Collsion prims

repete · Mar 2014

Hello all,

How does UDK arrive at the collision calculation below, it has me baffled:

and the collision mesh:

I am getting 76 collision prims with this mesh and I need the bend in it. Can anyone explain to me what UDK does to the collision mesh and would it better to cut the collision mesh up into lets say 2 parts ?

thanks
pete

Obscura · Mar 2014

I'm not sure, but maybe your mesh has "bad" transformations. Have you tried reseting xform? Per poly collision as an alternative?

repete · Mar 2014

Thanks Obscura

Definitely something wrong and I think it's coming from modo. I am just using the thicken tool to get the UCX mesh and removing loops but I cannot select the new polys created by the thicken tool in modo which is odd behaviour. I think this is messing up the mesh.

Obscura · Mar 2014

Here you go with the per poly collision which can be set inside udk. I think it will work fine cause your mesh is fairly lowpoly: double click to your asset in the content browser, uncheck all the collision related properties. Then select your mesh in the viewport, f4, search the collision related section, and check "collide complex".This is really a timesaver solution, and works really good. Or, you can create a collision mesh with the builder brush (BSP).

repete · Mar 2014

the per poly collision works but this is part of a modular tunnel system and when the player collides with the sides of the tunnel game play gets jittery and I think this is a draw back with per poly collision as it's not present with the UCX collision.

I have had zero issues with straight modular segments but now there is a bend and the collision is going haywire. Looks like some polys are being double triangulated so modo is probably the culprit !

bloody frustrating :poly127:

WarrenM · Mar 2014

If that IS the collision mesh you're trying to import above, that's going to bring nothing but pain because collision primitives have to be convex. If they aren't, I think UDK tries to break them down for you and that is almost always messier than just doing it yourself in your modeling app.

Something like a bending tunnel is definitely going to be better off with per-poly collision if it's low poly enough. Otherwise, you're going to have a TON of individual primitives and that's going to be just as expensive.

repete · Mar 2014

per poly collision causes bad jittery game play inside the tunnels. I have done some basic sculpting in mudbox to make the cylinders look like natural tunnels (caused by flowing water) so I did have to up the polycount a bit to add the extra detail.

Using the bend and slice tool in modo I managed to sort the collision out without prims, the cylinder in the pic below also slops upwards and bends to the right so it was a bit of a pain. No prims this time !!!

I guess patience is a virtue :poly121:

Collsion prims

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