如何在MVS中使用OpenGL繪制實時2D圖形

Question

我正在編寫一個使用命令從硬件設備接收心音並繪制接收到的信號的代碼。 我正在使用OpenGl繪制接收到的信號。 收到完整的數據后，我便可以繪圖。 但是我希望圖形隨着接收到的數據的更新而更新。這是我的代碼：

    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，當樣本緩沖區更新時，圖形也應更新。 但是該圖是在第一次迭代中繪制的，然后什么也沒有發生。 誰能告訴我如何解決？

Answer 1

當您調用glutMainLoop時，它將繪制屏幕，​​處理窗口事件並重復調用空閑函數。 由於您現在的所有空閑功能都是要求重新繪制屏幕，​​因此它將不會從您的輸入串行端口讀取其他樣本。

在調用idle函數時，您應該嘗試從串行端口讀取並填充其他示例。