Mat bg = Mat::zeros(Size(512, 512), CV_8UC3);
  Point p1(100, 100);
  Point p2(350, 100);
  Point p3(450, 280);
  Point p4(320, 450);
  Point p5(80, 400);
  std::vector<Point> pts;
  pts.push_back(p1);
  pts.push_back(p2);
  pts.push_back(p3);
  pts.push_back(p4);
  pts.push_back(p5);

  polylines(bg, pts, true, Scalar(0, 0, 255), 2, 8, 0);
  fillPoly(bg, pts, Scalar(0, 255, 255),8, 0);

  std::vector<std::vector<Point>> contours;
  contours.push_back(pts);
  drawContours(bg, contours, -1, Scalar(255, 0, 255), 2);

  imshow("Draw_polygon", bg);

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