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();

function DirectionalLightHelper( light, size, color ) {

	Object3D.call( this );

	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();

}

DirectionalLightHelper.prototype = Object.create( Object3D.prototype );
DirectionalLightHelper.prototype.constructor = DirectionalLightHelper;

DirectionalLightHelper.prototype.dispose = function () {

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

};

DirectionalLightHelper.prototype.update = function () {

	_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 };