bred

import cv2
import numpy as np
import math

cap = cv2.VideoCapture(0)
vertices = None
area = None


def calc_box_vector(box):
    v_side = math.sqrt((box[0][0] - box[3][0]) ** 2 + (box[0][1] - box[3][1]) ** 2)
    h_side = math.sqrt((box[0][0] - box[1][0]) ** 2 + (box[0][1] - box[1][1]) ** 2)
    idx = [0, 1, 2, 3]
    if v_side < h_side:
        idx = [0, 3, 1, 2]
    return ((box[idx[0]][0] + box[idx[1]][0]) / 2, (box[idx[0]][1] + box[idx[1]][1]) / 2), (
        (box[idx[2]][0] + box[idx[3]][0]) / 2, (box[idx[2]][1] + box[idx[3]][1]) / 2)


def get_vert_angle(p1, p2, w, h):
    px1 = p1[0] - w / 2
    px2 = p2[0] - w / 2

    py1 = h - p1[1]
    py2 = h - p2[1]

    angle = 90
    if px1 != px2:
        a = float(py2 - py1) / (px2 - px1) if px2 != px1 else 0
        b = py1 - a * px1
        angle = 0
        if a != 0:
            x0 = -b / a
            y1 = 1.0
            x1 = (y1 - b) / a
            dx = x1 - x0
            tg = y1 * y1 / dx / dx
            angle = 180 * np.arctan(tg) / np.pi
            if a < 0:
                angle = 180 - angle
    return angle


T = 140

def order_box(box):
    srt = np.argsort(box[:, 1])
    btm1 = box[srt[0]]
    btm2 = box[srt[1]]

    top1 = box[srt[2]]
    top2 = box[srt[3]]

    bc = btm1[0] < btm2[0]
    btm_l = btm1 if bc else btm2
    btm_r = btm2 if bc else btm1

    tc = top1[0] < top2[0]
    top_l = top1 if tc else top2
    top_r = top2 if tc else top1

    return np.array([top_l, top_r, btm_r, btm_l])


def find_main_countour(image):
    im2, cnts, hierarchy = cv2.findContours(image, cv2.RETR_CCOMP, cv2.CHAIN_APPROX_SIMPLE)

    C = None
    if cnts is not None and len(cnts) > 0:
        C = max(cnts, key=cv2.contourArea)

    if C is None:
        return None, None

    rect = cv2.minAreaRect(C)
    box = cv2.boxPoints(rect)
    box = np.int0(box)
    box = order_box(box)
    return C, box


while 1:
    s, image = cap.read()
    h, w = image.shape[:2]

    hsv = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)
    blurred = cv2.GaussianBlur(hsv, (9, 9), 0)

    cropped = cv2.inRange(blurred,(0, 0, 0),(188, 255, 32))
    if cropped is None:
        continue
    cont, box = find_main_countour(cropped)
    if cont is None:
        continue
    p1, p2 = calc_box_vector(box)

    angle = get_vert_angle(p1, p2, w, h)
    shift = 100 * (p1[0] - w / 2) / (w / 2)

    cv2.drawContours(image, [cont], -1, (0, 0, 255), 3)
    cv2.drawContours(image, [box], 0, (255, 0, 0), 2)
    cv2.line(image, (int(p1[0]), int(p1[1])), (int(p2[0]), int(p2[1])), (0, 255, 0), 3)
    msg_a = "Angle {0}".format(int(angle))
    msg_s = "Shift {0}".format(int(shift))

    cv2.putText(image, msg_a, (10, 20), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 1)
    cv2.putText(image, msg_s, (10, 40), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 1)

    cv2.imshow("Image", image)

    ch = cv2.waitKey(5)  # ожидание кнопки для закрытия P.S. не помню какая кнопка, но ESC работает
    if ch == 27:
        break