rotateY( angle ) {

		// rotate geometry around world y-axis

		_m1.makeRotationY( angle );

		this.applyMatrix4( _m1 );

		return this;

	}
Rotates the geometry about the Y axis. This is typically done as a one time
operation, and not during a loop. Use {@link Object3D#rotation} for typical
real-time mesh rotation.

@param {number} angle - The angle in radians.
@return {BufferGeometry} A reference to this instance.