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import cv2
import numpy as np

cap = cv2.VideoCapture(0)

cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)

while cap.isOpened():
    ret, img = cap.read()
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    blur = cv2.GaussianBlur(gray, (5, 5), 0)
    ret, thresh1 = cv2.threshold(blur, 50, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)

    image, contours, hierarchy = cv2.findContours(thresh1, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
    drawing = np.zeros(img.shape, np.uint8)

    # 輪郭の検出
    ci, max_area = -1, 0
    for i in range(len(contours)):
        cnt = contours[i]
        area = cv2.contourArea(cnt)
        # 最大の輪郭を見つける？
        if area > max_area:
            max_area = area
            ci = i
    cnt = contours[ci]

    # 輪郭の凸包（convex hull）を求める
    hull = cv2.convexHull(cnt)

    # 輪郭の重心を求める
    # http://labs.eecs.tottori-u.ac.jp/sd/Member/oyamada/OpenCV/html/py_tutorials/py_imgproc/py_contours/py_contour_features/py_contour_features.html
    moments = cv2.moments(cnt)
    if moments['m00'] != 0:
        cx = int(moments['m10'] / moments['m00'])
        cy = int(moments['m01'] / moments['m00'])
    center = (cx, cy)
    cv2.circle(img, center, 5, [0, 0, 255], 2)

    # 最大の輪郭と凸包を描画
    cv2.drawContours(drawing, [cnt], 0, (0, 255, 0), 2)
    cv2.drawContours(drawing, [hull], 0, (0, 0, 255), 2)

    # 凹状欠損（convexity defects）の検出
    cnt = cv2.approxPolyDP(cnt, 0.01 * cv2.arcLength(cnt, True), True)
    hull = cv2.convexHull(cnt, returnPoints=False)

    # 凹状欠損の点を描画
    defects = cv2.convexityDefects(cnt, hull)
    for i in range(defects.shape[0]):
        s, e, f, d = defects[i, 0]
        start = tuple(cnt[s][0])
        end = tuple(cnt[e][0])
        far = tuple(cnt[f][0])
        dist = cv2.pointPolygonTest(cnt, center, True)
        cv2.line(img, start, end, [0, 255, 0], 2)
        cv2.circle(img, far, 5, [0, 0, 255], -1)

    cv2.imshow('input', img)
    cv2.imshow('gray', gray)
    cv2.imshow('blur', blur)
    cv2.imshow('thresh1', thresh1)
    cv2.imshow('drawing', drawing)

    k = cv2.waitKey(10)
    if k == 27:
        break