Editor: Move to ES6 modules (2nd attempt).

[Mugen87]

This PR moves the editor to ES6 modules. I've found now a way in order to not rely on build/three.js anymore which was a blocker for the previous PR (see #16968).

@mrdoob Please review how app.js was changed. The problem is that the file is used in the editor (as part of the player) and in published projects. Hence it's not possible to import three.modules.js within the file since the path depends on the use case. THREE is now injected via new APP.Player( THREE );. It's also necessary to define THREE into the global namespace so the editor scripts are able to run.

We might want to merge the PR at the beginning of the next dev cycle since this needs some careful testing^^.

[mrdoob]

Thanks for diving into this! 🙏

[mrdoob]

Hmm... Similarly to when we changed the examples to use modules I think it'll make things easier to use the THREE namespace for now:

import * as THREE from '../../build/three.module.js';

Instead of:

import {
	AnimationMixer,
	CameraHelper,
	Color,
	DirectionalLightHelper,
	HemisphereLightHelper,
	Mesh,
	MeshBasicMaterial,
	ObjectLoader,
	PerspectiveCamera,
	PointLightHelper,
	Scene,
	SkeletonHelper,
	SphereBufferGeometry,
	SpotLightHelper,
	Vector3
} from '../../build/three.module.js';

[Mugen87]

Similarly to when we changed the examples to use modules I think it'll make things easier to use the THREE namespace for now:

Okay, done 👍

[mrdoob]

Lets do this! 😁
I'll test it over the weekend and fix whatever I find.

[mrdoob]

Thanks!