Backend.XRType

class Win32PerformanceCounterExt : IStepper
{
	// Start by defining C# equivalents of OpenXR's function signatures and
	// types. This can be a bit involved, see PassthroughFBExt.cs in the SK
	// repository for a more extensive sample.
	delegate uint XR_xrConvertTimeToWin32PerformanceCounterKHR(ulong instance, long time, out long performanceCounter);
	static        XR_xrConvertTimeToWin32PerformanceCounterKHR xrConvertTimeToWin32PerformanceCounterKHR;
	const string timeExt = "XR_KHR_win32_convert_performance_counter_time";

	public bool Enabled { get; private set; }

	public Win32PerformanceCounterExt()
	{
		// OpenXR extensions must be requested before initializing StereoKit,
		// so this IStepper needs to be added _before_ `SK.Initialize`.
		if (SK.IsInitialized)
			Log.Err("OpenXR extensions must be constructed before StereoKit is initialized!");

		// At this point, we don't even know if the app will have access to
		// OpenXR, so this should _not_ be be guarded by a check for OpenXR.
		Backend.OpenXR.RequestExt(timeExt);
	}

	public bool Initialize()
	{
		// Check if we're running OpenXR, the extension is present, and all of
		// our extension functions bound properly.
		Enabled =
			Backend.XRType == BackendXRType.OpenXR &&
			Backend.OpenXR.ExtEnabled(timeExt)     &&
			LoadBindings();

		// Test it out!
		if (Enabled)
		{
			xrConvertTimeToWin32PerformanceCounterKHR(Backend.OpenXR.Instance, Backend.OpenXR.Time, out long counter);
			Log.Info($"XrTime: {counter}");
		}

		return Enabled;
	}

	// In this method, we load any functions from the extension that we care
	// about, and then report if they were loaded successfully.
	private bool LoadBindings()
	{
		xrConvertTimeToWin32PerformanceCounterKHR =
			Backend.OpenXR.GetFunction<XR_xrConvertTimeToWin32PerformanceCounterKHR>("xrConvertTimeToWin32PerformanceCounterKHR");

		return xrConvertTimeToWin32PerformanceCounterKHR != null;
	}

	// A more complicated extension might use these, but 
	public void Shutdown() { }
	public void Step() { }
}