#!/usr/bin/env python3

import numpy as np
import cv2 as cv
import glob

# Open camera
cap = cv.VideoCapture(0)
if not cap.isOpened():
    print("Cannot open camera")
    exit()

# termination criteria
criteria = (cv.TERM_CRITERIA_EPS + cv.TERM_CRITERIA_MAX_ITER, 30, 0.001)

# prepare object points, like (0,0,0), (1,0,0), (2,0,0) ....,(6,5,0)
objp = np.zeros((6*7,3), np.float32)
objp[:,:2] = np.mgrid[0:7,0:6].T.reshape(-1,2)

# Arrays to store object points and image points from all the images.
objpoints = [] # 3d point in real world space
imgpoints = [] # 2d points in image plane.
images = glob.glob('*.jpg')

while True:
    # Capture frame-by-frame
    ret, frame = cap.read()
    # if frame is read correctly ret is True
    if not ret:
        print("Can't receive frame (stream end?). Exiting ...")
        break
    # Our operations on the frame come here
    grey = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)

    # Find the chess board corners
    ret, corners = cv.findChessboardCorners(grey, (7,6), None)

    if ret == True:
        objpoints.append(objp)
        print( "Found corners", corners)
        corners2 = cv.cornerSubPix(grey,corners, (11,11), (-1,-1), criteria)
        imgpoints.append(corners)
        # Draw and display the corners
        cv.drawChessboardCorners(frame, (7,6), corners2, ret)
        cv.imshow('frame', frame)
        cv.waitKey(1500)
    else:
        print( "No image", corners)

cv.destroyAllWindows()