three.js/src/lights/DirectionalLight.js

/**
 * @author mrdoob / http://mrdoob.com/
 * @author alteredq / http://alteredqualia.com/
 */

THREE.DirectionalLight = function ( color, intensity ) {

	THREE.Light.call( this, color );

	this.type = 'DirectionalLight';

	this.position.set( 0, 1, 0 );
	this.updateMatrix();

	this.target = new THREE.Object3D();

	this.intensity = ( intensity !== undefined ) ? intensity : 1;

	this.shadow = new THREE.LightShadow( new THREE.OrthographicCamera( - 500, 500, 500, - 500, 50, 5000 ) );

};

THREE.DirectionalLight.prototype = Object.create( THREE.Light.prototype );
THREE.DirectionalLight.prototype.constructor = THREE.DirectionalLight;

THREE.DirectionalLight.prototype.copy = function ( source ) {

	THREE.Light.prototype.copy.call( this, source );

	this.intensity = source.intensity;
	this.target = source.target.clone();

	this.shadow = source.shadow.clone();

	return this;

};