With the Windows Mixed Reality API, the user coordinate system is wrapped into a SpatialStationaryFrameOfReference.
[!TIP] A simple example can be found in the remote and player samples inside the Holographic Remoting samples github repository. Uncomment
#define ENABLE_USER_COORDINATE_SYSTEM_SAMPLEinside the SampleRemoteApp.h and SamplePlayerMain.h files to enable the sample code.
To set and update the user coordinate system, call UpdateUserSpatialFrameOfReference on the player context and pass a SpatialCoordinateSystem into it.
A SpatialCoordinateSystem can, for example, be a SpatialStationaryFrameOfReference, SpatialLocatorAttachedFrameOfReference, or a SpatialAnchor.
// In the Player app:
// Create a stationary frame of reference
winrt::Windows::Perception::Spatial::SpatialStationaryFrameOfReference spatialFrameOfReference = nullptr;
winrt::Windows::Perception::Spatial::SpatialLocator spatialLocator = winrt::Windows::Perception::Spatial::SpatialLocator::GetDefault();
if (spatialLocator != nullptr)
{
spatialFrameOfReference = spatialLocator.CreateStationaryFrameOfReferenceAtCurrentLocation(float3(0.0f, 0.0f, 0.0f), quaternion(0, 0, 0, 1), 0.0);
}
...
// Update the user coordinate system with the coordinate system of the spatial frame of reference
try
{
SpatialCoordinateSystem userCoordinateSystem = spatialFrameOfReference.CoordinateSystem();
m_playerContext.UpdateUserSpatialFrameOfReference(userCoordinateSystem);
}
catch (...)
{
}
[!NOTE] With the sample SpatialStationaryFrameOfReference,
UpdateUserSpatialFrameOfReferencehas to be called in a regular interval to avoid drifting after loss of device tracking, even if the user coordinate system has not changed!
To access the user coordinate system, call GetUserSpatialFrameOfReference on the remote context.
GetUserSpatialFrameOfReference returns a SpatialStationaryFrameOfReference, which represents the user coordinate system.
// In the Remote app:
winrt::Windows::Perception::Spatial::SpatialStationaryFrameOfReference spatialUserFrameOfReference = m_remoteContext.GetUserSpatialFrameOfReference();