Upcoming Optimization to Collision Detection System - Beta Test on Mac Clients soon

Hi @Khanovich. My players are reporting same issues as during the last time when this was enabled - ships are getting flung by people walking on them, exactly like in my previous bug report. From the messages and videos I’m getting, the issues aren’t less severe at all.

This video robloxapp-20210330-1506068.wmv (2.9 MB) demonstrates the problem: a player in my game uses the teleport feature to board another player’s ship. When he starts to hit the walls, he causes the entire ship to flip and glitch out with a great force.

Could you please disable this update at least for my game? If you require another repro file, I’ll send one to you again. Thank you.

Meaning this feature isn’t enabled on the Server, so server logic is unaffected.

Hmm, I do need a repro file. When I was working with the one you originally sent me I was able to reproduce the issue regardless of flag state.

This is causing some weird bugs. First off, you can sometimes just straight up walk through parts that are 5 studs tall or less seemingly randomly.
There are ways to reproduce this, this place shows off one way that uses a ladder, read the description of the place for how to do it.
There is also a slightly harder but more abusable way of doing it by dancing then enabling shiftlock.

There are some other weird quirks such as sometimes walking into walls causes you to tilt like this:

Laugh clipping also became a LOT easier, you instantly go through the wall instead of ragdolling and hoping that you clip through the wall when getting up. This isn’t really that important but it’s just a strange side effect of this update.
New behavior (in a live game):

Old behavior (in studio) (you are able to clip through the wall if you get lucky I just couldn’t so I gave up):


I too am having the same clipping issues as @funwolf7.

I’m unable to tell you what the exact cause is b/c my game has a custom physics system and I can’t debug it in studio (where this isn’t enabled and works fine). However, when I “split” my character when pushed up against a wall I can walk through it.



I can provide a game file in DMs if you want/need one.


If possible, could you send me a simplified version of the game that isolates the logic of the humanoid split? (In a DM)

I want to do some testing to see exactly what happens here.


That game looks super cool is out yet and if it is can you send me a link so I can check it out

Yes i can! I’ll send it later today once I get rid of all the irrelevant stuff

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I’ve disabled it for now. There was an exploit discovered that should fix next week and I will re-enable for more feedback.


Next testing phase will be when 475 releases next week. I will first enable a Beta Feature on Studio to allow users to do more directed testing within Studio.


Beta feature has been added!

I will enable Windows and Mac testing tomorrow.


Enabled for Windows and Mac again.


The issues I posted before aren’t fixed yet. I think it should remain as a beta feature only until at least the ability to walk through walls that are short enough is fixed, if not the other issues as well.

You’re right, this was a hard issue to repro but I finally got it. Just got a fix! (Thanks to your game)

I won’t expand testing until this fix is out on production.

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This update has been absolutely devastating.

My game cannot function in this quasi-shipped state.

Not only is this new system riddled with issues where I can walk through geometry, but anything I do to fix it causes the old system to have issues allowing mobile players to walk through geometry.

I understand this has been long in the works, but this update has made it impossible for me to release my game and effectively made me waste months of my personal time.

I’m absolutely devestated by this update. Please turn it off until it’s fully fixed. This is ridiculous.


Can you elaborate? I thought we had a workaround where you can anchor/unanchor during the swaps to avoid this. Is this still related to the split game?

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This is still related to split.

On the new system I had users report a bug that allowed them to push themselves into geometry.

This can be done w/o the box (just ramming my upper half into my lower half), but it’s significantly easier to do with it.

I did find a fix for this by unanchoring and reanchoring the parts that’re bumping into me every heartbeat.

-- this solves the above issue on the new system
if physicsPart.Anchored then
	physicsPart.Anchored = false
	physicsPart.Anchored = true

However, when I run this fix in the old system (mobile) players can just run through everything!

As a side note: I don’t know if you saw it or not in our previous DMs, but I did create a significantly smaller like 80 line reproduction of my post on Apr 3rd.

I believe this is an entirely different issue though.


I’ve just disabled it, apologies for the pain. I’m keeping the Beta Feature on Studio enabled. When I ship a fix I will DM you before doing any global roll out.


Thank you very much!

I am working on a much smaller reproduction for today’s post. I’ll post it here when I get it.


@EgoMoose @funwolf7

Latest update of Studio as of this morning has a fix for the issues you reported. Can you check whether you can repro these issues with Accelerated Collision Pipeline beta feature enabled? (Make sure you have Studio 477)


All the issues seem to be fixed for me.