用c++opencv打开摄像头，并读取其画面

#include <opencv2/opencv.hpp>

int main()
{
cv::VideoCapture cap(0);
if(!cap.isOpened()) // check if we succeeded
return -1;

cv::namedWindow("My Camera Feed", cv::WINDOW_NORMAL);

while(true)
{
cv::Mat frame;
cap >> frame; // get a new frame from camera

cv::imshow("My Camera Feed", frame);
if(cv::waitKey(30) >= 0) break;
}
// the camera will be deinitialized automatically in VideoCapture destructor
return 0;
}