进入和退出全屏

window.addEventListener("dblclick", () => {
  const fullscreenElement = document.fullscreenElement;
  // 双击全屏，退出全屏
  if (!fullscreenElement) {
    // 请求全屏的dom元素.requestFullscreen() 即可进入全屏
    renderer.domElement.requestFullscreen()
  } else {
     // 退出全屏
    document.exitFullscreen()
  }

})