listener.c

This example can be found in examples\c\listener\listener.c.

This example shows how to implement the PST SDK using the PstTracker struct and how to receive data and tracker mode changes by implementing callback functions and registering them using pst_tracker_add_tracker_callbacks(). The example initializes the PST Tracker and grabs 100 datapoints. It outputs any change to the tracker mode on screen and shows how to restart the tracker when it reconnects.

In order to be able to run this example, the PST Tracker has to be initialized first. This can be done by starting the PST-Server and the PST-Client applications and making sure the calibration files have been downloaded and a tracking target is available. The tracking target can be the default Reference target or a newly trained or imported target. For more information, please see the Initialization section or check the PST Manual.

When compiling and running this example, please make sure that the required dependencies can be found by the executable (e.g. by copying the Redist directory into the build directory. When the PST SDK has been installed through the PST Software Suite installer the Redist folder can be found in the Development folder.).

 
#ifdef WIN32
#include <windows.h>
#else
#include <unistd.h>
#endif
 
/*
 * Define handler functions required to ensure a clean shutdown of the PST Tracker when the
 * application is terminated.
 */
 
static void Exithandler(int sig);
 
#ifdef WIN32
BOOL WINAPI ConsoleHandler(DWORD CEvent)
{
    Exithandler(CEvent);
    return TRUE;
}
#endif
 
/* End of handler functions */
 
#include "pstsdk_c.h"
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <signal.h>
 
/*
 * Helper function for clear printing of 4x4 matrices.
 */
static inline void PrintMatrix(float mat[16])
{
    for (int y = 0; y < 4; ++y)
    {
        for (int x = 0; x < 4; ++x)
        {
            printf("%f \t", mat[x + y * 4]);
        }
        printf("\n");
    }
}
 
/* Control variable for main loop */
static sig_atomic_t running = 1;
 
/* Flag for signaling tracker restart */
static sig_atomic_t restart = 0;
 
/* Number of data points to grab before application termination */
static const uint32_t numberOfSamplesToGrab = 100;
 
 /*
  * Implementation of a tracker data callback function.
  * The OnTrackerData() callback function receives the data as soon as it becomes
  * available and prints the tracking target pose to the command line.
  */
void OnTrackerData(const PstTrackerData* tracker_data, EPstErrorStatus status)
{
    static uint32_t samplesGrabbed = 0;
    if (samplesGrabbed++ >= numberOfSamplesToGrab)
    {
        running = 0;
    }
 
    for (int d = 0; d < tracker_data->number_of_targets; ++d)
    {
        float* mat = tracker_data->targetlist[d].pose_matrix;
        printf("Pose for %s \n", tracker_data->targetlist[d].target.name);
        PrintMatrix(mat);
    }
}
 
 /*
  * Implementation of a tracker mode callback function.
  * The OnTrackerMode() callback function receives tracking status information
  * as soon as the tracking mode changes and prints the tracking mode to the
  * command line.
  */
void OnTrackerMode(EPstTrackerMode mode)
{
    switch (mode)
    {
    case PST_MODE_TRACKING:
        printf("Tracker tracking\n");
        break;
    case PST_MODE_LOWPOWER:
        printf("Tracker paused\n");
        break;
    case PST_MODE_DISCONNECT:
        printf("Tracker disconnected\n");
        break;
    case PST_MODE_RECONNECT:
        printf("Tracker reconnected\n");
        restart = 1; // Tracker reconnects in paused state. Attempt restart.
        break;
    default:
        printf("Mode: %d\n", (int)mode);
        break;
    }
}
 
/*
 * Implement the exit handler to shut-down the PST Tracker connection on application termination.
 */
static void Exithandler(int sig)
{
    pst_sdk_shutdown();
    running = 0;
}
 
// Print the last error message.
void PrintLastErrorMessage()
{
    char* last_error_message = NULL;
    EPstErrorStatus error_status = pst_alloc_and_get_last_error_message(&last_error_message);
    if (error_status != PST_ERROR_STATUS_OK)
    {
        last_error_message = "Failed to allocate memory error.";
    }
    printf("last error message: %s \n", last_error_message);
    pst_free(last_error_message);
}
 
