Add visual Octree Helper (#23478)

[carlssonk]

Simple visual Octree helper for showing a visual representation of the Octree data structure. Reference (#23478)

Usage:

import { Octree } from 'three/examples/jsm/math/Octree.js';
import { OctreeHelper } from 'three/examples/jsm/helpers/OctreeHelper.js'

const octree = new Octree();
octree.fromGraphNode("Your Group or Object3D model here");

const octreeHelper = new OctreeHelper(octree)
scene.add( octreeHelper )

Note: OctreeHelper should be instantiated after we call octree.fromGraphNode.

Let me know if anything can be imporved.

[mrdoob]

Thanks!

[mrdoob]

I've added it to games_fps:

three.js/examples/games_fps.html

Lines 438 to 448 in dd7bd0f

	const helper = new OctreeHelper( worldOctree );
	helper.visible = false;
	scene.add( helper );
	const gui = new GUI( { width: 200 } );
	gui.add( { debug: false }, 'debug' )
	.onChange( function ( value ) {
	helper.visible = value;
	} );