Pygame + 精灵旋转不居中

Question

几天来我一直在努力解决这个问题。我正在尝试在其中心轴上旋转一个精灵，并且一直在参考之前关于同一问题的 post：

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

我使用的代码与之前 post 中描述的代码完全相同，并且还利用了 image_clean 属性，以便在连续旋转时不扭曲图像。当我尝试旋转我的精灵时，图像的中心在两点之间来回摆动。

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

打印语句验证行：

rot_sprite.get_rect().center = loc

似乎没有将 loc 值分配给图像中心。输出总是这样：

>>> 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)

我一直希望中心位于 (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() - 它总是会创建新矩形，并且您会在这个新矩形中更改位置，而不是在原始矩形中。稍后您会再次获得新的矩形来显示位置。

除了图像不保持位置你必须得到一次矩形并用它来保持位置。

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

Answer 2

您还必须传递精灵的矩形，因为它保存了精灵的实际位置，然后将中心坐标传递给 .get_rect 或将它们分配给新的矩形 center .如果你只是调用 .get_rect()，你会得到一个左上坐标为 (0, 0) 的矩形。

def rotate_center(image, rect, angle):
    """Rotate a Surface, maintaining position."""
    rot_img = pg.transform.rotate(image, angle)
    # Get a new rect and pass the center position of the old
    # rect, so that it rotates around the center.
    rect = rot_img.get_rect(center=rect.center)
    return rot_img, rect  # Return the new rect as well.


# In the main while loop.
turret.angle += 10
# Also pass the turret's rect which holds the position of the sprite.
image, rect = rotate_center(turret.image_clean, turret.rect, turret.angle)
turret.image = image  # Assign the new image.
turret.rect = rect  # Assign the new rect.

您也可以在精灵的 update 方法中执行此操作：

import pygame as pg


WHITE = pg.Color('white')

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

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


def main():
    pg.init()

    SCREEN_WIDTH = 640
    SCREEN_HEIGHT = 480
    size = (SCREEN_WIDTH, SCREEN_HEIGHT)
    screen = pg.display.set_mode(size)
    done = False
    clock = pg.time.Clock()

    all_sprites = pg.sprite.Group()

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

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

        all_sprites.update()

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

main()
pg.quit()

Pygame + 精灵旋转不居中

Pygame + Sprite rotation not staying centered

python

pygame

image-rotation