/// <summary>
/// Updates the application state once per frame.
/// </summary>
public HolographicFrame Update(HolographicFrame previousFrame)
{
// TODO: Put CPU work that does not depend on the HolographicCameraPose here.
// Apps should wait for the optimal time to begin pose-dependent work.
// The platform will automatically adjust the wakeup time to get
// the lowest possible latency at high frame rates. For manual
// control over latency, use the WaitForNextFrameReadyWithHeadStart
// API.
// WaitForNextFrameReady and WaitForNextFrameReadyWithHeadStart are the
// preferred frame synchronization APIs for Windows Mixed Reality. When
// running on older versions of the OS that do not include support for
// these APIs, your app can use the WaitForFrameToFinish API for similar
// (but not as optimal) behavior.
if (canUseWaitForNextFrameReadyAPI)
{
try
{
holographicSpace.WaitForNextFrameReady();
}
catch (NotImplementedException)
{
// Catch a specific case where WaitForNextFrameReady() is present but not implemented
// and default back to WaitForFrameToFinish() in that case.
canUseWaitForNextFrameReadyAPI = false;
}
}
else if (previousFrame != null)
{
previousFrame.WaitForFrameToFinish();
}
// Before doing the timer update, there is some work to do per-frame
// to maintain holographic rendering. First, we will get information
// about the current frame.
// The HolographicFrame has information that the app needs in order
// to update and render the current frame. The app begins each new
// frame by calling CreateNextFrame.
HolographicFrame holographicFrame = holographicSpace.CreateNextFrame();
// Get a prediction of where holographic cameras will be when this frame
// is presented.
HolographicFramePrediction prediction = holographicFrame.CurrentPrediction;
// Back buffers can change from frame to frame. Validate each buffer, and recreate
// resource views and depth buffers as needed.
deviceResources.EnsureCameraResources(holographicFrame, prediction);
#if DRAW_SAMPLE_CONTENT
if (stationaryReferenceFrame != null)
{
// Check for new input state since the last frame.
for (int i = 0; i < gamepads.Count; ++i)
{
bool buttonDownThisUpdate = (gamepads[i].gamepad.GetCurrentReading().Buttons & GamepadButtons.A) == GamepadButtons.A;
if (buttonDownThisUpdate && !gamepads[i].buttonAWasPressedLastFrame)
{
pointerPressed = true;
}
gamepads[i].buttonAWasPressedLastFrame = buttonDownThisUpdate;
}
SpatialInteractionSourceState pointerState = spatialInputHandler.CheckForInput();
SpatialPointerPose pose = null;
if (null != pointerState)
{
pose = pointerState.TryGetPointerPose(stationaryReferenceFrame.CoordinateSystem);
}
else if (pointerPressed)
{
pose = SpatialPointerPose.TryGetAtTimestamp(stationaryReferenceFrame.CoordinateSystem, prediction.Timestamp);
}
pointerPressed = false;
// When a Pressed gesture is detected, the sample hologram will be repositioned
// two meters in front of the user.
quadRendererR.PositionHologram(pose);
quadRendererL.PositionHologram(pose);
}
#endif
timer.Tick(() =>
{
//
// TODO: Update scene objects.
//
// Put time-based updates here. By default this code will run once per frame,
// but if you change the StepTimer to use a fixed time step this code will
// run as many times as needed to get to the current step.
//
#if DRAW_SAMPLE_CONTENT
quadRendererR.Update(timer);
quadRendererL.Update(timer);
#endif
});
// On HoloLens 2, the platform can achieve better image stabilization results if it has
// a stabilization plane and a depth buffer.
// Note that the SetFocusPoint API includes an override which takes velocity as a
// parameter. This is recommended for stabilizing holograms in motion.
foreach (var cameraPose in prediction.CameraPoses)
{
#if DRAW_SAMPLE_CONTENT
// The HolographicCameraRenderingParameters class provides access to set
// the image stabilization parameters.
HolographicCameraRenderingParameters renderingParameters = holographicFrame.GetRenderingParameters(cameraPose);
// SetFocusPoint informs the system about a specific point in your scene to
// prioritize for image stabilization. The focus point is set independently
// for each holographic camera. When setting the focus point, put it on or
// near content that the user is looking at.
// In this example, we put the focus point at the center of the sample hologram.
// You can also set the relative velocity and facing of the stabilization
// plane using overloads of this method.
if (stationaryReferenceFrame != null)
{
renderingParameters.SetFocusPoint(
stationaryReferenceFrame.CoordinateSystem,
new System.Numerics.Vector3(0, 0, 0)
);
}
#endif
}
// The holographic frame will be used to get up-to-date view and projection matrices and
// to present the swap chain.
return(holographicFrame);
}