Position of object

Questions
1

Hello
I asked this question previously on this forum:

I’m trying to find the position of objects inside my blender model. It’s a similar object and issue as the previous example, except with a glTF loader due to loading time. With this model, I can simply get the meshes position using mesh.position. However I have some objects that are groups of meshs like so:

image
image1173×685 115 KB

However, now when I use the following code:

  mesh.geometry.computeBoundingBox();
  var center = new THREE.Vector3();
  mesh.geometry.boundingBox.getCenter(center);
  mesh.geometry.center();
  mesh.position.copy(center);

The position is set the centre. I can’t seem to find how I can return the position of the meshes inside the group… The information doesn’t appear to be in the geometry attribute or the position attibute. Any ideas on how I could return the position of the object?

Thanks in advance

2

The center of the bounding box of the geometry is in the object’s local coordinate system. You can convert it to a world position by using the object’s localToWorld method.

Object3D.position is a position in the parent object’s local coordinate system. You can convert it to a world position by using the parent object’s localToWorld method.

Make sure to apply localToWorld to a copy of the vector, because it outputs to the argument.

3

Hey, thanks.
Do you mean converting the mesh to a local to world? It doesn’t seem to have an affect. I have the following code:

  var light = this.getObject("l01"); // Retrieves Object3D in the scene
  light = light.children[0]; // To get the first mesh in the group

  light.geometry.computeBoundingBox(); 
  var center = new THREE.Vector3();
  light.geometry.boundingBox.getCenter(center);
  light.geometry.center();
  light.position.copy(center);
  var vec = new THREE.Vector3();

  light.localToWorld(vec);
        moonGlow.position.set(
    vec.x,
    vec.y,
    vec.z
  );

I have tried it without the bounding box code too.
Let me know,
Cheers

4

localToWorld converts the argument from local to world. In your code above, the argument is (0,0,0).

Try with:

var vec = new THREE.Vector3().copy(light.position);
5

Do I still compute the bounding box? And do I call localToWorld at the end?
I’m really struggling to work this out.

6

Sorry to have misled you.

var light = this.getObject("l01"); // Retrieves Object3D in the scene
light = light.children[0]; // To get the first mesh in the group
if ( ! light.geometry.boundingBox ) {
    light.geometry.computeBoundingBox();
}

//Assuming moonGlow is positioned globally, i.e. `scene.add( moonGlow )`:
light.localToWorld( light.geometry.boundingBox.getCenter( moonGlow.position ) );