Making human taller - skeleton - Godot Community Forums

Making human taller - skeleton

JRRRRRR

Hi. In my code I make a human taller by moving verts. The only problem is changing the skeleton - I thought setting bone_rest would be the same as moving a bone in edit mode in blender as opposed to moving a bone in pose mode in blender, but I was wrong and setting bone_rest makes the verts follow the bones. I can't see any methods in the docs that relate to this. How would I go about editing the underlying skeleton?

cybereality

Bones only really affect the rotation, not the position.

JRRRRRR

I want to play a sort of casual idle animation while the user is editing the character, without changing the skeleton it goes a bit pear shaped.

This is with the upper arm elongated before/after https://i.imgur.com/MPVwjP0.png

I am assuming it's rotating around the position of the bone it's attached to which is wrong after the arm length change.

JRRRRRR

I found what to do. For anyone who comes across this topic while searching (I frequently end up on my own help posts when googling lol) the solution:

After editing the bone_rest transformation, I had to edit the 'skin' property of the mesh. The skin has a bunch of transforms which the Khronos gltf spec describes thusly:

an OPTIONAL inverseBindMatrices property that points to an accessor with inverse bind matrices data used to bring coordinates being skinned into the same space as each joint.
(https://github.com/KhronosGroup/glTF/blob/main/specification/2.0/Specification.adoc#skins)

You can remove the skin and launch a scene, the animation will play fine but if you edit the rest pose like I did you still have problems. I updated these new values with the following:

var numBones = skel.get_bone_count()
	for n in range(numBones):
		var gp = skel.get_bone_global_pose(n)
		var gpi = gp.inverse()
		skin.set_bind_pose(n,gpi)

Importantly, I set the animation of the skeleton to a 'default pose' I had created, which is literally just 1 keyframe of the skeleton in it's own starting position (I also let 1 frame pass so it was updated, I don't know if this is actually necessary - I was doing it for another part of my scene that needed it so I thought I'd mention it). The bone_global_pose will be different if it's in any part of an animation (I'm sure you can get it another way but at this point I have no hair left to pull out).