0.4);
      color: white;
    }
    #hint.show {
      display: inline-block;
    }
  </style>
</head>
<body>
  <canvas id="gl-canvas" width="512" height="512"></canvas>
  <div id="hint">+</div>
  <div>
    在画布中点击鼠标绘制图形，颜色：<input id="colorPicker" type="color" value="#ff0000">
    <button id="close">绘制</button>
  </div>
  <script src="/cad_polygon/app.js"></script>
</body>
</html>