Convert root bone position to Unity world position

HansAdler

Hi, I need to convert the bone position (X,Y) from the Spine coordinates to the Unity position.

I'm using the SkeletonGraphic to add the Spine animation as a child of a Unity UI Canvas. I would like to be able to convert the start and end positions of the root bone (within the animation) to the Unity transform position (unity world position or local position within the parent of the SkeletonGraphic) so that I can move the transform of the SkeletonGraphic to account for root motion when the animation is complete.

I haven't found a way to do this conversion. Does anyone know how to do that?

Thank you,
Hans

Pharan

Because it's the root bone, the root bone position is always the local position within the parent of the SkeletonGraphic.

If you want world, you can take that local position and pass it to TransformPoint.

var worldPosition = parentTransform.TransformPoint(localPosition);

HansAdler

I tried that, but it didn't work the way I expected. In the Complete callback, the root bone has moved several hundred pixels, but the offset of the root bone (bone.X, bone.Y) is (2.5,0). There is a large scale factor that doesn't get fixed by using TransformPoint. Where does the scale factor come from?

Pharan

I think there's a scale factor on the Canvas you need to account for, depending on your Canvas settings.

Additionally, by default, SkeletonData assets import the json at 0.01 scale to match Unity's 100 pixel to unity unit scale, so also note that. (ie, with that scale, 100 units in Spine will be 1 unit in Unity). I think you already knew that, but I wanted to mention it just for completeness.

HansAdler

Ok, that helps. Thanks.
Where is the 100:1 scale setting set in Spine?
Thank you.

Pharan

In Spine itself, there is no setting. The scaling is done at runtime, per runtime and Spine doesn't store a scale setting in the json or the project.

In Spine-Unity, the json scale setting is saved per-skeleton in its SkeletonData Asset (this is the generated asset you get when you import your skeleton's json).