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Won't Fix

Votes

12

Found in

2021.3.36f1

2022.3.20f1

2023.2.13f1

2023.3.0b10

6000.0.0b11

Issue ID

UUM-65366

Regression

Yes

A 1000 times heavier GameObject will stutter when colliding with a lighter GameObject

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How to reproduce:
1. Open the “HeavyObjectBug.zip“ project
2. Open the “TestScene“
3. Enter Play Mode
4. Observe the Game view

Expected results: The heavy GameObject does not stutter on collision with light GameObjects
Actual results: the heavy GameObject stutters on collision with light GameObjects

Reproducible in: 2021.3.30f1, 2021.3.36f1, 2022.3.8f1, 2022.3.20f1, 2023.2.13f1, 2023.3.0b10
Not reproducible in: 2021.3.29f1, 2022.3.7f1

Reproduced on: Windows 11 Pro (23H2)
Not reproduced on: No other environment tested

Note: The issue is very visible when the “CubeLight“ GameObjects have a mass of 1, and the “SphereHeavy“ GameObject has a mass of 1000

  1. Resolution Note:

    We have decided not to address this issue at this moment. The mass ratio is outside of what can be expected reliable simulation from. Also, from a theoretical perspective both behaviours (pre-change, and after change) are incorrect: before the change the large body would pierce through the small one and only accidentally drag it together at around exit from collision, after the change it won't pierce through but there might be arguably questionable reciprocal motion. It's a consequence of an otherwise good change that addressed CCD objects tunnelling in certain conditions. We might reconsider this resolution later.

Comments (3)

  1. fortnairobi

    Jun 02, 2024 07:22

    if you say the n word your band

  2. omersimchonimusic

    May 18, 2024 09:47

    I'm not sure where to begin - whether the fact that this is just a symptom of a much more severe bug that has HUGE impact on physics behavior, or the fact that it's still being perceived as a small thing, another bug out of many.
    In my case, I'm developing a ball game. The ball hit a wall and should change its angular velocity due to friction effect.
    Surprisengly however, when upgrading to 2022 LTS, the ball just stopped being affected by friction randomly.

    I understand that the goal is to make the physics more realistic, however I don't remember playing tennis and the ball just "skips" the friction effect occasionally and randomly. Well, unless playing on ice.

    Pls take this seriously. I've spent a week trying to figure out a workaround and moving between different Unity versions and 3rd party packages versions.

  3. PandaArcade

    Mar 02, 2024 01:59

    In my tests, the issue is present even when the mass ratio is 1:1. Check out my latest forum post for a video illustrating the issue with various mass ratios.

    https://forum.unity.com/threads/physics-performance-regression-in-unity-2022-3-8-and-onwards.1495442/#post-9675257

    Won't Fix - is unacceptable!

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