Play and record navigation GPS log

Play back a previously recorded or generated GPS log as input and record a GPS log as output.

Use case

Demonstrate playback of a previously recorded or generated GPS log, as well as recording a GPS log.

How to use the sample

First, get an API key token, see the Getting Started guide.

Download the Maps & Navigation SDK for C++ archive file for Linux or Windows

Navigation is simulated along the route previously recorded or generated in the input GPS log; an output GPS log with the .gm extension is written.

How it works

1. Create an instance of Environment and set your API key token:

Environment& env = Environment::GetInstance();

//
// Project API token available at:
// https://developer.magiclane.com/api/projects
//
std::string projectApiToken = ""; //YOUR_TOKEN

2. The SDK is initialized with your API key token string and the log file path, where to write the application logs. Note that logFilePath is not initialized by default, which means that no logs are written. The logFilePath is initialized with the first command line argument, if any.

std::string logFilePath;
if ( argc > 1 )
   logFilePath = std::string(argv[1]);

env.InitSDK( projectApiToken, logFilePath.c_str() );

3. The project path is obtained, to get an absolute path to the strasbourg.nmea input GPS log file. The resources path, as defined in Environment.cpp, is the path containing the Data and Examples subdirectories.

std::string sdkResrcPath = Environment::GetResourcesPath();
std::string projectRelativePath = "\\Examples\\Maps-SDK-Examples-for-Cpp\\Examples\\RoutesAndNavigation\\PlayRecordGPSLog\\";
std::string projectAbsolutePath = sdkResrcPath + projectRelativePath;
std::string inputGPSlogFile = projectAbsolutePath + "strasbourg.nmea";

4. Create a MapViewListener, OpenGLContext with the name of the app, the name of this example in this case, and a MapView. The path for writing the output GPS log files is also specified, the gpslogs directory in this case, which is set in the same directory as the Data and Examples directories, so it should be created there before running the example.

MapViewListenerImpl listener;
auto oglContext = env.ProduceOpenGLContext("PlayRecordGPSLog");
gem::StrongPointer<gem::MapView> mapView = gem::MapView::produce(oglContext, &listener);
gem::String logsdir(sdkResrcPath + "gpslogs");

5. Create a RecorderConfiguration with Position and ImprovedPosition selected for recording in a DataTypeList:

gem::sense::DataTypeList datatypes;
datatypes.push_back(gem::sense::EDataType::Position);
datatypes.push_back(gem::sense::EDataType::ImprovedPosition);
gem::RecorderConfiguration recsrcconfig(logsdir, datatypes);

6. Set the chunk duration to be recorded to 60 sec in RecorderConfiguration, as 30 sec is the minimum. Create a DataSourcePtr using the input GPS log filename, and then create a Recorder using the recorder configuration and data source.

recsrcconfig.chunkDurationSeconds = 60;
recsrcconfig.bContinuousRecording = true;
recsrcconfig.deleteOlderThanKeepMin = false;
recsrcconfig.keepMinSeconds = 3600;
std::pair<gem::sense::DataSourcePtr, int> dataSource = gem::sense::produceLogDataSource(inputGPSlogFile.c_str());
auto rec = gem::Recorder::produce(recsrcconfig, dataSource.first);

7. Set the data source in the PositionService singleton for GPS log playback. This will move the green arrow on the map along the path it followed when the GPS log was recorded or generated.

8. Start recording the playback simulation, and start following the simulated position. This will fly the camera to the green arrow and start tracking/following the green arrow as it moves on the map.

if (dataSource.first)
{
   gem::PositionService().setDataSource(dataSource.first);
   rec.get()->startRecording();
}

WAIT_TIME_OUT(1000);

mapView->startFollowingPosition();

9. Stop recording when the window is closed to save the output GPS log file.

WAIT_UNTIL_WINDOW_CLOSE();

rec.get()->stopRecording();

C++ Examples

Maps SDK for C++ Examples can be downloaded or cloned with Git