Collision mesh advice

Quillisia · Jun 2010

Hey guys. What is the best way to create a collision mesh for a shape like this? It will be used as a walkable platform and the player should be able to fall off.

I am not sure how to keep the shape convex without having a large number of seperate segments. Any tips?

Xoliul · Jun 2010

Is it gonna be static? If so, just use the mesh itself as collision, works fine.

Quillisia · Jun 2010

Yes it will be. I was always under the impression using the mesh itself was not a good idea. Glad to know thats not the case. Thanks Xoliul!

gamedev · Jun 2010

Using the mesh on simple things is ok. More complicated geometry though, it's not a good idea.

If you find yourself making more than a few collision primitives for a mesh, you should re-consider how it's built. In particular, your ring could be broken up into a few modular chunks, each with a few collision primitives each.

You can get away w/ pretty low detail collision most of the time as well. More detailed collision can usually mean people get caught up on things.

Cheers,

TYler

Xoliul · Jun 2010

To my experience even complex models run fine with mesh collision, gamedev. PhysX does a nice job optimizing the perofrmance on those things.

JordanW · Jun 2010

using the mesh as collision is very bad. Yeah it may work fine in a small level but on a real production scale it's a bad idea. Collision primitives should be as simple as possible. I would maybe try to match that ring as closely as possible but maybe skip every other edge or something. Remember to keep it convex.

Quillisia · Jun 2010

If I were to do that Jordan, I would still have around 14 separate segments. Would this be an acceptable number?

Xendance · Jun 2010

You should probably check out some Epic made assets in the UDK, just an idea

JordanW · Jun 2010

It all depends but if that's what it takes to make the collision for that mesh then yes.

Snight · Jun 2010

Jordan and Gamedev are right. Ideally you would want to separate that mesh into modular chunks anyway for a number of reasons. You'd only have to do like 2-3 seperate pieces.

Quillisia · Jun 2010

Thanks for the help guys!

dn-revenge · Jun 2010

http://www.chrisalbeluhn.com/UT3_Asset_Creation.html scroll down a bit...for this pic and more useful info on collision ..

one of the rules of collisions

Xoliul · Jun 2010

JordanW wrote: »

using the mesh as collision is very bad. Yeah it may work fine in a small level but on a real production scale it's a bad idea. Collision primitives should be as simple as possible. I would maybe try to match that ring as closely as possible but maybe skip every other edge or something. Remember to keep it convex.

Well hmm, I worked in a company where it was used on production scale. The tech artist kept telling me it was fine to do it like that, and the programmers never complained about performance problems. What is the reason you shouldn't use mesh collision ?

Collision mesh advice

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