title: How to draw four points which are detected by contours using opencv python
body: <p>I need to know how do i draw lines between four points? all points are detected by contours. 
  There are four red points.as shown below  these points are detected using cv2.findContours. After I need to draw lines on each of points like a rectangle. Can someone please help me to solve this ? Also I used convexhull to do this but i couldn't sort it out. </p>
  
  <p><img src="https://i.stack.imgur.com/4bDPu.jpg" alt="enter image description here"></p>
  
  <p>here is the code that i used</p>
  
  <pre><code>ret, frame = cap.read()
  hsv = cv2.cvtColor(frame,cv2.COLOR_BGR2HSV) 
  RedMask = cv2.inRange(hsv,(0,100,100),(10,255,255))
  contours1, _ = cv2.findContours(RedMask, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE) 
  for cnt1 in contours1: 
     #area = cv2.contourArea(cnt1) 
     #Draw it 
     #cv2.drawContours(frame,[cnt],0,(255,0,0),2)
  
     hull = cv2.convexHull(cnt1)
     cv2.drawContours(frame,hull,3,(255,0,0),2)
  </code></pre>