具有对角线的ExtrudeGeometry

Question

我创建了一个ExtrudeGeometry对象，使用了three.js lib，代码如下：

   var extrudeSettings = {};
   extrudeSettings.bevelEnabled = false;
   extrudeSettings.bevelSegments = 0;
   extrudeSettings.steps =2;
   //create a shape
   var rectShape;
   ......
   //add the shape to scene
   var geometry = new THREE.ExtrudeGeometry(shape, extrudeSettings);
   var mesh = new THREE.Mesh(geometry, new THREE.MeshLambertMaterial({ color: color,wireframe:true }));
   mesh.position.set(100, 100, 0 );
   mesh.rotation.x = -Math.PI / 2;
   mesh.scale.set(s, s, s);
   scene.add(mesh);

如果我将线框属性设置为true，则对象的对角线将显示，我该如何避免它。我应该设置一些属性吗？谢谢！