python - 如何使用 pygame.USEREVENT 让敌人定期开火

Question

我最近尝试使用pygame.USEREVENT + 1和pygame.time.set_timer()让敌人 Sprite 发射子弹，但我所做的似乎都没有使敌人实际上射击任何东西。程序仍在运行，但从敌人的角度来看，实际上什么也没发生。

我怎样才能让敌人实际上向任何给定方向开火，然后最终向玩家开火？

工作代码如下:

主游戏模块:

import pygame
from constants import *
from player import Player
from Projectile import Projectile
from pygame.math import Vector2
from enemy import Enemy

pygame.init()

screen = pygame.display.set_mode([500, 500])

pygame.display.set_caption('Labyrinth')


all_sprites_list = pygame.sprite.Group()
projectiles = pygame.sprite.Group()
enemy_sprites = pygame.sprite.Group()


# Spawn player

player = Player(50, 50)
all_sprites_list.add(player)

# Spawn enemy

enemy = Enemy(150, 150)
enemy_sprites.add(enemy)



clock = pygame.time.Clock()
previous_time = pygame.time.get_ticks()
speed = 12

keymap = {
    pygame.K_LEFT : Vector2(-speed, 0),
    pygame.K_RIGHT: Vector2(speed, 0),
    pygame.K_UP:    Vector2(0, -speed),
    pygame.K_DOWN:  Vector2(0, speed)
}


done = False


# ----- Event Loop

while not done:

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True

        elif event.type == pygame.KEYDOWN:

            if event.key == pygame.K_LEFT:
                vel = Vector2(-speed, 0)
            elif event.key == pygame.K_RIGHT:
                vel = Vector2(speed, 0)
            elif event.key == pygame.K_UP:
                vel = Vector2(0, -speed)
            elif event.key == pygame.K_DOWN:
                vel = Vector2(0, speed)


    current_time = pygame.time.get_ticks()

    pressed = pygame.key.get_pressed()
    for key in keymap:
        if pressed[key]:
            if current_time - previous_time > 500:
                previous_time = current_time
                projectiles.add(Projectile(player.rect.x, player.rect.y, vel))


# ----- Game Logic

    all_sprites_list.update()
    projectiles.update()
    enemy_sprites.update()



    screen.fill(GREEN)

    all_sprites_list.draw(screen)
    projectiles.draw(screen)
    enemy_sprites.draw(screen)


    pygame.display.flip()

    clock.tick(60)

pygame.quit()

播放器模块

from constants import *
import pygame
import time
from datetime import datetime, timedelta

class Player(pygame.sprite.Sprite):


    def __init__(self, x, y):

        super().__init__()

        self.image = pygame.Surface([15, 15])
        self.image.fill(BLACK)

        self.rect = self.image.get_rect()
        self.rect.x = x
        self.rect.y = y
        self.fire_rate = 1

        self.change_x = 0
        self.change_y = 0

    def changespeed(self, x, y):
        self.change_x += x
        self.change_y += y

    def update(self):
        self.rect.x += self.change_x
        self.rect.y += self.change_y

敌人模块

from constants import *
import pygame
from Projectile import Projectile
from pygame.math import Vector2

CANSHOOT = pygame.USEREVENT + 1
pygame.time.set_timer(CANSHOOT, 2000)

speed = 12

projectiles = pygame.sprite.Group()

class Enemy(pygame.sprite.Sprite):


    def __init__(self, x, y):

        super().__init__()

        self.image = pygame.Surface([10, 10])
        self.image.fill(RED)

        self.rect = self.image.get_rect()
        self.rect.x = x
        self.rect.y = y

    def can_shoot(self):

        for event in pygame.event.get():
            if pygame.event.get(CANSHOOT):
                vel = Vector2(-speed, 0)
                projectiles.add(Projectile(self.rect.x, self.rect.y, vel))


        projectiles.update()
        projectiles.draw(screen)

射弹模块

import pygame
from constants import *
from pygame.math import Vector2

BULLET_IMG = pygame.Surface((4, 4))
BULLET_IMG.fill(RED)

class Projectile(pygame.sprite.Sprite):

    def __init__(self, x, y, vel):

        super().__init__()

        self.image = BULLET_IMG
        self.rect = self.image.get_rect()
        self.rect.x = x
        self.rect.y = y
        self.vel = Vector2(vel)


    def update(self):

        self.rect.move_ip(self.vel)

Answer 1

你的程序中永远不应该有两个事件循环 (for event in pygame.event.get():)，因为 pygame.event.get 将消耗所有事件循环队列中的事件，当您在同一帧中第二次调用它时，它将为空。

如果敌方 Sprite 应该能够独立开火，您需要为每个 Sprite 提供自己的计时器。

import pygame
from pygame.math import Vector2


class Enemy(pygame.sprite.Sprite):

    def __init__(self, x, y, projectiles):
        super().__init__()
        self.image = pygame.Surface([10, 10])
        self.image.fill(RED)
        self.rect = self.image.get_rect(topleft=(x, y))
        # The previous time when the sprite fired.
        self.previous_time = pygame.time.get_ticks()
        self.shoot_delay = 1000  # milliseconds
        self.speed = 12
        self.projectiles = projectiles

    def update(self):
        now = pygame.time.get_ticks()
        if now - self.previous_time > self.shoot_delay:
            self.previous_time = now
            vel = Vector2(self.speed, 0)
            # Add the projectile to the group.
            self.projectiles.add(Projectile(self.rect.x, self.rect.y, vel))


class Projectile(pygame.sprite.Sprite):

    def __init__(self, x, y, vel):
        super().__init__()
        self.image = BULLET_IMG
        self.rect = self.image.get_rect(topleft=(x, y))
        self.vel = Vector2(vel)

    def update(self):
        self.rect.move_ip(self.vel)


pygame.init()
screen = pygame.display.set_mode([500, 500])

RED = pygame.Color('red')
GREEN = pygame.Color(40, 100, 0)
BULLET_IMG = pygame.Surface((4, 4))
BULLET_IMG.fill(RED)

all_sprites_list = pygame.sprite.Group()
projectiles = pygame.sprite.Group()
enemy_sprites = pygame.sprite.Group()
# Pass the projectiles group to the enemy, so that
# we can add the bullets in the update method later.
enemy = Enemy(150, 150, projectiles)
enemy_sprites.add(enemy)

clock = pygame.time.Clock()

done = False
while not done:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True

    # ----- Game Logic
    all_sprites_list.update()
    projectiles.update()
    enemy_sprites.update()

    screen.fill(GREEN)
    all_sprites_list.draw(screen)
    projectiles.draw(screen)
    enemy_sprites.draw(screen)
    pygame.display.flip()
    clock.tick(60)

pygame.quit()