Size object Box3, after applyMatrix4

Questions
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1

After apply Matrix4 the object get extrange size result.

let obj = TC.transformControls.object;
let m = new THREE.Matrix4();
m.set(trans.rot.get(0) * trans.sle, trans.rot.get(1) * trans.sle, trans.rot.get(2) * trans.sle, trans.tra.get(0),
trans.rot.get(3) * trans.sle, trans.rot.get(4) * trans.sle, trans.rot.get(5) * trans.sle, trans.tra.get(1),
trans.rot.get(6) * trans.sle, trans.rot.get(7) * trans.sle, trans.rot.get(8) * trans.sle, trans.tra.get(2),
0, 0, 0, 1);
obj.applyMatrix4(m);

let vec3 = new THREE.Vector3();
let box3 = new THREE.Box3().setFromObject(obj);
box3.getSize(vec3);
let radius = box3.getBoundingSphere(new THREE.Sphere()).radius;

The “radius” variable give a unexpected size…

It seems somthing easy but i cant find the way to resolve it correclty. Thank you so much.

2

It would be nice to share online debuggable example (CodePen, CodeSandBox, JSFiddle). Otherwise it is hard to foresee the meaning of “unexpected size” Nevertheless, here are a few comments:

  • bounding boxes are axes aligned, as a result, the bounding box might appear larger than expected
  • setFromObject may give a larger than expected result if it is used without a second parameter precise=true
  • getBoundingSphere is run on the bounding box, not on the object, so the result might be even bigger, than expected.