balls.py 文件源码

def collide(self, p1, p2):
        np = self.np
        dx = p1.x - p2.x
        dy = p1.y - p2.y
        elasticity = 1
        dist = np.hypot(dx, dy)
        if dist < p1.size + p2.size:
            tangent = np.arctan2(dy, dx)
            angle = 0.5 * np.pi + tangent

            angle1 = 2*tangent - p1.angle
            angle2 = 2*tangent - p2.angle
            speed1 = p2.speed*elasticity
            speed2 = p1.speed*elasticity

            (p1.angle, p1.speed) = (angle1, speed1)
            (p2.angle, p2.speed) = (angle2, speed2)

            p1.x += np.sin(angle)
            p1.y -= np.cos(angle)
            p2.x -= np.sin(angle)
            p2.y += np.cos(angle)