python - Pygame + Sprite 旋转不保持居中

Question

这个问题已经有答案了:

How do I rotate an image around its center using Pygame? (6 个回答)

已关闭 3 年前。

这几天我一直在思考这个问题。我正在尝试在其中心轴上旋转 Sprite ，并且一直在引用上一篇关于同一问题的文章:

How do I rotate an image around its center using Pygame?

我使用与上一篇文章中描述的完全相同的代码，并且还利用 image_clean 属性以免连续旋转时图像变形。当我尝试旋转 Sprite 时，图像的中心在两点之间来回振荡。

def rotate_center(image, angle):
    """rotate a Surface, maintaining position."""
    loc = image.get_rect().center  #rot_image is not defined 
    rot_img = pg.transform.rotate(image, angle)
    print('')
    print('>>> before: ' + str(rot_img.get_rect().center))
    rot_img.get_rect().center = loc
    print('>>> after: ' + str(rot_img.get_rect().center))
    return rot_img

打印语句验证该行:

rot_sprite.get_rect().center = loc

似乎没有分配 loc值到图像中心。输出总是这样的:

>>> before: (32, 32)
>>> after: (32, 32)

>>> before: (37, 37)
>>> after: (37, 37)

>>> before: (41, 41)
>>> after: (41, 41)

>>> before: (43, 43)
>>> after: (43, 43)

>>> before: (45, 45)
>>> after: (45, 45)

>>> before: (45, 45)
>>> after: (45, 45)

>>> before: (43, 43)
>>> after: (43, 43)

>>> before: (41, 41)
>>> after: (41, 41)

>>> before: (37, 37)
>>> after: (37, 37)

我总是希望中心位于 (32, 32)(我相信)。任何帮助将不胜感激。

代码:

def main():
    pg.init()

# Screen Setup
size = (SCREEN_WIDTH, SCREEN_HEIGHT)
screen = pg.display.set_mode(size)
screen_flags = screen.get_flags()
pg.display.set_caption(GAME_NAME)
done = False
clock = pg.time.Clock()

# SPRITE GROUPS
all_sprites = pg.sprite.Group()
turrets = pg.sprite.Group()

turret = Tower2((SCREEN_WIDTH/2, SCREEN_HEIGHT/2))
turrets.add(turret)
all_sprites.add(turret)

# -------- Main Program Loop -----------
while not done:
    # Process Incoming Events
    for event in pg.event.get():
        if event.type == pg.QUIT:
            done = True
        if event.type == pg.KEYDOWN:
            if event.key == pg.K_q:
                done = True
            if event.key == pg.K_f:
                if screen_flags & pg.FULLSCREEN == False:
                    screen_flags |= pg.FULLSCREEN
                    pg.display.set_mode(size, screen_flags)
                else:
                    screen_flags ^= pg.FULLSCREEN
                    pg.display.set_mode(size, screen_flags)


    turret.angle += 10
    turret.image = rotate_center(turret.image_clean, turret.angle)


    screen.fill(WHITE)
    all_sprites.draw(screen)
    pg.display.flip()
    clock.tick(15)

pg.quit()


class Tower2(pg.sprite.Sprite):
    def __init__(self, pos, image, tRange, attackSpeed=1):
        super().__init__()
        self.image = image
        self.image_clean = image
        self.rect = self.image.get_rect()
        self.rect.center = pos
        self.range = tRange
        self.attackSpeed = attackSpeed
        self.lastAttack = time.time()
        self.angle = 0

    def __iter__(self):
        return self

    def canAttack(self):
        if time.time() - self.lastAttack > self.attackSpeed:
            return True
        else:
            return False

    def rotate(self):
        pass

    def update(self):
        self.angle += 10
        self.image = pg.transform.rotate(self.image_clean, self.angle)
        self.image.get_rect().center = self.image_clean.get_rect().center



class Turret1(Tower2):
    def __init__(self, pos):    
        TOWER_WIDTH = 64
        TOWER_HEIGHT = 64
        INIT_RANGE = 200
        INIT_RATE = 1
        SPEED = 1
        tower_img = pg.image.load('imgs/test_rotate.png')
        tower_img = pg.transform.scale(tower_img, (TOWER_WIDTH, TOWER_HEIGHT))
        super().__init__(pos, tower_img, INIT_RANGE, SPEED)

Answer 1

不要一直使用get_rect() - 它总是创建新矩形，并且您在这个新矩形中更改位置，而不是在原始矩形中。然后你又得到新的矩形来显示位置。

此外，图像不能保持位置，您必须获取一次矩形并使用它来保持位置。

loc = image.get_rect().center

rot_img = pg.transform.rotate(image, angle)

# get rectangle and keep it
rot_img_rect = rot_img.get_rect()

# change position in rectangle
rot_img_rect.center = loc

# display position 
print('>>> after: ', rot_img_rect.center)

# return image and position in `rot_img_rect`
return rot_img, rot_img_rect