Thinmesh in Easygen not recommended?

(Ubiquitous) #1

I have seen this thought expressed in many threads of easygen. Usually the poster will invoke the mighty ydnar and say, “ydnar said it was a bad idea”. I looked through the q3map2 support forum with the query “thin mesh”, and I didn’t really get any results. So if you have a little time ydnar, could you explain why the thin mesh option is a bad idea when it comes to generating terrain in easygen. This thin mesh would be invaluable for me, as I plan on making a tunnel connecting the two sides of my map. I also have many buildings that will need to match up with the terrain, and it seems it would be easier if you had only one layer of terrain brushes to cut through.

(ydnar) #2

Thin mesh terrain creates a much larger BSP and is slower at runtime for collision detection.

Clipping out the bottoms of certain terrain triangle brushes to make tunnels isn’t that hard.

y

(BadIdea) #3

Why?
One difference is : bottom brushes have many different angles - is this a problem?
But Caulk is Caulk (?).
Thin terrain- affect gameplay? fps ?
And second question: does worldspawn/structural brushes cutting a terrain during bsp/vis?
F.e Caulk boxes in mountains, angled structural brushes etc.

Can I use a - skip, nodraw shader in place caulk in non action areas?(collision detection)
Terrain - colisions - we need this only on top faces of terrain entity (with terrain shader)

Sorry for my English.

(ydnar) #4

Caulk is solid, and opaque to vis and lighting calculations. The latter is important for better lighting.

If you use thin-mesh terrain, then the number of unique planes in the BSP nearly doubles. This can and will slow down collision detection, and therefore performance, on the map.

Sure, there are ways you can optimize around it, but the best way is to just not use thin mesh terrain. Chop what you need to, leave the rest alone.

y

(BadIdea) #5

Thx ydnar.
Btw - your Cfg file - is great :slight_smile:

(damocles) #6

Can you not simply use nodraw-nonsolid instead of caulk for the underside of terrains? Then only the top surface would be used for collision calculation.

Edit:

Just did a little test, nope you cannot use nodraw nonsolid. It seems the collision data isn’t taken from the terrain surfaces but instead from the individual brushes, so each triangle will most likely be nonsolid :confused:

So yep, thick meshes are best, but really annoying to use when you want to do a lot of underground stuff :confused:

(fraco) #7

hi,

I hope someone is able to enlighten me.

I have no clue what thinmesh is. Thing is I have an easygen generated terrain, and am worried that this might apply to my map.

And what is collision detection? Is this the game engine limiting the player movement (blocking the player). Does this thread say that the caulk under my terrain brushes will slow down the calculation of player movement and aversely affect performance. Would it then be a good idea to use _skip instead of _caulk?

I know, I have no clue what I am talking about. I’d really appreciate if someone could bring my knowledge up to speed a bit.

fraco

(damocles) #8

We were saying you should use caulk under the terrain, but when you export the terrain, do NOT select the thin mesh option in easygen.

If you think your terrain is using thin mesh, in radiant move under the terrain. If it consists of loads of tall blocks of caulk, you are fine. If you can see the underside of your terrain in the shape your terrain is, then you have a thin mesh.