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• 句法
• 范例
• 规范
• 浏览器兼容性
• 相关话题

XRSystem 接口的 requestSession() 方法返回 promise which resolves to an XRSession object through which you can manage the requested type of WebXR session.

While only one immersive VR session can be active at a time, multiple inline sessions can be in progress at once.

句法

var sessionPromise = xr.requestSession(sessionMode, sessionInit)
					

参数

sessionMode

A DOMString whose value is one of those included in the XRSessionMode enum . The supported modes are:

immersive-ar

The session's output will be given exclusive access to the immersive device, but the rendered content will be blended with the real-world environment. The session's environmentBlendMode indicates the method to be used to blend the content together.

重要： immersive-ar mode is defined by the WebXR Augmented Reality Module, which is not yet stable and should not be used other than for testing and experimentation.

immersive-vr

Indicates that the rendered session will be displayed using an immersive XR device in VR mode; it is not intended to be overlaid or integrated into the surrounding environment. The environmentBlendMode is expected to be opaque if possible, but might be additive if the hardware requires it.

inline

The output is presented inline within the context of an element in a standard HTML document, rather than occupying the full visual space. Inline sessions can be presented in either mono or stereo mode, and may or may not have viewer tracking available. Inline sessions don't require special hardware and should be avalable on any 用户代理 offering WebXR API support.

sessionInit 可选

XRSessionInit object providing options to configure the new XRSession 。见 Specifying session options for details on how to configure a WebXR session.

返回值

A Promise that resolves with an XRSession object if the device and user agent support the requested mode and features.

异常

This method doesn't throw true exceptions; instead, it rejects the returned promise, passing into it a DOMException whose 名称 is one of the following:

InvalidStateError

The requested session mode is immersive-vr but there is already an immersive VR session either currently active or in the process of being set up. There can only be one immersive VR session at a time.

NotSupportedError

There is no WebXR-compatible device available, or the device does not support the specified sessionMode ; this can also be thrown if any of the required options are unsupported.

SecurityError

Permission to enter the specified XR mode is denied. This can happen for a number of reasons, which are covered in more detail in Permissions and security in WebXR 设备 API .

范例

Creating an immersive VR session

The following example calls requestSession() requesting an "immersive-vr" session. If the Promise resolves, it sets up a session and initiates the animation loop.

navigator.xr.requestSession("immersive-vr")
.then((xrSession) => {
  xrSession.addEventListener('end', onXRSessionEnded);
  // Do necessary session setup here.
  // Begin the session’s animation loop.
  xrSession.requestAnimationFrame(onXRAnimationFrame);
}).catch(function(error) {
  // "immersive-vr" sessions are not supported
  console.warn("'immersive-vr' isn't supported, or an error occurred activating VR!");
});
					

Verifying WebXR support and using a button to start VR mode

The following example shows how to use both isSessionSupported() and requestSession() . First, it checks to see if WebXR is available by verifying the existence of navigator.xr . Next, it calls isSessionSupported() , passing it the desired session option before enabling controls for entering XR. Adding controls is a necessary step because entering XR requires a user action. Finally, the onButtonClicked() method calls requestSession() using the same session option passed to isSessionSupported() .

if (navigator.xr) {
  navigator.xr.isSessionSupported('immersive-vr')
  .then((isSupported) => {
    if (isSupported) {
      immersiveButton.addEventListener('click', onButtonClicked);
      immersiveButton.innerHTML = 'Enter XR';
      immersiveButton.disabled = false;
    } else {
      console.log("WebXR doesn't support immersive-vr mode!");
    }
  });
} else {
  console.log("WebXR is not available!");
}
function onButtonClicked() {
  if (!xrSession) {
    navigator.xr.requestSession('immersive-vr')
    .then((session) => {
      xrSession = session;
      // onSessionStarted() not shown for reasons of brevity and clarity.
      onSessionStarted(xrSession);
    });
  } else {
    // Button is a toggle button.
    xrSession.end().then(() => xrSession = null);
  }
}
					

规范

规范	状态	注释
WebXR 设备 API The definition of 'requestSession()' in that specification.	工作草案	初始定义。

浏览器兼容性

更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
requestSession()	Chrome 79	Edge 79	Firefox 不支持 No	IE 不支持 No	Opera 不支持 No	Safari 不支持 No	WebView Android 不支持 No	Chrome Android 79	Firefox Android 不支持 No	Opera Android 不支持 No	Safari iOS 不支持 No	Samsung Internet Android 11.2

图例

完整支持

完整支持

不支持

不支持

实验。期望将来行为有所改变。

实验。期望将来行为有所改变。

元数据

• 最后修改： Mar 27, 2020

相关话题

1. WebXR 设备 API
2. XRSystem
3. 方法

   1. XRSystem: isSessionSupported()
   2. XRSystem: requestSession()
4. Related pages for WebXR Device API

   1. Navigator.xr
   2. WebGLRenderingContext.makeXRCompatible()
   3. XR
   4. XRBoundedReferenceSpace
   5. XRFrame
   6. XRInputSource
   7. XRInputSourceArray
   8. XRInputSourceEvent
   9. XRInputSourcesChangeEvent
   10. XRPose
   11. XRReferenceSpace
   12. XRReferenceSpaceEvent
   13. XRRenderState
   14. XRRigidTransform
   15. XRSession
   16. XRSessionEvent
   17. XRSpace
   18. XRView
   19. XRViewerPose
   20. XRViewport
   21. XRWebGLLayer