在此页

• 句法
• 用法注意事项
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

安全上下文
此特征只可用于 安全上下文 (HTTPS)，在某些或所有 支持浏览器 .

只读 XRWebGLLayer property framebuffer is an opaque WebGLFramebuffer which is used to buffer the rendered image if the XR compositor is being used. Otherwise, this property's value is null . The opaque framebuffer is functionally nearly the same as a standard WebGL framebuffer, except for the differences covered in the section How opaque framebuffers are special 下文。

句法

let framebuffer = xrWebGLLayer.framebuffer;
					

值

A WebGLFramebuffer object representing the framebuffer into which the 3D scene is being rendered, or null 若 XR compositor is disabled for the session.

用法注意事项

How opaque framebuffers are special

The framebuffer represented by the framebuffer property is opaque. As such, its behavior is different in several ways from a standard WebGL context. These differences cause the opaque framebuffer to behave more like the default WebGL framebuffer:

• Opaque framebuffers may support 抗锯齿 , even under WebGL 1.0, which don't normally do so.
• Opaque framebuffers' attachments (buffers and the like) can't be inspected or changed. Calling functions such as framebufferTexture2D() , framebufferRenderbuffer() , deleteFramebuffer() ，或 getFramebufferAttachmentParameter() on an opaque framebuffer results in the WebGL error INVALID_OPERATION (0x0502).
• Opaque framebuffers are considered incomplete and are not available for rendering other than while executing the requestAnimationFrame() callback. Attempting to clear, draw to, or read from the framebuffer results in a WebGL INVALID_FRAMEBUFFER_OPERATION error (0x0506). Calling checkFramebufferStatus() on the WebGL context from outside the animation frame callback causes the WebGL FRAMEBUFFER_UNSUPPORTED error (0x8CDD) to be reported.
• Opaque framebuffers initialized with the depth 特性被设为 false will not have a depth buffer and will rely on the coordinates alone to determine distance.
• Opaque framebuffers initialized without specifying a stencil will not have a stencil buffer.
• Opaque framebuffers will not have an alpha channel available unless the alpha 特性为 true when creating the layer.
• The XR compositor assumes that opaque framebuffers use colors with premultiplied allpha, regardless of whether or not the WebGL context's premultipliedAlpha context attribute is set.

注意： depth and stencil properties are not required to be supported in order for a browser to be construed as having full WebGL support.

The default configuration of a new framebuffer

Upon creating a new XRWebGLLayer , its new framebuffer is initialized just like the default framebuffer for any WebGL interface:

• The color buffer is configured with its clear value set to the color (0, 0, 0, 0) (meaning transparent black).
• The depth buffer's clear value is the number 1.0.
• The stencil buffer is filled with 0.

范例

This example gets the XRWebGLLayer for a session and then passes its framebuffer into the WebGL context's bindFramebuffer() 函数。

let glLayer = xrSession.renderState.baselayer;
gl.bindFramebuffer(gl.FRAMEBUFFER, glLayer.framebuffer);
					

规范

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

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 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
framebuffer	Chrome 79	Edge 79	Firefox No	IE No	Opera No	Safari No	WebView Android No	Chrome Android 79	Firefox Android No	Opera Android No	Safari iOS No	Samsung Internet Android 11.2

图例

完整支持

完整支持

不支持

不支持

另请参阅

• WebXR 设备 API
• WebGLLayerInit
• WebGLContextAttributes

元数据

• 最后修改： Jan 13, 2020

相关话题

1. WebXR 设备 API
2. XRWebGLLayer
3. 构造函数

   1. XRWebGLLayer()
4. 特性

   1. framebuffer
   2. framebufferHeight
   3. framebufferWidth
   4. ignoreDepthValues
5. 方法

   1. getViewport()
6. 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