light leaking under walls

[fraco]

yep,

I've seen a lot of topics on all different kinds of forums on this problem. And still I don't really understand. First some screenshots to show the problem:

general setup: a skybox, a ground surface and three "cabins":
http://home.planetinternet.be/~froidcoe/lightleak.jpg

now if you look into one of those cabins you see the light leak under the wall:
http://home.planetinternet.be/~froidcoe/lightleak01.jpg

or

http://home.planetinternet.be/~froidcoe/lightleak02.jpg

(i hope you can see it clearly, it's more obvious in-game)

in the second image I split the ground surface to create separate brushes (read somewhere that that should fix the problem). It doesn' change the problem.

The same shots with showtris, so you can see how my brushes are configured:

http://home.planetinternet.be/~froidcoe/lightleak01_tris.jpg

and

http://home.planetinternet.be/~froidcoe/lightleak02_tris.jpg

What I really want to know is where this comes from. I have some understanding of how the compiler works, but it is limited. Somehow I have the feeling it has something to do with some kind of roundoff error on the lightmap.

What is causing this? And of course how to fix it?

thnx
fraco[/b]

[Leslie Judge]

I'm not sure I can help but take a look at what I did: http://www.geocities.com/birolaszlo/lightbug.html

[sPUNKmonKEY]

I believe you can add 16x16 brushes (might be too thick but you'll have to play with the size depending on angle of light) that run the length of the sides that need the lightfix. The brushes can be textured with a shader that needs to be transparent, nonclipping, and yet has a castshadow (not certain of the tags). Basically it will act as a hidden entity that only helps to thicken the shadow cast by the wall.

[ydnar]

Adjacent coplanar brushes use the same lightmap. To avoid this, put the floor inside the cabins where you don't want a leak into a func_group.

Q3Map2 will not merge across func_group boundaries when projecting lightmaps. Additionally, if you have thin walls, you may have to add a _lightmapscale key to the func_group with a value of 0.75, 0.5 or 0.3, until the light leaks inside go away.

y

[Hewster]

Adjacent coplanar brushes use the same lightmap. To avoid this, put the floor inside the cabins where you don't want a leak into a func_group.

Q3Map2 will not merge across func_group boundaries when projecting lightmaps. Additionally, if you have thin walls, you may have to add a _lightmapscale key to the func_group with a value of 0.75, 0.5 or 0.3, until the light leaks inside go away.

y

Fantastic.. I wondered what the workaround to this would be :)

Is there not a shader command that would do the same thing ?
Me not like func_groups... I wouldn't mind if I could name and search for
them in radient though, like worldcraft does ?

Cheers

hewster

[Emon]

You can turn on the labeling so all entities have their names next to them...