog but not have any in the actual gameplay area.

so far i've only managed to get the fog region error which i think might have to so with material/geometry name setup but im not convinced.

first off i tried making several boxes with portal material, but that doesn't work without intersecting the bsp and its not possible to have all planes do that at once without major errors.

next attempts involved using +unused or +unused$ on the same boxes but that doesn't work either.

i guess what i'm shooting for is a way to define clusters outside/intersecting the bsp where i might be able to use a fog plane. the only thing i haven't tried is using terrain portals to cut off the outermost parts of the skybox but i was worried about clipping.


while i'm on the portals i've got this one too: my exact portals error on every run through tool but never in the same place. i can run it twice without changing anything and there will be the same error but on a different plane. i threw them out and used +portal but that doesn't keep it from raining inside :\ i'm guessing that won't help with the fog either.......

[chrisk123999]

Fog in halo is either everywhere no nowhere. Your best bet would to make the atmosphere fog start farther away and get thicker quickly. You can have more then one fog plane, but when your in an area where you removed the fog from that portal, you don't see the fog in the other area.

[neuro]

fog is everywhere or nowhere, yes, but only PER CLUSTER. (defined by portals)

also, exact portals need to be planar

[sleepy1212]

exact portals need to be planar

sweet, an easy fix. i love it when that happens :D

@ chrisk: that's basically what i'm after, i need very thick fog around the outside to quickly turn to thin or no fog. i'll have to take a look at some tags and see what i can use, any good starting places?

[chrisk123999]

Well, that's also the problem. Once your not in a the fog, you can see into the other area where there should be fog and there won't be any there.

[sleepy1212]

hmm. i wonder if i could change the opacity or density in a fog tag to make it become very thick but only at a far distance, if it starts from the player i would only have to make sure the distance is far enough to cover all areas the player can go. that would save me the trouble of using a lot of effedup geometry.

[chrisk123999]

You can set the starting distance and the ending distance (where you can't see though it at all). Look at some other sky tags as a reference.

[Rob Oplawar]

Well, that's also the problem. Once your not in a the fog, you can see into the other area where there should be fog and there won't be any there.

I'm not sure this is true. Think of maps like Damnation- it has a fog plane at the bottom where the fog gets pretty thick immediately. My understanding was that Blam! has very limited capabilities in terms of defining fog regions, however. A year or two ago I wouldn't have thought it possible to define fog regions surrounding but not intersecting a playable area, but these days I've come to realize people can really push this engine, and there's definitely still a lot I don't know about how it works. Theoretically I think you should be able to set fog on the clusters surrounding the playable area and leave the ones in the play area empty.
Then again, I remember something about creating specific fog planes separate from portals, and iirc the entire fog 'plane' has to be planar, ie, the fog region can't wrap around.

I say keep trying, though. I'll be interested to know if this can be done.

[FRain]

Although if you wanted to simulate fog out in the distance that you cant actually reach, you could probably just make some geometry to simulate it and then apply the fog materials to it.

Then again, that's not volumetric and only if you aren't supposed to be out in that playing area.

[Dwood]

Although if you wanted to simulate fog out in the distance that you cant actually reach, you could probably just make some geometry to simulate it and then apply the fog materials to it.

Then again, that's not volumetric and only if you aren't supposed to be out in that playing area.

Revelations.

[chrisk123999]

There are 2 fogs you can use, atmosphere fog and a fog plane. The fog plane has to go in a strait line and can not wrap around. It's most commonly used for water. When your in a cluster with a fog plane assigned to it, you will see fog everywhere at the level with the fog plane. However if you had a cluster right next to it without fog assigned to it, you won't see any fog even where it is supposed to be in the other cluster.

[Dwood]

Make clusters with little fog (ie in the center) that takes a long distance to get foggy, then increase the amount of fog that shows per cluster as the player goes out?

