Position relative to bone joint (bone local space)

[santarcade]

Hi guys,

after beating my head against this for a while, I came to the conclusion that I need a break and possibly some support.
I want to calculate the position of theObject mesh in the local space of theBone which is attached to theMesh.

The code I write for it is:
 

// combine the bone World Matrix with the transform of the mesh
var boneInverse = theBone.getWorldMatrix().multiply(theMesh.getWorldMatrix());
boneInverse.invert();

// calculate object position relative to the bone joint
console.log('object world position: '+objectMesh.position);
var relPos = BABYLON.Vector3.TransformCoordinates(objectMesh.position, boneInverse);
console.log('object rel position: '+relPos);

But the problem is I keep getting weird results...
I tried switching theBone.getWorldMatrix() with theBone.getAbsoluteMatrix() with no luck.
It is still unclear the difference between the two me and I could not find anything in the doc.

Halp!

[GameMonetize]

Hey

this class could be helpful: https://github.com/BabylonJS/Babylon.js/blob/master/src/Debug/babylon.skeletonViewer.ts

(mainly this function: https://github.com/BabylonJS/Babylon.js/blob/master/src/Debug/babylon.skeletonViewer.ts#L40)

[santarcade]

Deltakosh!
Thank you very much for the reply: this is exactly what I ended up coding, a skeleton visualizer and a bone matrix updater.
Turned out, my calculations were correct the problem I experienced instead was related to how I override bone matrixes while an animation is playing: basically when calculating how to dynamically adjust the rotation of a bone, I was using theBone.getWorldMatrix() but the resulting matrix was not up-to-date.
So my bone adjustment looked wrong, while it was just the matrix that was out-dated: so a small function such as this one https://github.com/BabylonJS/Babylon.js/blob/master/src/Debug/babylon.skeletonViewer.ts#L119 solved!

Now I'm experiencing a new issue though: I have an additional mesh attached to a bone of the skeleton for which I override the matrix of the animation: while the main mesh animates using my adjusted values, the attached mesh plays the original animation, without my overrides. I'm running 2.3.0: any clue?

I will try to update to 2.4.0 preview, just to see if it changes.
Thanks so far!
 

[GameMonetize]

hard to tell but if you can provide a PG it's gonna help me a lot

[santarcade]

Ok, I will try to extract an example as soon as I can.
Thanks so far!