[OB] Creature collision mesh problems

[syscrusher]

I am trying to use some custom-created creatures from a modders' resource (specifically, BT More Enemies) in my quest mod. I was able to import them, and they animate just fine, process their AIs, enter combat, and so on. The problem is that when they are killed, they sink through the floor of the dungeon, or through the landscape mesh if outdoors!

I looked at the BSX flags in the NIF, and compared the collision mesh to that of other creatures from the same resource that *don't* have the problem, and I can't see any differences.

Has anyone seen behavior like this before, and if so, what should I be looking at other than just the BSX flags?

Thanks!

(Edit: Sorry, I realized I forgot to prefix the subject.)

Edited October 29, 2012 by syscrusher

[syscrusher]

I've replicated this problem in another area, and I think I have an additional clue. The creatures are actually not just dropping through the floor. What's happening is that they "stretch" to negative infinity in the Z axis. I saw behavior similar to this with vanilla beast races, if you happened to create an Argonian with skeleton.nif instead of skeletonbeast.nif. The error was caused by geometry that was skinned to a bone (the tail) that didn't exist in the non-beast skeleton.

I'm trying to work out a scripted way around this, perhaps disabling the dead creature and replacing its corpse with a non-animated container version of the mesh, but I wonder if someone else has seen this before, and perhaps has a fix? The creatures in question are the worms from BTMoreEnemies. The README from that mod indicates that the scorpion has this as a known bug, but only for interior cells. I have observed the same problem with the worms, and again, only for interior cells. I'm just curious what could be different about collision behavior interior vs. exterior, and whether that is a clue to the root cause.

Thanks for any help.

[syscrusher]

I have a further clue, and a big one: I have replicated the problem under controlled conditions in the Construction Set. If you run the Havok simulation on a worm with zero health (that is, a pre-killed creature), the various segments of the body move independently, and can either separate or pile on top of each other just as if they were separate objects. The skin, of course, stretches to accommodate, even to ridiculous geometry.

I think what's going on here is that some of the skeleton bones are not properly connected or constrained. While I know how to animate objects like platforms and drawbridges, I'm afraid I don't know enough about creature animation to fix this.