Questions about vvis.

ToMoBoBo · 08-08-2012, 03:38 PM

So I've got these archways.

Here's what happens when I do make them func_detail.

Here's what happens when they're a world brush.

Maybe I'm misunderstanding but why are there so many more triangles cut on the brush above the arch when it's a func_detail? Shouldn't there be many less triangles?

Blueberry_pie · 08-08-2012, 11:24 PM

I'm not 100% sure, but it's my understanding that when multiple world brush faces form a single surface, the compiler will treat them as such and cut them up as it sees fit. But with func_detail brushes, the original brush faces will remain intact and won't be merged where possible. Additionally, VBSP will connect world brushes to detail brushes in the way you see on your screenshot, apparently to prevent visual glitches. You can turn that behaviour off with the -notjunc parameter, but in my opinion this is a better solution:

On the left is what I assume you have right now. By making the vertices join in the corners like on the right arch, you save a lot of polygons where the detail brush meets the world brush (not to mention on the arch itself).

zombie@computer · 08-09-2012, 01:46 AM

GPU's like to render everything in triangles, therefor any shape of a brush needs to be cut in triangles. Brushes sharing the same textures, offsets etc. (i think Valve calls these texinfos) are drawn in a batch; The game simply sends a bunch of points to the GPU (these dont even have to belong to the same brush!), then some texture information, then says 'render this ♥♥♥♥'. It is practically impossible to tell the difference between rendering 2000 or 3000 triangles in a single batch; All the triangles you see on your screenshots share the same texture properties (offset, texturename, rotation, etc), and are thus rendered in a single batch. The number of triangles on your hands, for instance, appear to be roughly 10-100 times as much as the triangles on the wall. The 'many more triangles' you see will cause a 0.0000000001% extra strain on the gpu. So you shouldn't worry about it. EVER.

ToMoBoBo · 08-09-2012, 08:29 AM

Wow thanks for the replies! Both make perfect sense. Blueberry_pie makes sense with the way he cut his arches, and zombie@computer just confirmed what I suspected (that it wasn't a big deal). I am going to try and recreate the brushwork though, to see if I can get fewer triangles out of the deal, because I have ~20 of these arches in my map.

When they are not func_detail, they actually make more triangles, but to the naked eye it looks like less.

I am just trying to learn all aspects of this stuff, and right now I'm working on a little optimization. I appreciate the knowledge brothers.

I'll see what happens with -notjunc.

OMG! It's everything I could dream of!

Blueberry_pie, how could you know? I looked up -notjunc on google, and there's nothing! Beast.

Blueberry_pie · 08-09-2012, 09:23 AM

Quote:

Originally Posted by ToMoBoBo

Blueberry_pie, how could you know? I looked up -notjunc on google, and there's nothing! Beast.

The developer wiki has info on all the parameters for every compile tool

ToMoBoBo · 08-09-2012, 10:22 AM

You are the man.

08-08-2012, 03:38 PM	#1
ToMoBoBo Join Date: Nov 2009 Reputation: 0 Posts: 31	Questions about vvis. So I've got these archways. Here's what happens when I do make them func_detail. Here's what happens when they're a world brush. Maybe I'm misunderstanding but why are there so many more triangles cut on the brush above the arch when it's a func_detail? Shouldn't there be many less triangles? Last edited by ToMoBoBo: 08-08-2012 at 03:42 PM.

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08-08-2012, 11:24 PM	#2
Blueberry_pie Join Date: Dec 2007 Reputation: 142 Posts: 1,455	I'm not 100% sure, but it's my understanding that when multiple world brush faces form a single surface, the compiler will treat them as such and cut them up as it sees fit. But with func_detail brushes, the original brush faces will remain intact and won't be merged where possible. Additionally, VBSP will connect world brushes to detail brushes in the way you see on your screenshot, apparently to prevent visual glitches. You can turn that behaviour off with the -notjunc parameter, but in my opinion this is a better solution: On the left is what I assume you have right now. By making the vertices join in the corners like on the right arch, you save a lot of polygons where the detail brush meets the world brush (not to mention on the arch itself).

08-09-2012, 01:46 AM	#3
zombie@computer Join Date: Aug 2008 Reputation: 416 Posts: 908	GPU's like to render everything in triangles, therefor any shape of a brush needs to be cut in triangles. Brushes sharing the same textures, offsets etc. (i think Valve calls these texinfos) are drawn in a batch; The game simply sends a bunch of points to the GPU (these dont even have to belong to the same brush!), then some texture information, then says 'render this ♥♥♥♥'. It is practically impossible to tell the difference between rendering 2000 or 3000 triangles in a single batch; All the triangles you see on your screenshots share the same texture properties (offset, texturename, rotation, etc), and are thus rendered in a single batch. The number of triangles on your hands, for instance, appear to be roughly 10-100 times as much as the triangles on the wall. The 'many more triangles' you see will cause a 0.0000000001% extra strain on the gpu. So you shouldn't worry about it. EVER.

08-09-2012, 08:29 AM	#4
ToMoBoBo Join Date: Nov 2009 Reputation: 0 Posts: 31	Wow thanks for the replies! Both make perfect sense. Blueberry_pie makes sense with the way he cut his arches, and zombie@computer just confirmed what I suspected (that it wasn't a big deal). I am going to try and recreate the brushwork though, to see if I can get fewer triangles out of the deal, because I have ~20 of these arches in my map. When they are not func_detail, they actually make more triangles, but to the naked eye it looks like less. I am just trying to learn all aspects of this stuff, and right now I'm working on a little optimization. I appreciate the knowledge brothers. I'll see what happens with -notjunc. OMG! It's everything I could dream of! Blueberry_pie, how could you know? I looked up -notjunc on google, and there's nothing! Beast.

08-09-2012, 10:22 AM	#6
ToMoBoBo Join Date: Nov 2009 Reputation: 0 Posts: 31	You are the man.