Access instancedMesh's sub-instance origin and tranform with pivot

Questions
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1

Hi guys.I’m working on a scene that may needs large amount of animating models.So I have to use instancedMesh.But i’ve encountered some transforming issues.Below is a instancing ferrari demo, i tried to make the wheel rotating normally( around it’s center) but failed.since the sub-meshes are already instanced, the origin of itself is unaccessable.So the typical “pivot” way cannot work.Is there any chance to solve this？Thanks. :rofl:
Instancing Ferrari Demo

2

Just figured that out.The instancedMesh’s sub-instance is already “pivoted”, so the solution is to “unPivot”.Based on some soucecode in InstancedMesh: Add bounding volumes. by Mugen87 · Pull Request #21507 · mrdoob/three.js · GitHub
that it is possible to get the sub-instance’s volume center as offset.And the “unpivot” way is adding a parent pivot to the dummy object,and:

  1. sub the dummy’s position with offset
  2. add the parentDummy’s position with offset
  3. update parentDummy’s rotation in the loop
  4. updating instanceMatrix with dummy’s matrixWorld
    here is a working example:

Instancing Ferrari Demo Justified
It would be nice if anyone has other better solution…