改变角度后向前移动。游戏

Question

我一直在做这个关于坦克的项目（基于游戏 Tank Trouble），我想知道在更改精灵的角度后如何继续前进。另外，如果您知道我如何使子弹从墙上弹射。我将非常感谢提供的任何帮助。谢谢！

这是我的坦克和子弹：

这是游戏代码：

import sys
import pygame


class Game:

    def __init__(self):
        self.run = True
        self.screen_width = 1060
        self.screen_height = 798
        self.image = pygame.image.load("sprites/background/background1.png")
        self.image = pygame.transform.scale(self.image, (self.screen_width, self.screen_height))
        self.screen = pygame.display.set_mode((self.screen_width, self.screen_height))

        # all_sprites is used to update and draw all sprites together.
        self.all_sprites = pygame.sprite.Group()

        # for collision detection with enemies.
        self.bullet_group = pygame.sprite.Group()

        self.tank = Tank()
        self.all_sprites.add(self.tank)

        bullet = Bullet(self.tank)
        self.bullet_group.add(bullet)
        self.all_sprites.add(bullet)


    def handle_events(self):
        keys = pygame.key.get_pressed()
        self.tank.handle_events()


        if keys[pygame.K_UP]:
            self.tank.rect.centery -= 5
        if keys[pygame.K_DOWN]:
            self.tank.rect.centery += 5

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                self.run = False
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    self.run = False
                if event.key == pygame.K_SPACE:
                    bullet = Bullet(self.tank)
                    self.bullet_group.add(bullet)
                    self.all_sprites.add(bullet)

    def update(self):
        # Calls `update` methods of all contained sprites.
        self.all_sprites.update()

    def draw(self):
        self.screen.blit(self.image, (0, 0))
        self.all_sprites.draw(self.screen)  # Draw the contained sprites.
        pygame.display.update()


class Tank(pygame.sprite.Sprite):

    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load("sprites/player/player_tank.png")
        self.org_image = self.image.copy()

        # A nicer way to set the start pos with `get_rect`.
        self.rect = self.image.get_rect(center=(70, 600))

        self.angle = 0
        self.direction = pygame.Vector2(1, 0)
        self.pos = pygame.Vector2(self.rect.center)

    def handle_events(self):
        pressed = pygame.key.get_pressed()
        if pressed[pygame.K_LEFT]:
            self.angle += 3
        if pressed[pygame.K_RIGHT]:
            self.angle -= 3

        self.direction = pygame.Vector2(1, 0).rotate(-self.angle)
        self.image = pygame.transform.rotate(self.org_image, self.angle)
        self.rect = self.image.get_rect(center=self.rect.center)

class Bullet(pygame.sprite.Sprite):

    def __init__(self, tank):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load("sprites/bullet/bullet.png")
        self.image = pygame.transform.scale(self.image, (16, 16))
        self.rect = self.image.get_rect()
        self.rect.centerx = tank.rect.centerx + 3 # How much pixels from tank turret on x axis
        self.rect.centery = tank.rect.centery - 25 # How much pixels from tank turret on y axis

    def update(self):
        self.rect.y -= 10  # Move up 10 pixels per frame.


def main():
    pygame.init()
    pygame.display.set_caption('Tank Game')
    clock = pygame.time.Clock()
    game = Game()

    while game.run:
        game.handle_events()
        game.update()
        game.draw()
        clock.tick(60)


if __name__ == '__main__':
    main()
    pygame.quit()
    sys.exit()

Answer 1

要使坦克向所面对的方向移动，请编写一个方法，该方法根据velocity 参数和self.angle 属性计算方向向量。 nagle 和速度由Polar coordinats 定义一个向量。
将向量添加到它的当前位置 (self.pos)。最后按位置更新self.rect属性：

class Tank(pygame.sprite.Sprite):
    # [...]

    def move(self, velocity):
        direction = pygame.Vector2(0, velocity).rotate(-self.angle)
        self.pos += direction
        self.rect.center = round(self.pos[0]), round(self.pos[1])

当 up 或 down 被按下时调用该方法：

class Game:
    # [...]

    def handle_events(self):
        # [...]

        if keys[pygame.K_UP]:
            self.tank.move(-5)
        if keys[pygame.K_DOWN]:
            self.tank.move(5)

子弹的运动方向可以类似地计算：

class Bullet(pygame.sprite.Sprite):

    def __init__(self, tank):
        #[...]

        self.rect = self.image.get_rect()
        self.angle = tank.angle
        self.pos = pygame.Vector2(tank.pos)
        self.rect.center = round(self.pos.x), round(self.pos.y)
        self.direction = pygame.Vector2(0, -10).rotate(-self.angle)

    def update(self):
        self.pos += self.direction
        self.rect.center = round(self.pos[0]), round(self.pos[1])

---

要让子弹反弹，你必须在子弹击中边界时反映方向：

class Bullet(pygame.sprite.Sprite):
    # [...]

    def update(self):
        self.pos += self.direction
        self.rect.center = round(self.pos.x), round(self.pos.y)

        if self.rect.left < 0:
            self.direction.x *= -1
            self.rect.left = 0
            self.pos.x = self.rect.centerx
        if self.rect.right > 1060:
            self.direction.x *= -1
            self.rect.right = 1060
            self.pos.x = self.rect.centerx 
        if self.rect.top < 0:
            self.direction.y *= -1
            self.rect.top = 0
            self.pos.y = self.rect.centery
        if self.rect.bottom > 798:
            self.direction.y *= -1
            self.rect.right = 798
            self.pos.y = self.rect.centery

---