Question

我正在编写一个程序，打开并打开带有图像的窗口并连接到我的Android设备，用户将设备用作一种触控板来平移和放大和缩小。一切正常，但程序卡在glutMainLoop中，不会继续从设备接受数据。显然glutIdleFunc是我的问题的解决方案但是我不知道如何在我的代码中实现这个而不会出现内存错误？有人可以告诉我如何将函数放入我的代码中，以便它运行连接代码以及opengl的东西吗？

#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <string.h>
#include <strings.h>
#include <vrpn_Shared.h>
#include <vrpn_Analog.h>
#include <vector>
#include <GL/freeglut.h>
#include <imageviewer.h>

using namespace std;

int done = 0;
int accepted = 0;           // Signals that the program should exit
unsigned tracker_stride = 1;    // Every nth report will be printed


//-------------------------------------
// This section contains the data structure that holds information on
// the devices that are created.  For each named device, a remote of each
// type analog is created.

class device_info {
    public:
    char            *name;

    vrpn_Analog_Remote  *ana;

};
const unsigned MAX_DEVICES = 2;


//-------------------------------------
// This section contains the data structure that is used to determine how
// often to print a report for each sensor of each tracker.  Each element
// contains a counter that is used by the callback routine to keep track
// of how many it has skipped.  There is an element for each possible sensor.
// A new array of elements is created for each new tracker object, and a
// pointer to it is passed as the userdata pointer to the callback handlers.


class t_user_callback {
    public:
    char            t_name[vrpn_MAX_TEXT_LEN];
        vector<unsigned>    t_counts ;
};

//Callback handlers

void    VRPN_CALLBACK handle_analog (void *userdata, const vrpn_ANALOGCB a)
{
    int i;
    const char *name = (const char *)userdata;

    printf("Input from %s:\n  \n        %5.0f", name, a.channel[0]);
    for (i = 1; i < a.num_channel; i++) {
    printf(" %5.0f \n", a.channel[1]);
    }
    printf(" \n");
}




int main (int argc, char * argv [])
{

  int   print_for_tracker = 1;  // Print tracker reports?
  int   print_for_button = 1;   // Print button reports?
  int   print_for_analog = 1;   // Print analog reports?
  int   print_for_dial = 1; // Print dial reports?
  int   print_for_text = 1; // Print warning/error messages?


  device_info device_list[MAX_DEVICES];
  unsigned num_devices = 0;


  int i;

  // Parse arguments, creating objects 

  for (i = 1; i < argc; i++) {
    if (!strcmp(argv[i], "-notracker")) {
      print_for_tracker = 0;
    } else if (!strcmp(argv[i], "-nobutton")) {
      print_for_button = 0;
    } else if (!strcmp(argv[i], "-noanalog")) {
      print_for_analog = 0;
    } else if (!strcmp(argv[i], "-nodial")) {
      print_for_dial = 0;
    } else if (!strcmp(argv[i], "-notext")) {
      print_for_text = 0;

    } else if (!strcmp(argv[i], "-trackerstride")) {
      if (tracker_stride <= 0) {
      fprintf(stderr, "-trackerstride argument must be 1 or greater\n");
      return -1;
      }
    } else {    // Create a device and connect to it.
    device_info *dev;



    // Name the device and open it as everything
    dev = &device_list[num_devices];
    dev->name = argv[i];

    dev->ana = new vrpn_Analog_Remote(dev->name);


    if (print_for_analog) {
        printf(" Analog");
        dev->ana->register_change_handler(dev->name, handle_analog);
    }
    printf(".\n");
    num_devices++;
    }

  }

 // main interactive loop

  printf("Press ^C to exit.\n");
  while ( ! done ) {
      unsigned i;

      // Let all the devices do their things
      for (i = 0; i < num_devices; i++) {

      device_list[i].ana->mainloop();

      glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
    glutInitWindowSize(400,300);
    glutInitWindowPosition(200,100);
    glutCreateWindow("ImageViewer");


    init();
    glutDisplayFunc(display);
    glutMotionFunc(drag);
    glutMouseFunc(mouse);
 //   glutIdleFunc(IdleFunc);
    glutMainLoop();

      }
  }
 return 0;
}

Answer 1

如果可以管理所有输入设备，那么过剩就很好了，而且一切都是由它管理的输入事件驱动的。一旦你有非托管输入设备或非基于事件的处理，你可能想要使用除过剩之外的东西。另一种方法是在一个单独的进程（或线程）中分叉和运行异步内容。

使用glutIdleFunc来摆脱glutMainLoop？

1 个答案: