Analyzing the vector and the positional relationship between points

        Write code often encountered positional relationship between the judge and the vector point, do a simple recording, easy to use later.

First, the definition of the structure

Second, the definition judging function

def judgeDirection(startPoint, endPoint, P):
    
    tmp = (startPoint.y - endPoint.y)*P.x + (endPoint.x - startPoint.x)*P.y + startPoint.x*endPoint.y - endPoint.x*startPoint.y
    if tmp < 0:
        print("the point at the right of vector!")
    else:
        print("the point at the left of vertor")

　　Third, the test

• A situation

• Case 2