在JointJs中，如何在元素之间建立类似于3ds max创建图的链接？

// 创建画布
var graph = new joint.dia.Graph();
var paper = new joint.dia.Paper({
  el: document.getElementById('paper'),
  model: graph,
  width: 800,
  height: 600,
});

// 创建元素
var rect1 = new joint.shapes.standard.Rectangle({
  position: { x: 100, y: 100 },
  size: { width: 100, height: 50 },
  attrs: {
    body: {
      fill: 'blue',
    },
    label: {
      text: 'Element 1',
      fill: 'white',
    },
  },
});

var rect2 = new joint.shapes.standard.Rectangle({
  position: { x: 300, y: 200 },
  size: { width: 100, height: 50 },
  attrs: {
    body: {
      fill: 'green',
    },
    label: {
      text: 'Element 2',
      fill: 'white',
    },
  },
});

// 添加元素到画布
graph.addCell(rect1);
graph.addCell(rect2);

// 创建连接
var link = new joint.dia.Link({
  source: { id: rect1.id },
  target: { id: rect2.id },
  attrs: {
    line: {
      stroke: 'red',
      strokeWidth: 2,
    },
  },
});

// 添加连接到画布
graph.addCell(link);