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The XRWebGLLayer
interface's getViewport()
method returns the XRViewport
that should be used to render the specified XRView
into the WebGL layer. For WebXR devices which use a single framebuffer for both the left and right eyes, the returned viewport represents the region of the framebuffer into which the scene should be rendered for the eye represented by the view.
Syntax
let viewport = xrWebGLLayer.getViewport(view);
Parameters
view
- An
XRView
object indicating the view for which the viewport is to be returned.
Return value
A XRViewport
object representing the viewport which will restrict drawing to the portion of the layer corresponding to the specified view
.
Exceptions
InvalidStateError
- Either the specified
view
is not in an activeXRFrame
or thatXRFrame
and theXRWebGLLayer
are not part of the same WebXR session.
Example
This example demonstrates in part what the callback for the requestAnimationFrame()
function might look like, using getViewport()
to get the viewport so that drawing can be constrained to the area set aside for the eye whose viewpoint is currently being rendered.
This works because the set of views returned by an XRViewerPose
each represent one eye's perspective on the scene. Since the framebuffer is split in half, one half for each eye, setting the WebGL viewport to match the WebXR layer's viewport will ensure that when rendering the scene for the current eye's pose, it is rendered into the correct half of the framebuffer.
<<<--- add link to appropriate section in the Cameras and views article --->>>
function drawFrame(time, frame) { let session = frame.session; let pose = frame.getViewerPose(mainReferenceSpace); if (pose) { let glLayer = session.renderState.baseLayer; gl.bindFramebuffer(gl.FRAMEBUFFER, glLayer.framebuffer); gl.clearColor(0, 0, 0, 1.0); gl.clearDepth(1.0); gl.clear(gl.COLOR_BUFFER_BIT, gl.DEPTH_COLOR_BIT); for (let view of pose.views) { let viewport = glLayer.getViewport(view); gl.viewport(viewport.x, viewport.y, viewport.width, viewport.height); /* Render the scene now */ } }
Specifications
Specification | Status | Comment |
---|---|---|
WebXR Device API The definition of 'XRWebGLLayer.getViewport()' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
getViewport() | Chrome Full support 79 | Edge Full support 79 | Firefox No support No | IE No support No | Opera No support No | Safari No support No | WebView Android No support No | Chrome Android Full support 79 | Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android Full support 11.2 |
Legend
- Full support
- Full support
- No support
- No support