pygame.transform.rotate不起作用

Question

The code below is a draw function of an npc class in a game I'm making in pygame (source: https://github.com/hailfire006/games/blob/master/strategy%20gamev2 ), and it all works great except for this one line

pygame.transform.rotate(self.sprite.image,angle)

which should rotate the npc towards the point it's moving to. For whatever reason, it's just not rotating. I think it might have something to do with the fact that I'm not storing the result of this function into a variable but I'm not sure.

the rest of the function:

    target = get_target(self)
    if target != 0:
        angle = math.degrees(math.atan2(self.x - target[0], self.y - target[1])) + 90
        self.sprite.image = pygame.transform.rotate(self.sprite.image,angle)
        self.shoot(target)
    if self.moving != False:
        if abs(self.x - self.moving[0]) < 3 and abs(self.y - self.moving[1]) < 3:
            self.moving = False
        else:
            self.move(self.moving)
            if target == 0:
                angle = math.degrees(math.atan2(self.x - self.moving[0], self.y - self.moving[1])) + 90
                pygame.transform.rotate(self.sprite.image,angle)
    if self.hp <= 0:
        objects.remove(self)
        return

    self.sprite.rect = self.sprite.image.get_rect()
    self.sprite.rect.topleft = [self.x - 20, self.y - 20]
    window.blit(self.sprite.image, self.sprite.rect)

Answer 1

You need to have a self._base_sprite and a self._active_sprite

Set your init code to initialise _base_sprite and then change your line from:

pygame.transform.rotate(self.sprite.image,angle)

to:

self._active_sprite = pygame.transform.rotate(self._base_sprite.image,angle)

and then blit your active sprite

The reasoning is:

• When rotating a sprite you buffer out the image so you don't lose pixels (including any alpha'd corners), which gains space
• If you rotate a rotated sprite you repeat this process
• If you keep rotating you will run out of memory
• Thus, we retain two surfaces in memory, one "base" one and one "active" one.

Additionally, your .rect adjustment code should probably be only done in your init function. You're trying to adjust the center of the sprite, I assume?

Edit: Note, this question here is highly related (and in the sidebar).