Animator state is reset when AnimationClips are replaced using an AnimatorControllerOverride

August 03, 2021 15:45
Updated

Symptoms

The state of the Animator gets reset when you change the AnimatorControllerClips at runtime.
When you try to change the AnimationClip, it does not work the second time that is changed.

Cause

It is expected that the Animator is reset when you change a clip. Unity needs to save the Animator state before replacing the AnimationClip and set it back after it has been replaced, but that feature is not implemented in some versions of Unity.

Resolution

As a workaround, you can use scripting to save and restore the state of the Animator when changing the AnimationClip.

void ChangeClip(AnimationClip clip ){
    Animator anim = GetComponent<Animator>(); 
    AnimatorOverrideController overrideController = 
        new AnimatorOverrideController();

    AnimatorStateInfo[] layerInfo = new AnimatorStateInfo[anim.layerCount];
    for (int i = 0; i < anim.layerCount; i++)
    {
        layerInfo[i] = anim.GetCurrentAnimatorStateInfo(i);
    }

    overrideController.runtimeAnimatorController = anim.runtimeAnimatorController;
    overrideController[currentClipName] = clip;
    anim.runtimeAnimatorController = overrideController;

    // Force an update
    anim.Update(0.0f);

    // Push back state
    for (int i = 0; i < anim.layerCount; i++)
    {
        anim.Play(layerInfo[i].fullPathHash, i, layerInfo[i].normalizedTime);
    }
    currentClipName = clip.name;
}

More Information
 
Please also see this Forum Swapping Override Clips at Runtime.
 
This article applies to Unity version 5.1.1f1 and higher

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