Activating GameObjects from the animation clip

Unity Engine
1

I want to use an EditorWindow to create animation curves that will activate my hitboxes at the correct time.

When adding manually a hitbox in my animation clip. I can see its type among other things: UnityEngine.GameObject

So I coded this:

EditorCurveBinding bind = new EditorCurveBinding();
bind.type = typeof(UnityEngine.GameObject);
bind.propertyName = "m_IsActive";
bind.path = "Hitboxes/" + hitbox.name;

var keys = new List<ObjectReferenceKeyframe>();

var keyOn = new ObjectReferenceKeyframe();
keyOn.value = hitbox.gameObject;
keyOn.time = 0f;

keys.Add(keyOn);

AnimationUtility.SetObjectReferenceCurve(anim, bind, keys.ToArray());

I get the following error because of AnimationUtility.SetObjectReferenceCurve:
“Can’t assign curve because the type does not inherit from component”. (Imgur: The magic of the Internet)

Indeed, typeof(GameObject) doesn’t inherit from Component, but what can I do to make this work? Logically this should be possible since it can be done manually.

2

I found the solution:

private void AddAnimationCurveAccordingToHitboxNames()
    {
        var spriteBind = new EditorCurveBinding();
        spriteBind.type = typeof(SpriteRenderer);
        spriteBind.propertyName = "m_Sprite";

        foreach (var hitbox in Hitboxes)
        {
            var goBinding = new EditorCurveBinding();
            goBinding.type = typeof(GameObject);
            goBinding.propertyName = "m_IsActive";
            goBinding.path = "Hitboxes/" + hitbox.name;

           
            foreach (var anim in AnimationClips)
            {
                var frameTime = 1 / anim.frameRate;

                var sprites = AnimationUtility.GetObjectReferenceCurve(anim, spriteBind);

                // find the sprites that are named correctly and their time
                foreach (var s in sprites)
                {
                    var val = s.value;
                    var time = s.time;

                    var spriteName = FindNameWithoutTagWithoutVersion(val.name, true);

                    // TODO: This only works if there's 1 same sprite name per animation? Do we care?
                    // TODO: What if the hitbox is the last frame, it doesn't get deactivated
                    if (spriteName == hitbox.name)
                    {
                        var curve = new AnimationCurve();

                        var keyBefore = new Keyframe();
                        keyBefore.value = 0;
                        keyBefore.time = time - frameTime;

                        var keyAfter = new Keyframe();
                        keyAfter.value = 0;
                        keyAfter.time = time + frameTime;

                        var keyOn = new Keyframe();
                        keyOn.value = 1;
                        keyOn.time = time;

                        curve.AddKey(keyBefore);
                        curve.AddKey(keyOn);
                        curve.AddKey(keyAfter);

                        AnimationUtility.SetEditorCurve(anim, goBinding, curve);
                    }
                }
            }
            AssetDatabase.SaveAssets();
            AssetDatabase.Refresh();
        }
    }