 canvas default
	const near = 0.1;
	const far = 100;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.set( 0, 10, 20 );

	class MinMaxGUIHelper {

		constructor( obj, minProp, maxProp, minDif ) {

			this.obj = obj;
			this.minProp = minProp;
			this.maxProp = maxProp;
			this.minDif = minDif;

		}
		get min() {

			return this.obj[ this.minProp ];

		}
		set min( v ) {

			this.obj[ this.minProp ] = v;
			this.obj[ this.maxProp ] = Math.max( this.obj[ this.maxProp ], 