python - Pygame:使用 spritecollide() 访问碰撞 Sprite 的属性

Question

我正在构建雷电 2 风格的自上而下射击游戏。我需要知道如何在使用“spritecollide”检测到碰撞时访问敌方对象。

我需要敌方对象的原因是我可以为击中他们的每一颗子弹降低他们的能量水平。

这是我必须使用的字典:

enemyCollisions = pygame.sprite.groupcollide(shipBulletGroup, enemyGroup, True, False)

这是我的 Bullet 类:

class Bullet(Entity):
    def __init__(self, ship, angle):
        Entity.__init__(self)
        self.speed = 8
        self.level = 0
        self.image = pygame.Surface((BULLET_DIMENSIONS, BULLET_DIMENSIONS)).convert()
        self.rect = self.image.get_rect()
        self.rect.x = ship.rect.centerx
        self.rect.y = ship.rect.top
        self.angle = angle

    def update(self, enemyGroup):
        if self.rect.bottom < 0:
            self.kill()
        else:
            self.rect.y -= self.speed

这是我未完成的 Enemy 类:

class Enemy_1(Entity):
    def __init__(self):
        Entity.__init__(self)
        self.speed = (1, 1)
        self.energy = 10
        self.begin = False
        self.run = False
        self.image = pygame.Surface((WIN_W/5, WIN_H/15)).convert()
        self.image.fill((70, 70, 70))
        self.rect = self.image.get_rect()
        self.rect.centerx = WIN_W/1.333
        self.rect.y = -WIN_H/15

    def shoot(self):
        bullet_1 = Bullet(self, 270)
        bullet_2 = Bullet(self, 225)
        bullet_3 = Bullet(self, 315)

    def update(self, enemyGroup, timer):
        if timer == 300:
            self.begin = True
        elif timer == 900:
            self.run = True
        elif timer > 900 and self.rect.x > WIN_W:
            self.remove(enemyGroup)

        if self.run:
            self.rect.x += self.speed[0]
            self.rect.y += self.speed[1]
        elif self.begin:
            self.rect.y += self.speed[1]
            if self.rect.y > WIN_H/4:
                self.rect.y = WIN_H/4

        if self.energy == 0:
            self.kill()

完整程序如下:

import sys, pygame, os, random, math

from ast import literal_eval

# Force static position of screen
os.environ['SDL_VIDEO_CENTERED'] = '1'

# Constants
LEFT = 'left'
RIGHT = 'right'

BLACK = (0, 0, 0)
WHITE = (255, 255, 255)

PILL_WIDTH = 5
PILL_HEIGHT = 20

WIN_W = 500
WIN_H = 800

SHIP_WIDTH = WIN_W/15
SHIP_HEIGHT = WIN_H/15

BULLET_DIMENSIONS = 5
TIMER = 0


class Entity(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)


class Text(Entity):
    def __init__(self, text, size, color, position, font=None):
        Entity.__init__(self)
        self.color = color
        self.font = pygame.font.Font(font, size)
        self.text = text
        self.set(text, position)

    def set(self, text, position):
        self.image = self.font.render(str(text), 1, self.color)
        self.rect = self.image.get_rect()
        self.rect.move_ip(position[0]-self.rect.width/2, (position[1]-self.rect.height)/2)


class Ship(Entity):
    def __init__(self, container):
        Entity.__init__(self)
        self.speed = 5
        self.score = 0
        self.image = pygame.Surface((SHIP_WIDTH, SHIP_HEIGHT)).convert()
        self.rect = self.image.get_rect()
        self.rect.centerx = container.centerx
        self.rect.y = container.centery

    def update(self, bulletGroup):
        key = pygame.key.get_pressed()
        if key[pygame.K_w]:
            self.rect.centery -= self.speed
        if key[pygame.K_s]:
            self.rect.centery += self.speed
        if key[pygame.K_d]:
            self.rect.centerx += self.speed
        if key[pygame.K_a]:
            self.rect.centerx -= self.speed
        if key[pygame.K_SPACE]:
            if TIMER % 7 == 0:
                bullet = Bullet(self, 90, 'friend')
                bulletGroup.add(bullet)

        # Ship Movement Boundaries
        if self.rect.y < WIN_H/25:
            self.rect.y = WIN_H/25
        if self.rect.y > WIN_H - SHIP_HEIGHT:
            self.rect.y = WIN_H - SHIP_HEIGHT
        if self.rect.x < 0:
            self.rect.x = 0
        if self.rect.x > WIN_W - SHIP_WIDTH:
            self.rect.x = WIN_W - SHIP_WIDTH

class Bullet(Entity):
    def __init__(self, ship, angle, type):
        Entity.__init__(self)
        self.speed = 8
        self.level = 0
        self.image = pygame.Surface((BULLET_DIMENSIONS, BULLET_DIMENSIONS)).convert()
        self.rect = self.image.get_rect()
        self.dx = math.cos(math.radians(angle)) * self.speed
        self.dy = math.sin(math.radians(angle)) * self.speed
        self.setXY(ship, type)

    def setXY(self, ship, type):
        self.rect.x = ship.rect.centerx
        if type == 'friend':
            self.rect.y = ship.rect.top
        elif type == 'enemy':
            self.rect.y = ship.rect.bottom

