Setting matrixWorld and attaching to parent overwrites the rotations with [I]

Questions
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1

I’m trying to load the helmet GLTF and replace each Mesh with its “thick” Wireframe equivalent but I end up with an unexpected 90 degree pitch in the end.

2022-11-10 13_48_42-Edit fiddle - JSFiddle - Code Playground - Brave

I traverse the node tree twice. On the first pass I run updateWorldMatrix() on each node, then create a new Wireframe node for each Mesh node I find and copy the Mesh.matrixWorld into the new Wireframe.matrixWorld. I don’t make any changes to the node tree on the first pass; the new Wireframe nodes and other bookkeeping data go into a temporary map structure.

On the second traversal pass, I assign each of the new Wireframe nodes to their proper parents in the node tree using parent.attach().

Finally, I iterate through the temporary map to delete the original Mesh nodes from the node tree.

The parent.attach() call seems to be squashing the rotations and I don’t know what I’m missing. What is the proper procedure to give a node a world rotation and then attach it to another node so that it calculates a valid local reference frame?

Before you go, let me play you something on my fiddle: Wireframe#3 - JSFiddle - Code Playground

2

If you want to add an object of lines to the object it was made from (a base object), then why do you apply .worldMatrix of the base object to it?

3

I want to attach the object of lines to the parent of the base object, not to the base object itself. I’m trying to replace the original base object with a wireframe version of itself.

4

Seems I succeeded with it here :thinking: LDraw-like edges - #42 by prisoner849

1 Like
5

Thank you. I’ll check it out.

6

Fixed by attaching the new node first and then copying the position and quaternion.

parent.attach(child)
child.position.copy(sibling.position)
child.quaternion.copy(sibling.quaternion)

Treat Object3D.matrixWorld as a read-only value.

7

have u checked the axis? make sure u are using y axis instead of the z axis