pmath.py 文件源码

def angleOfVector(p1, v, p2):
    """
    Accepts p1,  v,  and p2 of class Point or coordinate pairs
    Returns the angle in radians between the vector v-to-p1 and vector v-to-p2
    """
    #L1=distance(p1, p2)
    #L2=distance(p1, p3)
    #L3=distance(p2, p3)
    #return math.acos((L1**2+L2**2-L3**2)/(2*L1*L2))
    p1 = dPnt(p1)
    p2 = dPnt(p2)
    angle1 = angleOfLine(v, p1)
    angle2 = angleOfLine(v, p2)
    #get the absolute angle
    angle = abs(angle1 - angle2)
    #get the smallest angle of the vector, should not be greater than a straight line
    if angle > pi:
        angle = 2*pi - angle
    return angle