OpenCV VideoCapture视频捕捉无法启动，试图使用笔记本电脑相机

嘿大家所以我的教授给了我这个代码来查看使用OpenCV的视频捕捉，但这并不适合我 . proffessor能够在课堂上运行它并使用他的笔记本电脑相机，但相同的代码对我不起作用 . 这段代码有什么问题吗？或者我是否必须使用openCV使用笔记本电脑相机进行某种初始设置？任何帮助，将不胜感激 .

#include <opencv2/opencv.hpp>   //for OpenCV 3.x  
#include <opencv/highgui.h>     //for OpenCV 3.x  
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/gl.h>
#include <GL/glut.h>
#endif

#include <cstdio>

cv::VideoCapture *cap = NULL;
int width = 640;
int height = 480;
cv::Mat image;

/*------------ function displaying x,y,z coordinate system ----------*/     
void drawAxes(float length)
{
glPushAttrib(GL_POLYGON_BIT | GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT) ;

glPolygonMode(GL_FRONT_AND_BACK, GL_LINE) ;
glDisable(GL_LIGHTING) ;

glBegin(GL_LINES) ;
glColor3f(1,0,0) ;       //x: red  
glVertex3f(0,0,0) ;
glVertex3f(length,0,0);

glColor3f(0,1,0) ;       //y: blue  
glVertex3f(0,0,0) ;
glVertex3f(0,length,0);  

glColor3f(0,0,1) ;       //z: green  
glVertex3f(0,0,0) ;
glVertex3f(0,0,length);
glEnd() ;

glPopAttrib() ;
}

/*---------------- display --------------*/ 
void display()
{
glClear( GL_COLOR_BUFFER_BIT ); // clear window  
// cv::Mat stores data, has to flip it before displaying it
cv::Mat tempimage;
/*
flip(image, image, 0);  // vertically 
flip(image, image, +1); // horizontally 

// or 90 degree clock wise 
transpose(image, image);
flip(image, image, +1);

// or 90 degree counter clock wise 
transpose(image, image);
flip(image, image, 0);
*/ 
cv::flip(image, tempimage, 0);
           glDrawPixels(tempimage.size().width,tempimage.size().height,GL_BGR,GL_UNSIGNED _BYTE,tempimage.ptr());

//set viewport
glViewport(0, 0, tempimage.size().width, tempimage.size().height);

//set projection matrix using intrinsic camera params
glMatrixMode(GL_PROJECTION);
glLoadIdentity();

/*
void gluPerspective(GLdouble fovy,  GLdouble aspect,  GLdouble zNear,    GLdouble zFar);
*/  
gluPerspective(60, tempimage.size().width*1.0/tempimage.size().height, 1,   20); 

//you will have to set modelview matrix using extrinsic camera params
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
/*gluLookAt (cameraX, cameraY, cameraZ, lookAtX, lookAtY, lookAtZ, upX,   upY, upZ);
 https://www.khronos.org/registry/OpenGL-Refpages/gl2.1/xhtml/  gluLookAt.xml
*/  
gluLookAt(3, 3, 3, 0, 0, 0, 0, 1, 0);  //(upX, upY, upZ) = (0, 1, 0)   always 

 //now that the camera params have been set, draw your 3D shapes
//first, save the current matrix
glPushMatrix();
//move to the position where you want the 3D object to go
glTranslatef(0, 0, 0); //this is an arbitrary position for demonstration
//you will need to adjust your transformations to match the positions where
//you want to draw your objects(i.e. chessboard center, chessboard corners)
glutSolidTeapot(0.2);
glutSolidSphere(.3, 100, 100);
drawAxes(1.0);
glPopMatrix();


// show the rendering on the screen
glutSwapBuffers();

// post the next redisplay
glutPostRedisplay();
}

void reshape( int w, int h )
{
// set OpenGL viewport (drawable area)
glViewport( 0, 0, w, h );
}

void mouse( int button, int state, int x, int y )
{
if ( button == GLUT_LEFT_BUTTON && state == GLUT_UP )
{

}
}

void keyboard( unsigned char key, int x, int y )
{
switch ( key )
{
case 'q':
  // quit when q is pressed
  exit(0);
  break;

default:
  break;
}
}

void idle()
{
  // grab a frame from the camera
(*cap) >> image;
}

int main( int argc, char **argv )
{
  int w,h;

  if ( argc == 1 ) {
// start video capture from camera
cap = new cv::VideoCapture(0);
  } else if ( argc == 2 ) {
// start video capture from file
cap = new cv::VideoCapture(argv[1]);
  } else {
fprintf( stderr, "usage: %s [<filename>]\n", argv[0] );
return 1;
  }

  // check that video is opened
  if ( cap == NULL || !cap->isOpened() ) {
fprintf( stderr, "could not start video capture\n" );
return 1;
  }

  // get width and height
  w = (int) cap->get( CV_CAP_PROP_FRAME_WIDTH );
  h = (int) cap->get( CV_CAP_PROP_FRAME_HEIGHT );
 // On Linux, there is currently a bug in OpenCV that returns 
  // zero for both width and height here (at least for video from file)
  // hence the following override to global variable defaults: 
  width = w ? w : width;
  height = h ? h : height;

  // initialize GLUT
  glutInit( &argc, argv );
  glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE );
  glutInitWindowPosition( 20, 20 );
  glutInitWindowSize( width, height );
  glutCreateWindow( "OpenGL / OpenCV Example" );

  // set up GUI callback functions
  glutDisplayFunc( display );
  glutReshapeFunc( reshape );
  glutMouseFunc( mouse );
  glutKeyboardFunc( keyboard );
  glutIdleFunc( idle );

  // start GUI loop
  glutMainLoop();

      return 0;
    }

编辑：我想我知道这个问题 . 这是因为我正在运行虚拟机并且虚拟机没有检测到摄像头 . 但是我如何使用视频文件运行此代码？我也尝试过，但它没有用 .