如何将全局转换应用于子对象

Question

I'm trying to apply a global position (from a WebVR controller) to the child object of a parent that has several transformations. It's not a first generation child, though there aren't any transformations applied to any of the object in between:

Scene
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Object (with transformations)
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Object (no transformations)
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Child ( cube ) (Where I want to apply a global position)

If I apply these transformations to a cube that's a direct child of the scene, it works fine:

cube.position.copy(globalPosition);

But I need to apply it to the child object. I've tried to convert the global position to the local one by doing:

const worldToLocal = new THREE.Matrix4().getInverse(cube.parent.matrixWorld);
cube.position.copy(globalPosition);
cube.applyMatrix(worldToLocal);

But the cube is not in the same position as if it were a child of the scene. Not sure what else to try, thanks for the help!

Answer 1

Good day everyone! I advice to regroup your meshes. If you want to change position in world of all group, you need to apply position on parent object, transform use on child objects. For grouping try to use empty mesh and use method parentMesh.add(childMesh). Hope this help's ;)

Answer 2

I got stuck with this issue a long time ago, and ended up grouping it differently and making cube a direct child of the scene and that seemed to work at the time, but now, cube 's previous parents started acting weird, they would rotate to a strange position and not move if I tried to change their position or rotation. That's why I know wanted to fix it properly.

So I ended up doing something similar to what @WestLangley mentioned, but I also need to transform the rotation, so I used matrices:

const worldToLocal = new THREE.Matrix4().getInverse(cube.parent.matrixWorld);
const poseMatrix = new THREE.Matrix4();
poseMatrix.makeRotationFromQuaternion(globalQuaternion);
poseMatrix.setPosition(globalPosition);
poseMatrix.multiplyMatrices(worldToLocal, poseMatrix);
poseMatrix.decompose(cube.position, cube.quaternion, {});

Thanks a lot for everyone's help!