[sleepy1212]

i just had a thought about using clusters in the first place. one of my unreleased levels i made as several rooms, each a separate model that i brought into one model and Attached them to one element and linked. it works great and cuts down on rendering (52000 poly, ca 7000/room).

thing is the reason this works is that the only thing that gets rendered is the room that the camera is in. its a pain in the ass to populate. what i'm thinking here is that chrisk was right and that the fog wouldn't draw unless the camera was in that cluster however it may if the clusters aren't defined by bsp elements and were defined by something else like portals.

atmospheric fog might be the way to go and i'm also going to try some 'creative' use of skybox.

[chrisk123999]

Culling is different then fog. The game will cull anything it thinks you the player can't see. Exact portals tend to get more stuff culled, but can't always be used. If you have multiple rooms like Chiron TL-34 the rooms your not in will get culled.

[sleepy1212]

i don't know why i picked this project up, i can't even see fog on my shitcomp. i usually rely on testers from my clan to help me out with this stuff but most of them aren't modders/modelers, well, two are developers but they don't have a lot of time to review my work. anyway, here's some of the work i have on this:

(includes maps, models, and all relevant tags)

Fog Experiment Files (http://www.4shared.com/file/193683089/a8a0807b/Fog_Experiment.html%3Cbr%20/%3E)

here's the maps if you're curious, but not that curious

Fog Experiment .maps (http://www.4shared.com/file/193686022/f243414b/fog_experiment_MAPS.html)

hopefully there's not too much fail in there lol. i know already that at least two may not work because the distance markers i used don't render which means the fog may not either. in one case the markers are actually outside the bsp so they don't render but the fog is in the sky.

i'd appreciate it if anyone who looks at these could put up some screenshots of the results. like i said before...shitcomp.

[sleepy1212]

ok got a new video card so i can finally see the results of my work.

so far it's 3/4 fail. modifiying the fog tag seems to have the most potential at this point. just needs some tweaking.

http://img.photobucket.com/albums/v389/sleepy1212/EXP_fog_tagingame.jpg

model for fog tag variant:

http://img.photobucket.com/albums/v389/sleepy1212/EXP_fog_tag.jpg

the atmospheric fog in the skytag: probably the model but could be tag settings

http://img.photobucket.com/albums/v389/sleepy1212/EXP_fog_atm_ingame.jpg

model for fog in sky tag:

http://img.photobucket.com/albums/v389/sleepy1212/EXP_fog_atm.jpg

these two involved the same model with exact portal and terrain portal materials. same fog tag as well. neither worked well but there seems to be some potential because there is fog in gameplay area (second ingame pic)

http://img.photobucket.com/albums/v389/sleepy1212/EXP_fog_skyboxEPTP01.jpg

http://img.photobucket.com/albums/v389/sleepy1212/EXP_fog_skyboxEPTP02.jpg

EP model

http://img.photobucket.com/albums/v389/sleepy1212/EXP_fog_skyboxEP.jpg

TP model

http://img.photobucket.com/albums/v389/sleepy1212/EXP_fog_skyboxTP.jpg

[sleepy1212]

Found more stuff...should have taken pics..oh well..


I think i've found why the fog only covered the floor in the above pics. Apparently it only draws between textures with opacity, not skybox or 100% transparent textures. I haven't tested intermediate opacity.

I made a cylinder around the bsp with a render only texture then capped it with a 100% transparent texture. In game there was fog between the player and [against] the sides of the cylinder but not the top and bottom. I could see straight through to the skybox as if there was no fog at all, even when i moved the camera to the cluster containing fog. When I changed the caps' texture to an opaque one I got fog in all directions, and throughout the game-play area.

The application here, to the desired effect in the OP, is to use a render only, uncapped cylinder (or have 100% alpha on the caps). Then make two additional planes above and below the cylinder with an opaque RO texture - but not intersecting the cylinder.

This will produce the effect that the game-play area is surrounded by fog but not in the fog itself.