如何在MVS中使用OpenGL绘制实时2D图形

Question

我正在编写一个使用命令从硬件设备接收心音并绘制接收到的信号的代码。 我正在使用OpenGl绘制接收到的信号。 收到完整的数据后，我便可以绘图。 但是我希望图形随着接收到的数据的更新而更新。这是我的代码：

    int num_samples = 100000;


long samples[100000];
DWORD        bytes_read    = 0;    // Number of bytes read from port


/* Function plotting func */
void draw( float x1, float x2, float y1, float y2, int N)
{
    float x, dx = 1.0/N; 
glPushMatrix(); /* GL_MODELVIEW is default */

glScalef(1.0 / (x2 - x1), 1.0 / (y2 - y1), 1.0);
glTranslatef(-x1, -y1, 0.0);
glColor3f(1.0, 1.0, 1.0);

glBegin(GL_LINE_STRIP); 
int k =0;
for(x = 0; x < num_samples; x += dx)
{
    glVertex2f(x, samples[k]);
    k=k+1;
}

glEnd();

glPopMatrix();

glFlush();
};

/* Redrawing func */
void redraw(void)
{
    glClearColor(0, 0, 0, 0);
    glClear(GL_COLOR_BUFFER_BIT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    //long buf = getBuffer(samples);
    draw(0, num_samples,-693554432, 693554432, 1);
    //  draw(func, 0, 1000,0, 5000, 1);

    glutSwapBuffers();
    //glFlush();
};

/* Idle proc. Redisplays, if called. */
void idle(void)
{
    glutPostRedisplay();
};

/* Key press processing */
void key(unsigned char c, int x, int y)
{
    if(c == 27) exit(0);
};

/* Window reashape */
void reshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0, 1, 0, 1, -1, 1);
    glMatrixMode(GL_MODELVIEW);
};
/*
long putBuffer(long[] buffer)
{
    return buffer;
}*/

 //Main function 

int j =0;
unsigned long size = 400000;

int main(int argc, char* argv[])
{
    unsigned char INBUFFER[400000];

    char OUTBUFFER[20];
    DWORD        bytes_read    = 0;    // Number of bytes read from port
    DWORD        bytes_written = 0;    // Number of bytes written to the port
    HANDLE       comport      = NULL;  // Handle COM port
 int   bStatus;
    DCB          comSettings;          // Contains various port settings
    COMMTIMEOUTS CommTimeouts;
    strcpy(&OUTBUFFER[0], "The quick brown fox jumped over the lazy dog. \n\r\0");
    // Open COM port
    if ((comport = 
         CreateFile("\\\\.\\COM44",                // open com5:
                    GENERIC_READ | GENERIC_WRITE, // for reading and writing
                    0,                            // exclusive access
                    NULL,                         // no security attributes
                    OPEN_EXISTING,              
                    FILE_ATTRIBUTE_NORMAL,
                    NULL)) == INVALID_HANDLE_VALUE)
    {
       // cout<<"Port can't be opened"<<endl;
    }
    // Set timeouts in milliseconds
//  cout<<"Port opened"<<endl;
    //DCB dcb;
    CommTimeouts.ReadIntervalTimeout         = 0; 
    CommTimeouts.ReadTotalTimeoutMultiplier  = 0; 
    CommTimeouts.ReadTotalTimeoutConstant    = 100;
    CommTimeouts.WriteTotalTimeoutMultiplier = 0;
    CommTimeouts.WriteTotalTimeoutConstant   = 100;
    bStatus = SetCommTimeouts(comport,&CommTimeouts);
    if (bStatus != 0)
    {
        // error processing code goes here
    }
    // Set Port parameters.
    // Make a call to GetCommState() first in order to fill
    // the comSettings structure with all the necessary values.
    // Then change the ones you want and call SetCommState().
    GetCommState(comport, &comSettings);
   // memset(&dcb,0,sizeof(dcb));

    comSettings.fBinary = 1;
    comSettings.fDtrControl = DTR_CONTROL_ENABLE;
    comSettings.fRtsControl = RTS_CONTROL_ENABLE;
    comSettings.fOutxCtsFlow = 1;
    comSettings.fRtsControl = DTR_CONTROL_HANDSHAKE;


    comSettings.BaudRate = 921600;
    comSettings.StopBits = ONESTOPBIT;
    comSettings.ByteSize = 8;
    comSettings.Parity   = NOPARITY;
    comSettings.fParity  = FALSE;

    bStatus = SetCommState(comport, &comSettings);
    ofstream outdata;
     outdata.open("hsm.txt"); // opens the file
   if( !outdata ) { // file couldn't be opened
      cerr << "Error: file could not be opened" << endl;
      exit(1);
   }
    if (bStatus == 0)
    {
        // error processing code goes here
    }
    int flag = 1;
    int fl =1;
    glutInit(&argc, argv);
    glutInitWindowSize(500,500);
    glutInitWindowPosition(500,200);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);


    //glutMainLoop();

  while(flag<120)
   {

        bStatus = ReadFile(comport,   // Handle
                &INBUFFER,            // Incoming data
                size,                  // Number of bytes to read
                &bytes_read,          // Number of bytes read
                NULL);
        if (bStatus != 0)
        {
            //cout<<"Error receiving"<<endl;
        }
//  long samples[100000];

 for (int i=0; i<bytes_read; i++)
 {
    if((unsigned char)INBUFFER[i]==0x99&&(unsigned char)INBUFFER[i+4]==0x99)

    {
    samples[j] = 0x00|(unsigned char)INBUFFER[i+1]<<8|(unsigned char)INBUFFER[i+2]<<16|(unsigned char)INBUFFER[i+3]<<24;
    if(samples[j]!=0)
         {
          outdata << samples[j] <<"\n";
          j++;
         }      
    }


 } 

    flag++;
    glutCreateWindow("Graph plotter");
    glutDisplayFunc(redraw);
    glutReshapeFunc(reshape);
    glutIdleFunc(idle);
    glutMainLoop();

  }
  CloseHandle(comport);
outdata.close();


 return 0;
}

基本上，当样本缓冲区更新时，图形也应更新。 但是该图是在第一次迭代中绘制的，然后什么也没有发生。 谁能告诉我如何解决？

Answer 1

当您调用glutMainLoop时，它将绘制屏幕，​​处理窗口事件并重复调用空闲函数。 由于您现在的所有空闲功能都是要求重新绘制屏幕，​​因此它将不会从您的输入串行端口读取其他样本。

在调用idle函数时，您应该尝试从串行端口读取并填充其他示例。