Draw Lane on The image with Opencv

gistfile1.txt

                // Draw Lane on The image
                cv::Mat laneOverlay = drawImg(cv::Rect(0,0,drawImg.cols, drawImg.rows)).clone();
                lane_polylines.push_back(cv::Point(topic_lane[0], topic_lane[1]));
                lane_polylines.push_back(cv::Point(topic_lane[2], topic_lane[3]));
                lane_polylines.push_back(cv::Point(topic_lane[6], topic_lane[7]));
                lane_polylines.push_back(cv::Point(topic_lane[4], topic_lane[5]));
                cv::fillConvexPoly(laneOverlay, lane_polylines, cv::Scalar(0, 255, 0), 8);
                double alpha = 0.3;
                cv::addWeighted(laneOverlay, alpha, drawImg, 1 - alpha, 0, drawImg);