three.js/src/helpers/DirectionalLightHelper.js

import { Vector3 } from '../math/Vector3.js';
import { Object3D } from '../core/Object3D.js';
import { Line } from '../objects/Line.js';
import { Float32BufferAttribute } from '../core/BufferAttribute.js';
import { BufferGeometry } from '../core/BufferGeometry.js';
import { LineBasicMaterial } from '../materials/LineBasicMaterial.js';

const _v1 = new Vector3();
const _v2 = new Vector3();
const _v3 = new Vector3();

class DirectionalLightHelper extends Object3D {

	constructor( light, size, color ) {

		super();
		this.light = light;
		this.light.updateMatrixWorld();

		this.matrix = light.matrixWorld;
		this.matrixAutoUpdate = false;

		this.color = color;

		if ( size === undefined ) size = 1;

		let geometry = new BufferGeometry();
		geometry.setAttribute( 'position', new Float32BufferAttribute( [
			- size, size, 0,
			size, size, 0,
			size, - size, 0,
			- size, - size, 0,
			- size, size, 0
		], 3 ) );

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

		this.lightPlane = new Line( geometry, material );
		this.add( this.lightPlane );

		geometry = new BufferGeometry();
		geometry.setAttribute( 'position', new Float32BufferAttribute( [ 0, 0, 0, 0, 0, 1 ], 3 ) );

		this.targetLine = new Line( geometry, material );
		this.add( this.targetLine );

		this.update();

	}

	dispose() {

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

	}

	update() {

		_v1.setFromMatrixPosition( this.light.matrixWorld );
		_v2.setFromMatrixPosition( this.light.target.matrixWorld );
		_v3.subVectors( _v2, _v1 );

		this.lightPlane.lookAt( _v2 );

		if ( this.color !== undefined ) {

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

		} else {

			this.lightPlane.material.color.copy( this.light.color );
			this.targetLine.material.color.copy( this.light.color );

		}

		this.targetLine.lookAt( _v2 );
		this.targetLine.scale.z = _v3.length();

	}

}


export { DirectionalLightHelper };