text: /**
   * @author mrdoob / http://mrdoob.com/
   */
  /**************************************************************
   *	GeometryUtils geometry对象的工具集
   **************************************************************/
  THREE.GeometryUtils = {
  
  	/*
  	///merge方法将两个几何体对象或者Object3D里面的几何体对象合并,(使用对象的变换)将几何体的顶点,面,UV分别合并.
  	///NOTE: merge方法在新版本中已经放到了Geomet对象下面,这里保留为了向后兼容.
  	*/
  	///<summary>merge</summary>
  	///<param name ="geometry1" type="Geometry">几何体对象.</param>
  	///<param name ="geometry2" type="Geometry">要被合并的几何体.</param>
  	///<param name ="matrix" type="Matrix4">可选参数,变换矩阵,当指定了该参数,合并后的对象会应用变换</param>
  	///<param name ="materialIndexOffset" type="Number">材质索引偏移量</param>
  	///<returns type="Number">返回合并后的几何体对象</returns>	
  	merge: function ( geometry1, geometry2, materialIndexOffset ) {
  
  		console.warn( 'THREE.GeometryUtils: .merge() has been moved to Geometry. Use geometry.merge( geometry2, matrix, materialIndexOffset ) instead.' );
  
  		var matrix;
  
  		if ( geometry2 instanceof THREE.Mesh ) {
  
  			geometry2.matrixAutoUpdate && geometry2.updateMatrix();
  
  			matrix = geometry2.matrix;
  			geometry2 = geometry2.geometry;
  
  		}
  
  		geometry1.merge( geometry2, matrix, materialIndexOffset );	//调用Geometry.merge方法,将geometry2对象的方法合并到geometry1对象中.
  
  	},
  
  	/*
  	///center方法通过计算出当前Geometry对象的立方体界限的中心,获得当前对象的中心.
  	*/
  	///<summary>center</summary>
  	///<param name ="geometry" type="Geometry">几何体对象.</param>
  	///<returns type="Vector3">返回中心点坐标</returns>
  	center: function ( geometry ) {
  
  		console.warn( 'THREE.GeometryUtils: .center() has been moved to Geometry. Use geometry.center() instead.' );
  		return geometry.center();	//返回中心点坐标
  
  	}
  
  };
  