Struct openxr::FrameStream

pub struct FrameStream<G: Graphics> { /* fields omitted */ }

Handle for managing frame presentation

This is a secondary interface to a Session object that exposes only the frame wait/begin/end operations. These are separated so that &mut self receivers can be used to statically guarantee that calls are synchronized as required by OpenXR, enabling a safe interface.

Example

A typical presentation loop body should look roughly as follows:

let state = frame_waiter.wait().unwrap();
let image = swapchain.acquire_image().unwrap();
swapchain.wait_image(openxr::Duration::INFINITE).unwrap();

frame_stream.begin().unwrap();

if state.should_render {
    // draw scene...
}

let (view_flags, views) = session
    .locate_views(
        openxr::ViewConfigurationType::PRIMARY_STEREO,
        state.predicted_display_time,
        world_space,
    )
    .unwrap();

// set view matrices and submit to GPU...

swapchain.release_image().unwrap();
frame_stream
    .end(
        state.predicted_display_time,
        openxr::EnvironmentBlendMode::OPAQUE,
        &[&openxr::CompositionLayerProjection::new()
            .space(world_space)
            .views(&[
                openxr::CompositionLayerProjectionView::new()
                    .pose(views[0].pose)
                    .fov(views[0].fov)
                    .sub_image(
                        openxr::SwapchainSubImage::new()
                            .swapchain(swapchain)
                            .image_array_index(0)
                            .image_rect(openxr::Rect2Di {
                                offset: openxr::Offset2Di { x: 0, y: 0 },
                                extent: view_resolution[0],
                            }),
                    ),
                openxr::CompositionLayerProjectionView::new()
                    .pose(views[1].pose)
                    .fov(views[1].fov)
                    .sub_image(
                        openxr::SwapchainSubImage::new()
                            .swapchain(swapchain)
                            .image_array_index(1)
                            .image_rect(openxr::Rect2Di {
                                offset: openxr::Offset2Di { x: 0, y: 0 },
                                extent: view_resolution[1],
                            }),
                    ),
            ])],
    )
    .unwrap();

Implementations

impl<G: Graphics> FrameStream<G>

pub fn begin(&mut self) -> Result<()>

Indicate that graphics device work is beginning

pub fn end(
    &mut self,
    display_time: Time,
    environment_blend_mode: EnvironmentBlendMode,
    layers: &[&CompositionLayerBase<'_, G>]
) -> Result<()>

Indicate that all graphics work for the frame has been submitted

layers is an array of references to any type of composition layer, e.g. CompositionLayerProjection.

pub fn end_secondary(
    &mut self,
    display_time: Time,
    environment_blend_mode: EnvironmentBlendMode,
    layers: &[&CompositionLayerBase<'_, G>],
    secondary_info: SecondaryEndInfo<'_, '_, '_, G>
) -> Result<()>

Indicate that all graphics work for the frame has been submitted

layers is an array of references to any type of composition layer, e.g. CompositionLayerProjection.

secondary_info has the same information for the secondary layer

XR_MSFT_secondary_view_configuration must be loaded and the session must have been started with begin_secondary