<!-- NEW3 — TEST 3 · THE RIVER'S JOURNEY · part 293 -->

	 */
	dispose() {

		super.dispose();

		this.children[ 0 ].geometry.dispose();
		this.children[ 0 ].material.dispose();

	}

	/**
	 * Updates the helper to match the position and direction of the
	 * light being visualized.
	 */
	update() {

		const mesh = this.children[ 0 ];

		if ( this.color !== undefined ) {

			this.material.color.set( this.color );

		} else {

			const colors = mesh.geometry.getAttribute( 'color' );

			_color1.copy( this.light.color );
			_color2.copy( this.light.groundColor );

			for ( let i = 0, l = colors.count; i < l; i ++ ) {

				const color = ( i < ( l / 2 ) ) ? _color1 : _color2;

				colors.setXYZ( i, color.r, color.g, color.b );

			}

			colors.needsUpdate = true;

		}

		this.matrixWorldNeedsUpdate = true;

		this.light.updateWorldMatrix( true, false );

		mesh.lookAt( _vector$1.setFromMatrixPosition( this.light.matrixWorld ).negate() );

	}

}

/**
 * The helper is an object to define grids. Grids are two-dimensional
 * arrays of lines.
 *
 * ```js
 * const size = 10;
 * const divisions = 10;
 *
 * const gridHelper = new THREE.GridHelper( size, divisions );
 * scene.add( gridHelper );
 * ```
 *
 * @augments LineSegments
 */
class GridHelper extends LineSegments {

	/**
	 * Constructs a new grid helper.
	 *
	 * @param {number} [size=10] - The size of the grid.
	 * @param {number} [divisions=10] - The number of divisions across the grid.
	 * @param {number|Color|string} [color1=0x444444] - The color of the center line.
	 * @param {number|Color|string} [color2=0x888888] - The color of the lines of the grid.
	 */
	constructor( size = 10, divisions = 10, color1 = 0x444444, color2 = 0x888888 ) {

		color1 = new Color( color1 );
		color2 = new Color( color2 );

		const center = divisions / 2;
		const step = size / divisions;
		const halfSize = size / 2;

		const vertices = [], colors = [];

		for ( let i = 0, j = 0, k = - halfSize; i <= divisions; i ++, k += step ) {

			vertices.push( - halfSize, 0, k, halfSize, 0, k );
			vertices.push( k, 0, - halfSize, k, 0, halfSize );

			const color = i === center ? color1 : color2;

			color.toArray( colors, j ); j += 3;
			color.toArray( colors, j ); j += 3;
			color.toArray( colors, j ); j += 3;
			color.toArray( colors, j ); j += 3;

		}

		const geometry = new BufferGeometry();
		geometry.setAttribute( 'position', new Float32BufferAttribute( vertices, 3 ) );
		geometry.setAttribute( 'color', new Float32BufferAttribute( colors, 3 ) );

		const material = new LineBasicMaterial( { vertexColors: true, toneMapped: false } );

		super( geometry, material );

		this.type = 'GridHelper';

	}

	/**
	 * Frees the GPU-related resources allocated by this instance. Call this
	 * method whenever this instance is no longer used in your app.
	 */
	dispose() {

		super.dispose();

		this.geometry.dispose();
		this.material.dispose();

	}

}

/**
 * This helper is an object to define polar grids. Grids are
 * two-dimensional arrays of lines.
 *
 * ```js
 * const radius = 10;
 * const sectors = 16;
 * const rings = 8;
 * const divisions = 64;
 *
 * const helper = new THREE.PolarGridHelper( radius, sectors, rings, divisions );
 * scene.add( helper );
 * ```
 *
 * @augments LineSegments
 */
class PolarGridHelper extends LineSegments {

	/**
	 * Constructs a new polar grid helper.
	 *
	 * @param {number} [radius=10] - The radius of the polar grid. This can be any positive number.
	 * @param {number} [sectors=16] - The number of sectors the grid will be divided into. This can be any positive integer.
	 * @param {number} [rings=16] - The number of rings. This can be any positive integer.
	 * @param {number} [divisions=64] - The number of line segments used for each circle. This can be any positive integer.
	 * @param {number|Color|string} [color1=0x444444] - The first color used for grid elements.
	 * @param {number|Color|string} [color2=0x888888] -  The second color used for grid elements.
	 */
	constructor( radius = 10, sectors = 16, rings = 8, divisions = 64, color1 = 0x444444, color2 = 0x888888 ) {

		color1 = new Color( color1 );
		color2 = new Color( color2 );

		const vertices = [];
		const colors = [];

		// create the sectors

		if ( sectors > 1 ) {

			for ( let i = 0; i < sectors; i ++ ) {

				const v = ( i / sectors ) * ( Math.PI * 2 );

				const x = Math.sin( v ) * radius;
				const z = Math.cos( v ) * radius;

				vertices.push( 0, 0, 0 );
				vertices.push( x, 0, z );

				const color = ( i & 1 ) ? color1 : color2;

				colors.push( color.r, color.g, color.b );
				colors.push( color.r, color.g, color.b );

			}

		}

		// create the rings

		for ( let i = 0; i < rings; i ++ ) {

			const color = ( i & 1 ) ? color1 : color2;

			const r = radius - ( radius / rings * i );

			for ( let j = 0; j < divisions; j ++ ) {

				// first vertex

				let v = ( j / divisions ) * ( Math.PI * 2 );

				let x = Math.sin( v ) * r;
				let z = Math.cos( v ) * r;

				vertices.push( x, 0, z );