Why do collisions fail on moving meshes?

Hi all.

I don’t know if this is a bug or just a feature which isn’t supported in Unreal, but I desperately need for collisions to work on a moving mesh - specifically if you are standing in front of the space which the animated mesh is just about to occupy. From what I can see the collision seems to be completely absent all the time the object is moving - but, even worse, returns just as soon as it stops moving - trapping the player inside the mesh.

I enclose some sample frame captures of the character standing inside a wheel object which moves on a 3 second pulse (shifting to the next position for a second and a half then holding there for the same duration). As you can see the character is wholly absorbed into the mesh to the extent of dangling without gravity for a few seconds. (The character has render custom depth so that you can see him through the mesh)

I suppose this question might additionally be rephrased as “how do you get an animated static mesh (i.e. platform, wheel, etc.) to push the player out of the way?”, but I have seen that question asked on a couple of occasions, with no satisfying answer - and in my case the mesh moving the character is incidental to what I want (I’m not trying to make a car crusher - or whatever - I just want my game to NOT be broken). There are so, so many occasions when this might prove a problem in a game - I can see players getting caught in doors, jammed in moving platforms dangling over lava pits, etc. This is a real problem.

Does anyone possibly know if Epic has plans to fix this? or if there are any workarounds?

Hi graemevaughey,

Which version of the editor are you currently using? Also, are you moving the mesh through Matinee or blueprints?

Thanks for the reply. I’m using the latest version of the Engine. I’m currently using Matinee for the movement of the wheel, though I read on another forum post that blueprint scripted motion works in a different way for collisions and have tried that also, with the exact same results.

I’ve just found a very apt description for exactly the problem I’m having in another post: Collision not working when standing still? - World Creation - Epic Developer Community Forums
While I’ve yet to test the solution given on this page, skimming through it, it seems like a feasible fix for now, but I would obviously prefer an actual fix in the engine for what I can imagine will be a frequent problem for nearly every user at some point in their development. This original post was from May/June: do you know if we are anywhere close to getting a fix for this in the editor soon?

I have been testing this in 4.4.3 and it’s working for me in-house. Would you mind posting your .uasset for the mesh that you are using?