    def update(self):
        if self.rect.bottom < 0:
            self.kill()
        else:
            self.rect.x -= self.dx
            self.rect.y -= self.dy
            if type == 'friend':
                self.rect.y = -self.rect.y
                self.rect.x = -self.rect.x


class Powerup(Entity):
    def __init__(self, xden, pillCount):
        Entity.__init__(self)
        self.speed = 3
        self.density = xden
        self.image = pygame.Surface((PILL_WIDTH, PILL_HEIGHT)).convert()
        self.rect = self.image.get_rect()
        self.rect = self.rect.move(100,100)

    def restart(self):
        pass

    def update(self):
        if self.rect.y > WIN_H:
            del self
        else:
            self.rect = self.rect.move((0, self.speed))


class Enemy(Entity):
    def __init__(self):
        Entity.__init__(self)
        self.begin = False
        self.run = False
        self.color = (153, 0, 76)

class Planes(Enemy):
    def __init__(self, speed, energy, size, location):
        Enemy.__init__(self)
        self.speed = speed
        self.energy = energy
        self.image = pygame.Surface(size).convert()
        self.image.fill(self.color)
        self.rect = self.image.get_rect()
        self.rect.centerx = location[0]
        self.rect.y = location[1]

    def shoot(self, enemyBulletGroup):
        bullet_1 = Bullet(self, 240, 'enemy')
        bullet_2 = Bullet(self, 270, 'enemy')
        bullet_3 = Bullet(self, 300, 'enemy')
        enemyBulletGroup.add(bullet_1, bullet_2, bullet_3)

    def update(self, enemyGroup, enemyBulletGroup):
        if TIMER == 300:
            self.begin = True
        elif TIMER == 900:
            self.run = True
        elif self.rect.x > WIN_W or self.energy == 0:
            self.kill()

        if self.run:
            self.rect.x += self.speed[0]
            self.rect.y += self.speed[1]
            if TIMER % 100 == 0:
                self.shoot(enemyBulletGroup)
        elif self.begin:
            self.rect.y += self.speed[1]
            if self.rect.y > WIN_H/4:
                self.rect.y = WIN_H/4
                if TIMER % 100 == 0:
                    self.shoot(enemyBulletGroup)

def main():

    # Initialize Everything
    pygame.init()
    global TIMER
    fps = 60
    lLeft = lRight = lUp = lDown = shoot = False
    clock = pygame.time.Clock()
    play = True
    pygame.display.set_caption('Pong')
    screen = pygame.display.set_mode((WIN_W, WIN_H), pygame.SRCALPHA)

    # Create Game Objects
    ship = Ship(pygame.rect.Rect(0, 0, WIN_W, WIN_H))
    score1 = Text("Score: " + str(ship.score), 40, BLACK, (WIN_W/2, (WIN_H/25)))
    enemy_1 = Planes((1, 1), 10, (WIN_W/5, WIN_H/15), (WIN_W/1.4, -WIN_H/15))

    # Create Groups
    powerupGroup = pygame.sprite.Group()
    shipGroup = pygame.sprite.Group()
    shipGroup.add(ship)
    textGroup = pygame.sprite.Group()
    textGroup.add(score1)
    shipBulletGroup = pygame.sprite.Group()
    enemyBulletGroup = pygame.sprite.Group()
    enemyGroup = pygame.sprite.Group()
    enemyGroup.add(enemy_1)


    # Gameplay
    while play:
        # Checks if window exit button pressed
        for event in pygame.event.get():
            if event.type == pygame.QUIT: sys.exit()
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    pygame.quit()
                    sys.exit()

        # Update
        powerupGroup.update()
        ship.update(shipBulletGroup)
        shipBulletGroup.update()
        textGroup.update()
        enemyGroup.update(enemyGroup, enemyBulletGroup)
        enemyBulletGroup.update()


        enemyCollisions = pygame.sprite.groupcollide(shipBulletGroup, enemyGroup, True, False)
        for key in enemyCollisions:
            print enemyCollisions[key].energy


        # Print Background/Sprites
        screen.fill(WHITE)
        powerupGroup.draw(screen)
        shipGroup.draw(screen)
        shipBulletGroup.draw(screen)
        textGroup.draw(screen)
        enemyGroup.draw(screen)
        enemyBulletGroup.draw(screen)

        # Print Score Bar
        hori_partition = pygame.Surface((WIN_W, 1))
        screen.blit(hori_partition, (0, WIN_H/25))

        TIMER += 1
        # Limits frames per iteration of while loop
        clock.tick(fps)
        # Writes to main surface
        pygame.display.flip()

if __name__ == "__main__":
    main()

Answer 1

pygame.sprite.groupcollide() 函数返回值为列表对象的字典:

Every Sprite inside group1 is added to the return dictionary. The value for each item is the list of Sprites in group2 that intersect.

这就是为什么在迭代返回字典时调用 print enemyCollisions[key].energy 失败的原因，因为列表对象 -- enemyCollisions[key] 的值-- 没有 energy() 方法。

要在 Python 2.X 中访问字典的所有值，您可以使用字典实例的 .itervalues() 方法。要获得每个碰撞 Sprite ，请再次迭代这些值:

enemyCollisions = pygame.sprite.groupcollide(shipBulletGroup, enemyGroup, True, False)

#iterate over all values of the enemyCollisions dict
for enemyCollisions in enemyCollisions.itervalues():

    #access all enemies which collided with an shipBullet
    for enemy in enemyCollisions:
        print enemy.energy