learnopencv/FacialLandmarkDetection/drawLandmarks.hpp

#ifndef _renderFace_H_
#define _renderFace_H_

using namespace cv; 
using namespace std; 

#define COLOR Scalar(255, 200,0)

// drawPolyLine draws a poly line by joining 
// successive points between the start and end indices. 
void drawPolyline
(
  Mat &im,
  const vector<Point2f> &landmarks,
  const int start,
  const int end,
  bool isClosed = false
)
{
    // Gather all points between the start and end indices
    vector <Point> points;
    for (int i = start; i <= end; i++)
    {
        points.push_back(cv::Point(landmarks[i].x, landmarks[i].y));
    }
    // Draw polylines. 
    polylines(im, points, isClosed, COLOR, 2, 16);
    
}


void drawLandmarks(Mat &im, vector<Point2f> &landmarks)
{
    // Draw face for the 68-point model.
    if (landmarks.size() == 68)
    {
      drawPolyline(im, landmarks, 0, 16);           // Jaw line
      drawPolyline(im, landmarks, 17, 21);          // Left eyebrow
      drawPolyline(im, landmarks, 22, 26);          // Right eyebrow
      drawPolyline(im, landmarks, 27, 30);          // Nose bridge
      drawPolyline(im, landmarks, 30, 35, true);    // Lower nose
      drawPolyline(im, landmarks, 36, 41, true);    // Left eye
      drawPolyline(im, landmarks, 42, 47, true);    // Right Eye
      drawPolyline(im, landmarks, 48, 59, true);    // Outer lip
      drawPolyline(im, landmarks, 60, 67, true);    // Inner lip
    }
    else 
    { // If the number of points is not 68, we do not know which 
      // points correspond to which facial features. So, we draw 
      // one dot per landamrk. 
      for(int i = 0; i < landmarks.size(); i++)
      {
        circle(im,landmarks[i],3, COLOR, FILLED);
      }
    }
    
}

#endif // _renderFace_H_