当我移动鼠标时，所有子弹都在移动，而不仅仅是被射击

我正在尝试使用Pygame制作一个基本的自上而下的射击游戏。我只是想出了如何使子弹在鼠标所在的位置射击，但是现在的问题是，即使我在射击后移动鼠标，它们也会改变方向。此外，当项目符号与屏幕的左边缘碰撞时，它们不会像其他边缘一样消失。

main.py：

import pygame
import time
import math
import os
import sys
import random
from classes import *

pygame.init()

width, height = (1440, 900)
win = pygame.display.set_mode((width, height), pygame.FULLSCREEN)
pygame.display.set_caption("Dungeon")
win.fill((255, 255, 255))

# Variables to do with player shooting
shotTimer = 0
bullets = []
bulletVel = 9

# Initialize classes
player = Player(50, 800, 50, 50, PLAYERSPRITE)

def main():
    run = True
    FPS = 60
    clock = pygame.time.Clock()



    while run:
        clock.tick(FPS)

        now = pygame.time.get_ticks()

        mousex, mousey = pygame.mouse.get_pos()

        # Creates the player's bullets
        def shoot():
            global shotTimer

            if now - shotTimer >= player.cooldown:
                bullets.append(Projectile(round(player.x + player.width // 2), round(player.y + player.height // 2), 6))
                shotTimer = now

        def playerBulletUpdates():
            for bullet in bullets:
                if bullet.x >= 0 and bullet.x <= width:
                    if bullet.y >= 0 and bullet.y <= height:
                        global bulletVel

                        xDiff = mousex - player.x
                        yDiff = mousey - player.y

                        angle = math.atan2(yDiff, xDiff)

                        changeX = math.cos(angle) * bulletVel
                        changeY = math.sin(angle) * bulletVel

                        bullet.x += changeX
                        bullet.y += changeY
                    else:
                        bullets.pop(bullets.index(bullet))

        def bulletAngle():
            global bulletVel

            xDiff = mousex - player.x
            yDiff = mousey - player.y

            angle = math.atan2(yDiff, xDiff)

            changeX = int(math.cos(angle) * bulletVel)
            changeY = int(math.sin(angle) * bulletVel)

            bullet.x += changeX
            bullet.y += changeY

        def updateScreen():
            win.fill((255, 255, 255))
            player.draw(win)

            for bullet in bullets:
                bullet.draw(win)

            playerBulletUpdates()

            pygame.display.update()

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False

        keys = pygame.key.get_pressed()

        if keys[pygame.K_w] and player.y  >= 0: # UP
            player.y += -player.walkSpeed

        if keys[pygame.K_s] and player.y + player.walkSpeed + player.height <= height: # DOWN
            player.y += player.walkSpeed

        if keys[pygame.K_a] and player.x >= 0: #LEFT
            player.x += -player.walkSpeed

        if keys[pygame.K_d] and player.x + player.walkSpeed + player.width <= width: # RIGHT
            player.x += player.walkSpeed

        if pygame.mouse.get_pressed()[0]:
            shoot()

        updateScreen()

main()

classes.py：

import pygame
import math
import os

pygame.init()

width, height = (1440, 900)
win = pygame.display.set_mode((width, height), pygame.FULLSCREEN)

# Import Sprites
PLAYERSPRITE = pygame.image.load(os.path.join("assets", "gunner_class.png"))
BULLETSPRITE = pygame.image.load(os.path.join("assets", "bullet.png"))

class Player:
    def __init__(self, x, y, width, height, img):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.img = img
        self.walkSpeed = 5
        self.cooldown = 100

    def draw(self, window):
        window.blit(PLAYERSPRITE, (self.x, self.y))

class Projectile:
    def __init__(self, x, y, radius):
        self.x = x
        self.y = y
        self.radius = radius

    def draw(self, window):
            # pygame.draw.circle(window, self.color, (self.x, self.y), self.radius)
            window.blit(BULLETSPRITE, (self.x, self.y))