API Design: Object3D.position is read-only

Description of the problem

The position property of Object3D, and more importantly all it’s ancestors, is read-only. The default behavior of Object.defineProperties sets properties that way — that’s what’s used in Object3D.js.

Consider the scenario where a user wants to subclass Mesh.js.

var Particle = function (positionVector, mass, radius) {

    THREE.Mesh.call(this);

    // will cause read-only assignment error
    this.position = positionVector; 
   ...
    this.geometry = new THREE.SphereGeometry(this.radius, 10, 10);
    this.material = this.getMaterial({
        color: 0xff0000
    });
}

Particle.prototype = Object.create(THREE.Mesh.prototype);
Particle.prototype.constructor = Particle;

Copying or clone methods of Vector3 are problematic because there’s no way to preserve the original reference passed (or ‘injected’ if you want to be tedious) in the constructor above. This prevents elegant subclassing for child classes of Object3D like Mesh, and I think is a mistake in an otherwise very-well designed library. Please consider altering the relevant Object.defineProperties line to add writable: true.

Three.js version

• Dev
• r76
• …

Browser

• All of them
• Chrome
• Firefox
• Internet Explorer

OS

• All of them
• Windows
• Linux
• Android
• IOS

Hardware Requirements (graphics card, VR Device, …)

N/A