C Specification

The XrFrameState structure is defined as:

typedef struct XrFrameState {
    XrStructureType    type;
    void*              next;
    XrTime             predictedDisplayTime;
    XrDuration         predictedDisplayPeriod;
    XrBool32           shouldRender;
} XrFrameState;

Members

Member Descriptions
  • type is the XrStructureType of this structure.

  • next is NULL or a pointer to the next structure in a structure chain. No such structures are defined in core OpenXR.

  • predictedDisplayTime is the anticipated display XrTime for the next application-generated frame.

  • predictedDisplayPeriod is the XrDuration of the display period for the next application-generated frame, for use in predicting display times beyond the next one.

  • shouldRender is XR_TRUE if the application should render its layers as normal and submit them to xrEndFrame. When this value is XR_FALSE, the application should avoid heavy GPU work where possible, for example by skipping layer rendering and then omitting those layers when calling xrEndFrame.

Description

XrFrameState describes the time at which the next frame will be displayed to the user. predictedDisplayTime must refer to the midpoint of the interval during which the frame is displayed. The runtime may report a different predictedDisplayPeriod from the hardware’s refresh cycle.

For any frame where shouldRender is XR_FALSE, the application should avoid heavy GPU work for that frame, for example by not rendering its layers. This typically happens when the application is transitioning into or out of a running session, or when some system UI is fully covering the application at the moment. As long as the session is running, the application should keep running the frame loop to maintain the frame synchronization to the runtime, even if this requires calling xrEndFrame with all layers omitted.

Valid Usage (Implicit)

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.