README.devel

Linuxtrack interface is pretty simple:

  typedef enum {
    RUNNING,
    PAUSED,
    STOPPED,
    DOWN
  }ltr_state_type;
  
  int ltr_init(char *cust_section);
  int ltr_shutdown(void);
  int ltr_suspend(void);
  int ltr_wakeup(void);
  void ltr_recenter(void);
  int ltr_get_camera_update(float *heading,
                           float *pitch,
                           float *roll,
                           float *tx,
                           float *ty,
                           float *tz,
                           unsigned int *counter);
  ltr_state_type ltr_get_tracking_state(void);
  void ltr_log_message(const char *format, ...);

Lets describe its functions in a more detailed way:

int ltr_init(char *cust_section);
  This function initializes headtracking.

  Parameter cust_section is a pointer to a string containing name of the 
  profile to be used by the application. This way user can customize the 
  headtracking for each application separately.
  
  If NULL is specified, default parameters are used.
  
  It is recomended to use unique string (like name of your application) to prevent clashes.
  
  Returns zero on success, nonzero value otherwise.

int ltr_shutdown(void);
int ltr_suspend(void);
int ltr_wakeup(void);
void ltr_recenter(void);

  These functions allow you to shutdown, suspend (temporarily stop), 
  wakeup (from suspend) and recenter the tracker.

  They are non-blocking, which means that the request will not be fulfilled 
  upon return, but it will be carried out as soon as possible.

  To check the current state, please use ltr_get_tracking_state function.

int ltr_get_camera_update(float *heading,
                          float *pitch,
                          float *roll,
                          float *tx,
                          float *ty,
                          float *tz,
                          unsigned int *counter);

  This is the main function of the linuxtrack interface.
  
  Its parameters are pointers to floats, that will contain corresponding 
  rotations and translations upon successfull return.
  
  The counter parameter is pointer to the int, that receives current camera 
  frame number.
  
  Returns zero on success, nonzero value otherwise.

typedef enum {
  RUNNING,
  PAUSED,
  STOPPED,
  DOWN
}ltr_state_type;

ltr_state_type ltr_get_tracking_state(void);

  This function returns current linuxtrack state - RUNNING means tracking is on, 
  PAUSED means tracking is suspended, STOPPED means tracker is shut down and 
  finally DOWN means that tracking was not initialized yet.

void ltr_log_message(const char *format, ...);

  This is utility function, allowing you to log messages to the linuxtrack 
  logfile. Its usage is similar to the printf function.

  Linuxtrack Hello World
==========================
Here is the small "hello world" type of program showing usage of linuxtrack interface.

#include <linuxtrack.h>
#include <stdio.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
  (void) argc;
  (void) argv;
  printf("Hello World!\n");
  //Initialize the tracking using Default profile
  ltr_init(NULL);
  //Wait for tracker initialization
  ltr_state_type state;
  int timeout = 100; //10 seconds timeout (for example firmware load...)
  while(timeout > 0){
    state = ltr_get_tracking_state();
    if((state == DOWN) || (state == STOPPED)){
      usleep(100000); //sleep 0.1s
    }else{
      break;
    }
    --timeout;
  };
  
  if(ltr_get_tracking_state() != RUNNING){
    printf("Initialization is taking too long!\n");
    return 1;
  }
  
  int i;
  float heading, pitch, roll, x, y, z;
  unsigned int counter;
  
  ltr_recenter();  
  
  for(i = 0; i < 30; ++i){
    ltr_get_camera_update(&heading, &pitch, &roll, &x, &y, &z, &counter);
    printf("%f  %f  %f\n  %f  %f  %f\n", heading, pitch, roll, x, y, z);
    usleep(100000);
  }
  
  ltr_suspend();
  sleep(2);
  ltr_wakeup();
  
  for(i = 0; i < 30; ++i){
    ltr_get_camera_update(&heading, &pitch, &roll, &x, &y, &z, &counter);
    printf("%f  %f  %f\n  %f  %f  %f\n", heading, pitch, roll, x, y, z);
    usleep(100000);
  }

  ltr_shutdown();
  return 0;
}


For details on compiling this program see the project wiki page
http://code.google.com/p/linux-track/wiki/LinuxtrackInterface