three.js/src/scenes/FogExp2.js

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

THREE.FogExp2 = function ( color, density ) {

	this.name = '';

	this.color = new THREE.Color( color );
	this.density = ( density !== undefined ) ? density : 0.00025;

};

THREE.FogExp2.prototype.clone = function () {

	return new THREE.FogExp2( this.color.getHex(), this.density );

};