第一段是原本画网格的代码 第二段我使用geometry.merge()方法的代码 不知道哪里写错了 不报错 也出不来 请前辈指教

function initObject() {
                //1.在x轴上定义两个点p1 p2
                var geometry = new THREE.Geometry();
                geometry.vertices.push(new THREE.Vector3(-500, 0, 0));
                geometry.vertices.push(new THREE.Vector3(500, 0, 0));
                //2.主要在于这里的算法，从右、下角开始画
                for (var i = 0; i <= 20; i++) {
                    //画横线
                    var line = new THREE.Line(geometry, new THREE.LineBasicMaterial({ color: 0x000000, opacity: 0.2 }));
                    line.position.z = (i * 50) - 500;
                    scene.add(line);


                    var line = new THREE.Line(geometry, new THREE.LineBasicMaterial({ color: 0x000000, opacity: 0.2 }));
                    line.position.x = (i * 50) - 500;
                    line.rotation.y = 90 * Math.PI / 180;   //转90度
                    scene.add(line);

                }
            }

function initObject() {  
                var geometry = new THREE.Geometry();  
                var allLine=new THREE.Geometry();
                geometry.vertices.push( new THREE.Vector3( - 500, 0, 0 ) );  
                geometry.vertices.push( new THREE.Vector3( 500, 0, 0 ) ); 
                for ( var i = 0; i <= 20; i ++ ) { 
                    var line = new THREE.Line( geometry, new THREE.LineBasicMaterial( { color: 0x000000, opacity: 0.2 } ) );
                    line.position.z = ( i * 50 ) - 500;  
                    allLine.merge(line.geometry,line.matrix) 
                    var line = new THREE.Line( geometry, new THREE.LineBasicMaterial( { color: 0x000000, opacity: 0.2 } ) );
                    line.position.x = ( i * 50 ) - 500;  
                    line.rotation.y = 90 * Math.PI / 180;  
                    allLine.merge(line.geometry,line.matrix)
                }  
                allLineMesh=new THREE.Mesh(allLine,new THREE.MeshBasicMaterial({color:0x000000,side:THREE.DoubleSide}))
                scene.add( allLineMesh );  
            }