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mmchickenshack
Up and Coming
July 28, 2019

Moving Grabbed Objects jitter (Unity)

  • July 28, 2019
  • 19 replies
  • 12256 views
Using Unity 2018.4.5 and Oculus 1.38

When I hold an object (simple scene with just a cube) in my hand, then the movement of this grabbed cube is very jittery and not smooth at all.

Using OVRPlayerController with LocalAvatar in TrackingSpace and AvatarGrabberLeft and Right inside this LocalAvatar.
I set the Fixed TimeStep in the Project Settings to 1/72 (0.01388889).

I uploaded a video of this behaviour: https://youtu.be/AoJ_d0d2Dq8

It's not as obvious in the video as it is in VR, but I think you do see the issue at the edges of the cube with the stuttery movement.
Interestingly, when I throw away the cube, the movement is smooth. Also the movement of my hands is smooth, it's only the object I'm grabbing that stutters.

Any idea how I can prevent this?
Thanks!


19 replies

mmchickenshackAuthor
Up and Coming
July 30, 2019
Update: I have the same problem with the demos that oculus provides. seems to be a unity/sdk issue. as you know, version 1.39 is broken in other ways, so i couldn‘t test if this resolves the issue...
very unsatisfying situation.
cibernaio
Up and Coming
February 8, 2023

Do you know after so long if a solution has been found?

lamhoang
New Participant
July 30, 2019
Add some of your own code, which makes the object your grabbing the child of the grabbing hand. This will remove the jittering.
    mmchickenshackAuthor
    Up and Coming
    July 31, 2019
    thank you, that absolutely worked. I found an even easier workaround:

    The solution was to child the hands (in my case Oculus' "CustomHandLeft/Right") to Left- and Righthand-Anchors respectively. Smooth as butter now, even in Unity 2019: https://imgur.com/a/PnTXbOq

    Thanks for your time and help!

      Hamidoo
      New Participant
      March 25, 2025

      this absolutaly helped reducing the jitter and shakiness. Thanks. Meta is so dumb for not making that by default. 

      TraverseMorcant
      Participant
      August 1, 2019
      @mmchickenshack I am experiencing the same issue when using LocalAvatar and AvatarGrabberLeft/Right. Adding them as children to the anchors makes the grab not work. Can you provide more info on how you fixed it?
      mmchickenshackAuthor
      Up and Coming
      August 1, 2019
      @WolfVolk I think I had the same issue a while ago. Try using the CustomHands, they seem to work better for me.
      mmchickenshackAuthor
      Up and Coming
      August 1, 2019
      @WolfVolk also, uncheck "Parent Held Object" (that broke grabbing for me as far as i can remember) and make sure the parent transform is set correctly.
      vrzdev
      Up and Coming
      August 4, 2019
      @mmchickenshack - having the same problem with AvatarGrabberLeftRight as @WolfVolk. "Parent Held Object" is unchecked and the grab is not working. What should I set as Parent Transform?

      vrzdev
      Up and Coming
      August 4, 2019
      Ok i set the parent transform to TrackingSpace and the grab is back to work, but the hands movement are still jittery.

      vrzdev
      Up and Coming
      August 4, 2019
      I found out that if you check "Parent Held Transform" on both AvatarGrabberLeft/Right, the object stops jittering while grabbed. Unfortunately this also produced a strange misalignment of the hands while moving them around.
      mmchickenshackAuthor
      Up and Coming
      August 5, 2019
      i‘ve opted to use vrtk 4 now which has none of these problems. it‘s a bit harder to get into, but once it works, it just works. the oculus integration just seems buggy as hell at the moment.
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