球被界线接住并粘在一起

Question

让我们考虑以下代码（中心和速度随机的球碰撞，屏幕表面边界相互碰撞）：

import pygame,sys,math

from pygame.locals import *

from random import randrange

WIDTH = 500

HEIGHT = 500

WHITE = (255,255,255)

BLUE = (0, 0, 255)

RADIUS = 10

FPS = 30

DISPLAYSURF = pygame.display.set_mode((WIDTH,HEIGHT),0,32)

TAB = []

fpsClock = pygame.time.Clock()

pygame.display.set_caption('Animation')

class Point:

    def __init__(self, x, y):

        self.x = x

        self.y = y

    def distance(self, A):

        return math.sqrt((A.x-self.x)**2 + (A.y-self.y)**2)

    def getTouple(self):

        return (self.x,self.y)

class Vector:

    def __init__(self, x, y):

        self.x = x

        self.y = y

    def norm(self):

        return math.sqrt(self.x**2 + self.y**2)

class Ball:

    def __init__(self, center, radius, velocity):

        self.center = center

        self.radius = radius

        self.velocity = velocity

    def __init__(self):

        self.radius = RADIUS

        self.center = Point(randrange(RADIUS,WIDTH-RADIUS), randrange(RADIUS,HEIGHT-RADIUS))

        vx = randrange(-5,5)

        vy = randrange(-5,5)

        while vx == 0 or vy == 0:

            vx = randrange(-5,5)

            vy = randrange(-5,5)

        self.velocity = Vector(vx,vy)

这段代码有效但不正确：有些球被边界“抓住”而其他球“粘在一起”。我认为问题出在Ball课堂方法上draw。对于如何改进该代码的任何想法，我将不胜感激。