updateMatrixWorld( force ) {

		this.position.set( 0, 0, 0 );

		this.scale.set( 0.5 * this.size, 0.5 * this.size, 1 );

		this.lookAt( this.plane.normal );

		this.translateZ( - this.plane.constant );

		super.updateMatrixWorld( force );

	}
The side length of plane helper.

@type {number}
@default 1