// Check error status and shutdown tracker upon error.
void CheckErrorCode(EPstErrorStatus status)
{
    if (status != PST_ERROR_STATUS_OK)
    {
        PrintLastErrorMessage();
        pst_sdk_shutdown();
        exit(status);
    }
}
 
int main(int argc, char *argv[])
{
    // Register the exit handler with the application
#ifdef WIN32
    SetConsoleCtrlHandler((PHANDLER_ROUTINE)ConsoleHandler, TRUE);
#else
    signal(SIGTERM, Exithandler);
    signal(SIGKILL, Exithandler);
    signal(SIGQUIT, Exithandler);
    signal(SIGINT, Exithandler);
#endif
 
    PstTracker ctracker;
 
#ifdef WIN32
    // Create an instance of the Tracker object using the default configuration path and file names.
    CheckErrorCode(pst_tracker_init(&ctracker));
#else
    // On Linux, specify the type of grabber that needs to be used as the last parameter:
    // "basler_ace" for PST HD or "basler_dart" for PST Pico
    CheckErrorCode(pst_tracker_init4(&ctracker, "", "config.cfg", "models.db", argv[1]));
#endif
 
    // Make sure to initialize the PstCameraURLs with ::pst_camera_urls_init before using pst_tracker_get_uncalibrated_camera_urls function.
    PstCameraURLs urls;
    pst_camera_urls_init(&urls);
    
    CheckErrorCode(pst_tracker_get_uncalibrated_camera_urls(&ctracker, true, &urls));
    // Check if calibration information is available for all cameras. When this is not the case, provide a warning.
    if (urls.number_of_urls > 0)
    {
        printf("\nNo calibration information could be found in the configuration directory. "
                        "Please use the PST Server and PST Client application to initialize the PST Tracker and create/import a tracking target. "
                        "More information can be found in the Initialization section of the PST SDK manual and the PST Manual.\n\n");
        printf("Press enter to continue...\n");
        getchar();
        pst_camera_urls_destroy(&urls);
        return 1;
    }
 
    // Make sure to destroy PstCameraURLs after using it.
    pst_camera_urls_destroy(&urls);
 
    char* version_string;
    CheckErrorCode(pst_tracker_alloc_and_get_version_info(&ctracker, &version_string));
 
    // Print version number of the tracker server being used.
    printf("Running PST Server version %s \n", version_string);
    pst_free(version_string);
 
    // Register the OnTrackerData and the OnTrackerMode callback functions to the tracker server.
    CheckErrorCode(pst_tracker_add_tracker_callbacks(&ctracker, OnTrackerData, OnTrackerMode));
 
    printf("Put the Reference card in front of the PST in order to see tracking results.\n\n");
 
    // Start the tracker server.
    CheckErrorCode(pst_tracker_start(&ctracker));
 
    // Perform a system check to see if the tracker server is running OK and print the result.
    printf("System check: %i \n", (int)pst_tracker_system_check(&ctracker));
 
    // Set the frame rate to 30 Hz.
    CheckErrorCode(pst_tracker_set_framerate(&ctracker, 30.0));
 
    // Print the new frame rate to see if it was set correctly. Note that for PST HD and Pico
    // trackers the frame rate actually being set can differ from the value provided to SetFramerate().
    double fps;
    CheckErrorCode(pst_tracker_get_framerate(&ctracker, &fps));
    printf("Frame rate set to %f \n", fps);
 
    // Main loop, wait for auto-termination.
    while (running == 1)
    {
        // If tracker has reconnected, restart it.
        if (restart == 1)
        {
            CheckErrorCode(pst_tracker_start(&ctracker));
            restart = false;
        }
#ifdef WIN32
        Sleep(100);
#else
        usleep(100000);
#endif
    }
 
    // Unregister the OnTrackerData and the OnTrackerMode callback functions from the tracker server.
    CheckErrorCode(pst_tracker_remove_tracker_callbacks(&ctracker, OnTrackerData, OnTrackerMode));
 
    // Make sure that the connection to the PST Tracker is shut down properly.
    pst_tracker_destroy(&ctracker);
    return 0;
}