If you set up a collision group to ignore collisions between player characters, and then have two characters stand on top of a moving platform inside of each other, they will gradually slide off the platform for seemingly no reason. This only seems to happen when they are standing very close/inside each other, because otherwise they just move with the platform as expected.
Here’s a video of it occurring:
This is a little annoying because I have a section of my game that puts players very close together on a moving platform, and this can cause players to unfairly fall off.
Expected behavior
What should happen is that the humanoids should completely ignore each other, and not cause them to slide off the platform like this. When they aren’t standing close to each other, they move along with the platform perfectly.
Hi there! Thanks for the report, we’re still taking a look at this issue. The only update so far I can say is that this is probably more of a humanoid issue than a collision groups one. If you replace the humanoids with simple parts that have collision groups set to not collide, you won’t see any of the sliding you’ve seen. Unfortunately we can’t guarantee any fixes in the immediate future, but we’ll do our best.
Any workaround depends on the constraints of your game – I’d suggest at the very least trying to avoid spawning characters at the same location, or potentially adding barriers to the platform?
Otherwise we’ll keep you updated on any fixes!
Thanks for replying. Unfortunately barriers do not prevent humanoids from sliding off, they will still just phase through it, which is the most annoying part as I’m sure you can imagine. There was a workaround found where you can manually toggle off CanCollide on the other player’s characters on the client-side, and it solved the issue for the most part, but I’m still having trouble with it.
My final(ish) solution was to just not use physics at all. I’m now CFraming the platform and I wrote some code to update the player’s position each heartbeat according to the platform’s movement, and interpolating other player characters so they don’t appear to trail behind due to latency.
We don’t have any updates at this time, but will be sure to follow up on this thread when we have a fix / any relevant information to share. Thanks for your patience!
Hello, we’ve identified and fixed a bug with humanoid code that wasn’t properly respecting collision groups. The repro you’ve attached should now be fixed. Let us know if you encounter any other issues!
