constructor( editor, object = null, newMaterial = null, materialSlot = - 1 ) {

		super( editor );

		this.type = 'SetMaterialCommand';
		this.name = editor.strings.getKey( 'command/SetMaterial' );

		this.object = object;
		this.materialSlot = materialSlot;

		this.oldMaterial = ( object !== null ) ? editor.getObjectMaterial( object, materialSlot ) : null;
		this.newMaterial = newMaterial;

	}
@param {Editor} editor
@param {THREE.Object3D|null} object
@param {THREE.Material|null} newMaterial
@param {number} [materialSlot=-1]
@constructor