MarkerTracking Permission

[TuskAW]

File: MagicLeapMarkerTracker.cs

The MLPermission.MarkerTracking permission isn't a dangerous one, so it will be better and faster to replace the call to RequestPermissions() in the Start method with the following:

        if( !MLPermissions.CheckPermission( MLPermission.MarkerTracking ).IsOk )
        {
            RequestPermissions();
        }
        else
        {
            _permissionGranted = true;
        }