C Specification

The xrEndFrame function is defined as:

XrResult xrEndFrame(
    XrSession                                   session,
    const XrFrameEndInfo*                       frameEndInfo);

Parameters

Parameter Descriptions

Description

xrEndFrame may return immediately to the application. XrFrameEndInfo::displayTime should be computed using values returned by xrWaitFrame. The runtime should be robust against variations in the timing of calls to xrWaitFrame, since a pipelined system may call xrWaitFrame on a separate thread from xrBeginFrame and xrEndFrame without any synchronization guarantees.

Note

An accurate predicted display time is very important to avoid black pull-in by reprojection and to reduce motion judder in case the runtime does not implement a translational reprojection. Reprojection should never display images before the display refresh period they were predicted for, even if they are completed early, because this will cause motion judder just the same. In other words, the better the predicted display time, the less latency experienced by the user.

Every call to xrEndFrame must be preceded by a successful call to xrBeginFrame. Failure to do so must result in XR_ERROR_CALL_ORDER_INVALID being returned by xrEndFrame. XrFrameEndInfo may reference swapchains into which the application has rendered for this frame. From each XrSwapchain only one image index is implicitly referenced per frame, the one corresponding to the last call to xrReleaseSwapchainImage. However, a specific swapchain (and by extension a specific swapchain image index) may be referenced in XrFrameEndInfo multiple times. This can be used for example to render a side by side image into a single swapchain image and referencing it twice with differing image rectangles in different layers.

If no layers are provided then the display must be cleared.

XR_ERROR_LAYER_INVALID must be returned if an unknown, unsupported layer type, or NULL pointer is passed as one of the XrFrameEndInfo::layers.

XR_ERROR_LAYER_INVALID must be returned if a layer references a swapchain that has no released swapchain image.

XR_ERROR_LAYER_LIMIT_EXCEEDED must be returned if XrFrameEndInfo::layerCount exceeds XrSystemGraphicsProperties::maxLayerCount or if the runtime is unable to composite the specified layers due to resource constraints.

XR_ERROR_SWAPCHAIN_RECT_INVALID must be returned if XrFrameEndInfo::layers contains a composition layer which references pixels outside of the associated swapchain image or if negatively sized.

XR_ERROR_ENVIRONMENT_BLEND_MODE_UNSUPPORTED must be returned if XrFrameEndInfo::environmentBlendMode is not supported.

XR_ERROR_SESSION_NOT_RUNNING must be returned if the session is not running.

Note

Applications should discard frames for which xrEndFrame returns a recoverable error over attempting to resubmit the frame with different frame parameters to provide a more consistent experience across different runtime implementations.

Valid Usage (Implicit)
Return Codes
On success, this command returns
  • XR_SUCCESS

  • XR_SESSION_LOSS_PENDING

On failure, this command returns
  • XR_ERROR_VALIDATION_FAILURE

  • XR_ERROR_RUNTIME_FAILURE

  • XR_ERROR_HANDLE_INVALID

  • XR_ERROR_INSTANCE_LOST

  • XR_ERROR_SESSION_LOST

  • XR_ERROR_TIME_INVALID

  • XR_ERROR_SWAPCHAIN_RECT_INVALID

  • XR_ERROR_SESSION_NOT_RUNNING

  • XR_ERROR_POSE_INVALID

  • XR_ERROR_LAYER_LIMIT_EXCEEDED

  • XR_ERROR_LAYER_INVALID

  • XR_ERROR_ENVIRONMENT_BLEND_MODE_UNSUPPORTED

  • XR_ERROR_CALL_ORDER_INVALID

See Also

Document Notes

For more information, see the OpenXR Specification

This page is extracted from the OpenXR Specification. Fixes and changes should be made to the Specification, not directly.

Copyright (c) 2014-2021, The Khronos Group Inc.