SkeletonAnimation exists, but Skeleton is null (Unity 6.2, Spine 4.2)

DateSayurin

Hi,
I’m a bit confused about how SkeletonAnimation initialization works in Spine-Unity.
I’m using Unity 6.2 with Spine 4.2.
I can successfully get the SkeletonAnimation component:

sa itself is not null, and the skeleton renders and plays animations correctly in the scene.

However, when I try to access the skeleton:

it’s always null at runtime.

Because of this, I can’t do things like:

sa.Skeleton.FindSlot("state");

even though the documentation says SkeletonAnimation.Skeleton should give access to slots, bones, etc.

Some extra context:

I’m not using SkeletonGraphic, only SkeletonAnimation

I want to get a slot and modify its color at runtime (e.g. focus / highlight)

SkeletonAnimation exists and works visually, but Skeleton is null when accessed

I’m currently trying this in Awake() (and also tested Start() with the same result)

Where could the issue be?

Misaki

DateSayurin First, we sincerely apologize for the inconvenience caused by the forum system error. The issue has now been resolved, and we have merged your duplicate threads into a single post.

Regarding your question, I was unable to reproduce the issue using the same version combination (Unity 6.2 with Spine 4.2). The code I tested is as follows:

using System.Collections;
using UnityEngine;
using Spine;
using Spine.Unity;
public class ChangeSlotColor : MonoBehaviour
{
    SkeletonAnimation sa;
    public Skeleton skeleton;

    void Awake()
    {
        sa = GetComponent<SkeletonAnimation>();
        sa.Initialize(true);
	skeleton = sa.Skeleton;

        var slot = sa.Skeleton.FindSlot("head");
        slot.SetColor(new Color(1, 0, 0, 1));
    }
}

Here is the video recording of the test results for your reference:

If the issue persists on your end, could you please email us a minimal Unity project that reproduces the problem?: 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.

DateSayurin

I’m a bit confused about how SkeletonAnimation initialization works in Spine-Unity. I’m using Unity 6.2 with Spine 4.2, and I can successfully obtain the SkeletonAnimation component itself—sa is not null, and the skeleton renders and plays animations correctly in the scene.

However, when I try to access sa.Skeleton at runtime, it is always null. Because of this, I can’t do things like sa.Skeleton.FindSlot("state"), even though the documentation states that SkeletonAnimation.Skeleton should provide access to slots, bones, and other runtime data. For additional context, I’m not using SkeletonGraphic, only SkeletonAnimation, and my goal is to retrieve a slot and modify its color at runtime (for example, to implement a focus or highlight effect). Visually, SkeletonAnimation exists and works as expected, but the Skeleton reference is null when accessed from code. I’ve tried accessing it in both Awake() and Start(), but the result is the same in both cases. Where could the issue be?

Also, I’m not sure why I can’t access or view my previous post, so I’m reposting this here. ww

DateSayurin

Misaki

I’m not sure whether this was related to the Spine runtime or Unity itself. At the time, I had kept the project open for several days without restarting, and during that period I really couldn’t get the Skeleton at all.
After restarting the project, it started working correctly. That said, even now when debugging, Skeleton still sometimes shows up as null in the debugger, even though it actually has a value and I can successfully access the corresponding slots.

In any case, from a functional point of view everything is working normally now, so it’s probably fine www

Misaki

DateSayurin Good to hear the issue seems to be resolved for now!
I'm also not sure what caused your problem, but our Unity expert, Harald, might be able to offer additional advice when he returns from vacation.

Harald

@DateSayurin Sorry for the late reply, glad to hear it was resolved after re-opening Unity. It's a bit hard to diagnose the cause of such issues. The issue might be related to the debugger and accessing the SkeletonAnimation.Skeleton property, which itself calls Initialize(false); before returning SkeletonAnimation.skeleton here.

In general I would recommend to not have the property SkeletonRenderer.Skeleton open in any watch window in the debugger, to avoid undesired debugger side-effects. Instead you can directly access lowercase .skeleton in the debugger.

Harald

@DateSayurin Sorry, I think I was wrong in my previous posting. I just remembered encountering this or a very similar issue in the past where the combination of
[System.NonSerialized] public led to the problem. Unfortunately I could not reproduce the same situation now, so there is no guarantee I remembered it correctly. Anyway, it should only affect the displayed fields in the debugger and not the actual game or the build.