Shaky animation

Help & Support
1

Hi I have a project that when I’m viewing on my computer it’s stable but on mobile the animation becomes super shaky , any leads ?

here’s a build

2

Indeed I can confirm, on my Samsung Galaxy 10 the animation is quite shaky, even though the FPS is very stable and close to 60fps.

On desktop it works fine. Not sure why, is there anything special regarding the models/animations you use?

3

hmmm no I guess not, I mean the animation of the character is PLA baked from C4D and the camera is attached to a regular non baked fbx from c4d… ?

4

Invoking @slimbuck he may have some insight on this, I think there were discussion / change on how the animation speed is calculated on import time. Not sure if this is the issue here though.

5

ah wait I actually slowed the imported animation down to 0.3 can that have something to do with it ?

6

Sounds like this problem:

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7

Hi @will thanks for the reply!
however I don’t get what you mean by
“it should probably be updated to be done in the local space of the skinned mesh instance”

8

Currently, skinning is performed in world space. So as a skinned character moves further from the world-space origin, more numerical precision is lost when performing the skinning calculations. This causes vertex jittering on some devices (normally mobile GPUs). The solution here is to skin in local space somehow. I’ve assigned this item to @mvaligursky for investigation. It’s a long-standing issue.

9

So, for example, if I have a “climb on” animation that climbs up a wall, that the animation changes its position but the entity itself does not? Coincidentally, I was already wondering how I should do this…

10

Ah, that’s different from this problem. In your case, I would consider having the climb on animation as a transition and when it has finish playing, move the entity to the correct place on the wall and change to a climbing animation to match. It’s tricky to get right and there are a few different techniques.

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11

Ah okay. I will open a new topic about that later.

12

thanks for the replies however I am at a loss on this one. basically I would have to edit the original fbx?

13

Judging from Will’s reply, it’s a bug in our engine that one of our team will look at.

14

Would it be possible to upload a video of the shaking that you are getting in the animation @linelineline

15

This could be related to some phones not supporting 32bit floats in vertex shader. It seems at least some iOS models are like that.

Could you please try loading this:
https://webglfundamentals.org/webgl/webgl-precision-check-vertex-shader.html

it should confirm it highp is supported on a device, or if it only uses mediump

But it could also be related to GPU not supporting float textures, but only half textures. I’ll investigate in more detail soon.

16

On a Samsung Galaxy S10 which supports highhp precision, the animation is shaky.

17

@linelineline - are you able to add me to your project? user name mvaligursky

18

I have a PR which solves separate ticket with shaky animation on iOS device I’m testing on (iPhone XR)

@linelineline - if you could give me an access to your project, I could test it before this gets released.

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19

hi @mvaligursky,
sorry the late reply, Im currently using the project for a testing the next months so I wont edit it again till then. but thanks I will most definitely get back to it!

1 Like