Centering and Resizing GLTF models automatically in Three.js

Question

After downloading 3D models from sketchfab.com and importing them into a Three.js scene, they are most of the times not centered and their size is very big.

Is there a way to automatically center and scale gltf models using a script or a software (working on Linux) or otherwise to do it on-the-fly in Three.js and having the camera to move around the object using OrbitControls.

Answer 1

Yep. This code takes a node and finds its size and centerpoint, then rescales it so the max extent is 1 and its centered at 0,0,0, and above the ground on the y axis.

    var mroot = yourScene;
    var bbox = new THREE.Box3().setFromObject(mroot);
    var cent = bbox.getCenter(new THREE.Vector3());
    var size = bbox.getSize(new THREE.Vector3());

    //Rescale the object to normalized space
    var maxAxis = Math.max(size.x, size.y, size.z);
    mroot.scale.multiplyScalar(1.0 / maxAxis);
    bbox.setFromObject(mroot);
    bbox.getCenter(cent);
    bbox.getSize(size);
    //Reposition to 0,halfY,0
    mroot.position.copy(cent).multiplyScalar(-1);
    mroot.position.y-= (size.y * 0.5);

Answer 2

I resized in REACT like this!

import React, { useState, useRef, useEffect } from "react";
import { GLTFLoader } from "three/examples/jsm/loaders/GLTFLoader";
const Earth = () => {
const [model, setModel] = useState();
useEffect(() => {
    new GLTFLoader().load("scene.gltf", (model) => {
      model.scene.scale.set(0.03, 0.03, 0.03);
      setModel(model);
    });
  });
  return model ? <primitive object={model.scene} /> : null;
};

Just call <Earth />