Incorrect Constraint Solving on Mobile

Bug Reports Engine Bugs
#1

Reproduction Steps
This issue occurs on both iOS and Android. It was first reported to me around 12 PM PDT today. Simply use any vehicle using the “A-Tune” chassis to reproduce the issue. This issue may be more widespread than what I have seen reported. Seems to happen when network ownership of the vehicle (thus also its constraints) is given to a mobile player.

Video taken from iOS:
https://cdn.discordapp.com/attachments/598600200084258822/964255367905308733/RPReplay_Final1649966767.mp4

Video taken from PC showing contrast between PC and Android:

Expected Behavior
I expect constraint solving to be uniform across PC and mobile, regardless of which platform currently “owns” the mechanism.

Actual Behavior
Constraints are incorrectly solved on mobile.

Issue Area: Engine
Issue Type: Other
Impact: High
Frequency: Constantly
Date First Experienced: 2022-04-14 12:04:00 (-07:00)
Date Last Experienced: 2022-04-14 00:04:00 (-07:00)

8 Likes
#2

Support on this. Same for Car Dealership Tycoon.

1 Like
#3

We’re experiencing similar issues for our players in Emergency Response:Liberty County. Started occurring roughly a few hours ago. Noticed mainly tablet reports.

4 Likes
#4

Similar is happening to our experience: Greenville - Roblox

1 Like
#5

Pretty much at the same time issues have started with tables, mainly slowdowns (My particle system broke and a friends backrooms generator slowed drastically)

I wonder if A-Tune uses any tables (Specifically large tables)

1 Like
#6

Happens inside of Pacifico 2: Playground Town and Driving Empire.

I’ve made a probable relations section in my post on a related topic here but at this point I think it’s pretty big. Critical impact at this point probably.

2 Likes
#7

Also experiencing this in my game Canterbury & District Bus Simulator V4.1, This issue is quite heavily impacting the game causing vehicles to glitch out and fling.

2 Likes
#8

Thanks for reporting this issue, we are investigating now!

3 Likes
#9

This issue was related to improper handling of hinge constraint limits, we have reverted a flag that caused this issue. Thank you all for the help identifying the issue, please reply in this thread if you continue to see incorrect behavior.

8 Likes
#10

I am currently having this issue on one of my games when a tablet user enters a locomotive or car the wheels spaz out causing the vehicle to fling all over the place

#11

This could be a result of stale flag values. Could you please check the status of the flags SimSolverCacheForces and SimSolverInsideOfSphereZeroRadius? You can check flag values in Studio by going to File->Advanced->Open Flag Editor.

#12