I have insane flickering issues of spine animation in unity.

BBbummo_OMB · 10 Th01

Hello,

Recently on my unity project, a weird flickering issue started to occur on my spine animation.
Below video shows the issue.

Assertion failed on expression: 'IsFinite(distanceForSort)'

Here are some information about my project:

flickering occured when I upgraded spine-unity runtime to latest version
other than flickering, there were some issues about not-visible slot attachments on the previous spine-unity runtime. This was the reason I upgraded the runtime to latest one.
spine: v 4.2.38
uses physics constraint, IK constraint, transform constraint
does not have skin
player character and mimic character uses same spine skeleton data
player character and mimic character uses same animation player script
player character has no issue on idle, move, jump, ... animations
mimic character has serious flickering issue on idle animation(other animation seems to be fine)

I assumed the export error at first, so I tried almost every possible export options I could, but it seemed to fail. When flickering occured, following error messages were on the debug console:

Invalid worldAABB. Object is too large or too far away from the origin.

Mesh 'Skeleton Mesh': abnormal mesh bounds - most likely it has some invalid vertices (+/-inifinity or NANs) due to errors exporting. Mesh bounds min=(-2783052908462080.00, -572092753246083350528.00, 0.00), max=(6150273445658624.00, 258876969311673516032.00, 0.00). Please make sure the mesh is exported without any errors. UnityEngine.GUIUtility: ProcessEvent (int,intptr,bool&)

In order to call GetTransformInfoExpectUpToDate, RendererUpdateManager.UpdateAll must be called first.
UnityEngine.GUIUtility: ProcessEvent (int,intptr,bool&)

I searched on the forum, and found a similar discussion:
https://ko.esotericsoftware.com/forum/d/23928-mesh-skeleton-mesh-abnormal-mesh-bounds
But as i mentioned, this possibly happend when I updated the runtime.

Any kind of solution or help would be sincerely appreciated.
Thank you.

Spinebot · 10 Th01

The flickering issue you're experiencing with your Spine animation in Unity seems to be related to numerical precision problems, especially given the error messages about invalid world AABB and abnormal mesh bounds. This can occur when the mesh vertices have extreme values, possibly due to constraints or transformations applied in your Spine project. The error messages suggest that the mesh might have invalid vertices, which could be caused by the constraints or the way the skeleton is set up.

To address this, you can try the following steps:

Check Constraints: Review the constraints (physics, IK, transform) in your Spine project to ensure they are not causing extreme transformations. You might want to simplify or adjust these constraints to see if it resolves the issue.
Export Settings: Double-check your export settings in Spine to ensure they are correct and compatible with the version of the spine-unity runtime you are using. Sometimes, mismatched settings can lead to such issues.
Update and Test: Ensure you are using the latest versions of both the Spine editor and the spine-unity runtime. If you are already on the latest version, consider testing with a slightly older version to see if the issue persists.
Debugging: Use the Skeleton Viewer to inspect the skeleton and animations outside of Unity. This can help identify if the issue is with the export or the Unity integration.
Minimal Project: If possible, create a minimal Unity project with just the problematic animation and skeleton. This can help isolate the issue and make it easier to debug.

If these steps do not resolve the issue, it might be helpful to look into the specific constraints and transformations applied to the mimic character, as the player character does not exhibit the same problem.

BBbummo_OMB · 11 Th01

Here's some more additional problems regarding this issue.

I assumed that there might be a corruption or error on the spine export itself, so I created a new project, put every attachments on the project, and went straight to the export, and an error message came out.

An error occurred while packing the images.
Error: Copying 0,0 (62x109) to 783,-1 (2033x612).
Error: ArrayIndexOutOfBoundsException

I also tried with exporting ONLY ONE sprite. And same error occured.

I didn't had this error on the previously existed project, but this occurred when I tried an export on the new project. Maybe solving this packing issue might also solve the problem above?

Misaki · 12 Th01

Bbummo_OMB I'm sorry to hear you're having trouble. It's hard to figure out the cause just from that screenshot, so could you please send us via email the Spine project where the error occurs?: contact@esotericsoftware.com
Please include the URL of this forum thread in the email so we know the context. Then we can take a look at what's wrong.

BBbummo_OMB · 12 Th01

Misaki
Thank you for cheking the issue. I've just sent an email including things you asked.

Misaki · 13 Th01

Bbummo_OMB Thanks for sending us the Spine project files! I checked and exported them with the texture packer settings exactly as they are saved in the project, but I was not able to reproduce the error you show in the screenshot you showed. By the way, I was wondering a little bit why this texture is packed with a padding of 100 pixels?:

The default value for the padding setting is 2, so 100 is quite large. After I did the first export with the saved settings, I reset to the default settings and did the export again, but no errors occurred in either case. I'm not sure if the value of this padding setting has any effect on the flickering issue, but I think it might be involved in the packing error.

As far as importing the exported skeleton files into a new Unity project, I could not reproduce the flickering problem, so could you send us a minimal Unity project that can reproduce the problem?: contact@esotericsoftware.com

BBbummo_OMB · 13 Th01

Misaki
Thank you again. I've just sent another email about the things you asked.

Speaking of padding, I made the padding extremely large as I wanted to make some shader override to make some vfx effects on the character(it needed some spaces...). I also assumed this as the main reason of error, so I reduced the margin and exported - still issues occured. So I think padding size is not the cause of this issue...

Misaki · 13 Th01

Bbummo_OMB Thank you for sending us the Unitypackage file. I have tried to check it, but various errors prevented us from doing so immediately. Could you please prepare a project in a more minimal state? Ideally, we would like you to create a new Unity project, import your skeleton, reproduce the problem with your skeleton, and send the project files to us.

I understand about the padding, but does that mean you can still reproduce the error? I was not able to reproduce the problem on my end, so I would appreciate it if you could share the detailed reproduction method here as well.

BBbummo_OMB · 14 Th01

Misaki
Hello, thank you for your hard work.

Unfortunately, my project seems to use quite complicated stuff, so it might be very difficult and time-consuming to create another minimal project. Also, as I spent too much time on this issue, I cannot wait another day to get solutions.

So I decided to do a rework on my spine animation. I'll make a similar form of spine animation from the start. I'll try making these at the latest state(spine, runtime, ...) and try importing them on my Unity project. After the reimport, if the same thing occurs again, I'll ask for your help.

Still, I do appreciate that you tried to help me. Thank you.

Misaki · 14 Th01

Bbummo_OMB I understand, thank you for taking the time to explain your situation. I apologize for not being able to provide you with a clear solution, but if you have any further questions or are at a loss, please do not hesitate to contact us.

BBbummo_OMB · 15 Th01

Misaki
I found the cause and solved the problem.

I made a weakness point on my spine-controlling script that could allow the skeleton.ScaleX value into 0. I debugged the project by printing the skeleton.ScaleX values, and found out that flickering graphic and squished spine animation occurred when this value was set to 0. I added an if statement so that skeleton.ScaleX could be set either -1 or 1, and the issue was gone.

So there were no bug or mistake on the Spine from the beginning. If anyone is having similar issue, please try checking the skeleton.ScaleX or skeleton.ScaleY value first.

PROBLEM SOLVED!