GLB bone rotation

[peterimg]

Hi

I have GLB model loaded with skeletal mesh. Now the skeleton bone I cant rotate or move. I need to pick up its parent and rotate them.

Now when I pick up bone in inspector with a gizmo I can rotate 90 degrees in one direction. and X y z in rotation is changed in only 1 direction.

Now when i use rotate() method i can only add amount of angles to rotate by. So its good for animation in onBeginAnimation.
Now the question:

How can I rotate a bone from 0 to 90deg in its local axis and animate just 1 value from 0 to 90 (Math.PI / 2) and set it to a value somehow?

So I can always set it to 0 and it will coma back.

I have terrible results with rotationQuaterion. I cant make it work with code.

But gizmo in inspector works no problems and there are input fields to set to 0 and it goes to 0 to 90 its moved to 90. Cant work this out at all.

[peterimg]

I just want to be able to set bone rotation in Angle value like 0 90 75 and back from them. Not with adding missing part but with a value

[regna]

Have you tried using Bone.setRotationQuaternion():

bone.setRotationQuaternion(rotation, BABYLON.Space.LOCAL);

// or

bone.setRotationQuaternion(rotation, BABYLON.Space.WORLD);

[peterimg]

Hi @regna

But when you load GLB files your bones do nothing. You need to get their parent TransformNode and then this method is not available.

TypeError: boneTransfNode.setRotationQuaternion is not a function

What to do with it in GLB loaded models that’s the question?

[regna]

Ah, I’m not too familiar with glTF bones. It looks like you’re right that you have to use the Transform Node according to the glTF Skinning Documentation.

Can you show an image/video of how setting the Transform Node’s rotation gives an unexpected result (preferably while the skeleton is in a T-pose)?

[peterimg]

@regna

Not realy cant show models but any model will do.

Just the rotate method works that adds increments of rotation. There is no method that sets A value that relates to local position.

I do not know why it works in .babylon file model but not glTF

Can you find some other way to rotate transformNode?

[regna]

@peterimg

I do not know why it works in .babylon file model but not GLB

I work with .babylon instead of glTF, so maybe that’s why I haven’t seen this issue. There may be a special way to rotate glTF bones that our glTF expert @bghgary could help us with

[peterimg]

Hi @bghgary

Do you have any suggestions on this topic? I actually saw some of your tickets that you help with but I could not find a solution. Also, all the Docs have examples with .babylon file as well.

Would be nice to have a solution to this issue.

Regards
Peter

[bghgary]

This is difficult to help without a playground or something so I can look at what you are doing. Can you provide some code / assets (ideally a playground) to look at so I can more easily help?

[peterimg]

Hi @bghgary

Sorry for late replay just found a bug in Babylon that I was investigating for you for some time Opened ticket today

So here is a PG:

Babylon.js Playground

And the problem is I need to get Bone Transform node to rotate the bone.

But I can only use rotate function that takes increments of rotation.

i would like to use GSAP with the animations and I need to have a angle value and animate it like that:

Animation 1:
Form 0 to 30 deg.

Animation 2:
From 30 to 60.

Cancel Animation:
Rotation back to 0 so it will animate from any angle to 0.

and it needs to be back to 0 so initial position.

When I use increments I cant use GSAP that takes a value from X to Y and animates value in between.

Method setRotate looks promising but it does not exist on TransformNode.

So how I can ratate that bone in its local coordinates system like the gizmo does?

When I grab the gizmo of that bone and only pull by red circle its doing what I want but then It uses Quaterion that is animating 4 values and that mess up the animation. Already tried that.

[bghgary]

I think you are asking how to manipulate a node transform and it has nothing to do with bones.

Here is what I think you trying to do: https://playground.babylonjs.com/#BUJL56#3

Basically, the Arm has an existing rest rotation and set absolute angles relative to the rest rotation. That’s what I did in the playground. Is this what you’re looking for?

[peterimg]

HI.

I made the initial test but it works. Thanks for the solution If I will have more questions about it I will coma back to you on this thread.

Regards
Peter