角度检测

import cv2
import math
path = 'img_2.png'
img = cv2.imread(path)
pointList = []
def mousePoint(event,x,y,flags,params):
    print(x,y)
    if event == cv2.EVENT_LBUTTONDOWN:
        size = len(pointList)
        if size != 0 and size % 3 != 0:
            cv2.line(img,tuple(pointList[round((size-1)/3)*3]),(x,y),(0,0,250),2)
        cv2.circle(img,(x,y),2,(0,0,250),cv2.FILLED)
        pointList.append([x,y])
def gradient(pt1,pt2):
    return (pt2[1]-pt1[1])/(pt2[0]-pt1[0])
def getAngle(pointList):
    pt1,pt2,pt3 = pointList[-3:]
    m1 = gradient(pt1,pt2)
    m2 = gradient(pt1,pt3)
    angR = math.atan((m1-m2)/(1+m1*m2))
    angD = round(math.degrees(angR))
    cv2.putText(img,str(angD),(pt1[0]-40,pt1[1]-20),cv2.FONT_HERSHEY_COMPLEX,1.5,(0,0,250),1)

while True:
    if len(pointList) % 3  == 0 and len(pointList) != 0:
        getAngle(pointList)
    cv2.imshow('result',img)
    cv2.setMouseCallback('result',mousePoint)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        pointList = []
        img = cv2.imread(path)