Jittering movement [not on all computers]

Unity Engine
,
1

Hello guys,

while my game works fine on most other machines, it stutters alot for one of my testers and I don’t know why.
I made a comparison video below, it’s clear to see which videos comes from me and which from the tester:

Since this ship uses a Rigidbody, I placed all movement-related controls inside FixedUpdate(). The script is attached to the Ship GameObject.
All Methods necessary for the camera to follow the ship are in LateUpdate(), script attached to the camera.

The jittering problem remains across all quality settings. I am unable to reproduce this behaviour on any other computer.
Those are the specs of the computer with the problem:
CPU: Intel i7-X7820X@3.60 GHz
GPU: EVGA NVIDIA GTX 1080Ti
RAM: 32 GB DDR4@3.200MHz

Any idea what could cause this behaviour?

2

Is interpolation enabled for all rigidbodies? It generally should be. This is the most common reason for stuttery motion in Unity by a long shot.

Otherwise things like vsync on and just being at the threshold between 30 and 60 can cause it (vsync will lock the frame at either 30 or 60, causing a stutter). Seems unlikely though given it’s stuttering is very regular.

What version of Unity?
Some versions have crappy physics bugs.

3

Thanks for your reply.

Unity version 5.6.2

Ships Rigidbody is set to Interpolate. The camera also has a Rigidbody, the Interpolation is set to “None” there.
The camera has it’s Rigidbody set to Kinematic while following the ship. It can however detach from the ship and needs Rigidbody behaviour by then. Then I disable Kinematic.
During the following of the ship however, the Camera stays Kinematic.

Could there be a problem with this?

4

I would suggest making a copy of your project and upgrading it to 2017.3 and trying that on your tester’s computer. If the problem goes away, it was likely a newer bugfix. If the problem remains we’ll have dig a bit deeper.

If you like you can also try 5.6.4 p4 which is in the 5.6 feature set if you’d prefer to stay with 5.6 - in short it might be any number of bugs but we probably should eliminate Unity being the source of it.

5

Alright, thanks alot!

Right now I made sure that also the camera RB is interpolating. I let my friend test it and if it didn’t help, I’ll upgrate Unity and test again.

In any case, I will report what fixed the problem or if the problem remains.

Thanks again for your help so far. Very appreciated :slight_smile:

6

Ok, an update:

  • Setting Interpolation on camera did not fix the issue
  • Using AntiAliasing made the issue a bit worse
  • Unity and project is now updated to 2017.3.0p1. The issue remains although there are sometimes smooth moments, only lasting less than a second, though.

I have another friend who tested it, he also has the GTX1080, just not the Ti version. Runs smooth there.

7

Just a guess here, do you have wait for vsync turned on? If so it could be one computer is faster than the other and can keep up the frame rate while the other is struggling and keeps missing the vsync so waits for an extra frame.

8

Good guess. I currently had “Every V blank” set to all quality settings. I’ll give it a go with all options available and see if there is a difference!

Will report back.