如何在pygame中摆脱碰撞后的物体？

import pygame
import random

# 初始化pygame
pygame.init()

# 设置窗口尺寸
screen_width = 800
screen_height = 600
screen = pygame.display.set_mode((screen_width, screen_height))
pygame.display.set_caption("Collision Example")

# 定义物体类
class Object(pygame.sprite.Sprite):
    def __init__(self, x, y, width, height, color):
        super().__init__()
        self.image = pygame.Surface([width, height])
        self.image.fill(color)
        self.rect = self.image.get_rect()
        self.rect.x = x
        self.rect.y = y
        self.velocity = [random.randint(-3, 3), random.randint(-3, 3)]

    def update(self):
        self.rect.x += self.velocity[0]
        self.rect.y += self.velocity[1]

        # 边界检测
        if self.rect.x < 0 or self.rect.x > screen_width - self.rect.width:
            self.velocity[0] = -self.velocity[0]
        if self.rect.y < 0 or self.rect.y > screen_height - self.rect.height:
            self.velocity[1] = -self.velocity[1]

# 创建物体组
all_objects = pygame.sprite.Group()

# 创建物体实例
object1 = Object(100, 100, 50, 50, (255, 0, 0))
object2 = Object(200, 200, 50, 50, (0, 255, 0))
all_objects.add(object1, object2)

# 游戏循环
running = True
clock = pygame.time.Clock()
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    # 更新物体位置
    all_objects.update()

    # 碰撞检测
    if pygame.sprite.collide_rect(object1, object2):
        # 分离碰撞的物体
        object1.rect.x += object1.velocity[0]
        object1.rect.y += object1.velocity[1]
        object2.rect.x += object2.velocity[0]
        object2.rect.y += object2.velocity[1]

    # 绘制物体
    screen.fill((255, 255, 255))
    all_objects.draw(screen)

    pygame.display.flip()
    clock.tick(60)

# 退出游戏
pygame.quit()