Scaling a sprite in main loop

Question

I want to create a game where circles are generated randomly over the surface and start to grow. When 2 circles touch each other the game ends. So, everything is working except the resizing of the sprite during a loop. When I use transform.scale I get something like this:

Resizing using "transform.scale

Then I found transform.smoothscale in the doc. I used changed my code to use this and then it looked like this:

Resizing using "transform.smoothscale"

I also tried to use Rect.inflate but this did nothing to my sprite. And I tried Rect.infalte_ip and if I use this, the sprite won't grow it is more likely to move out of the frame. Any ideas on how I can make these Sprite grow in place and that they resize how they should?

class Bubbles(pygame.sprite.Sprite):
def __init__(self):
    super().__init__()
    self.image_scale = 100
    self.image_scale_factor = 1
    self.image = resources.BUBBLE_SKIN[0].convert_alpha()
    self.image = pygame.transform.scale(self.image, (self.image_scale, self.image_scale))
    self.rect = self.image.get_rect()
    self.rect.centerx = (random.randrange(Settings.object_range_limit + (self.image_scale//2), (Settings.width - Settings.object_range_limit - self.image_scale)))
    self.rect.centery = (random.randrange(Settings.object_range_limit + (self.image_scale//2), (Settings.height - Settings.object_range_limit - self.image_scale)))

    self.growth_rate = random.randint(1, 4)

def update(self):
    self.image_scale += self.growth_rate
    self.image = pygame.transform.scale(self.image, (self.image_scale, self.image_scale))

Are you scaling the original sprite or are you gradually scaling the sprite? — Rabbid76, Jan 29 '21 at 15:09
I saved the image of the sprite in "self.image". And i used this variable to scale the image. — Lilin20, Jan 29 '21 at 15:10
Do you continuously something like `self.image`= pygame.trasnform.smoothscale(self.image, ...)`? — Rabbid76, Jan 29 '21 at 15:12

Rabbid76 · Accepted Answer · 2021-01-29T15:24:44.267

0

You must scale the original sprite, instead of gradually scaling the sprite. Every time you scale the sprint, the quality degrades. If you scale the sprite gradually, the quality gets worse and worse. Store the sprite to an attribute orignal_image and scale the orignal_image.

If you want to scale the image by the center of the image, you must update the rect attribute after scaling the image with the new image size.
See How do I scale a PyGame image (Surface) with respect to its center?

class Bubbles(pygame.sprite.Sprite):
    def __init__(self):
        # [...]
    
        self.image = resources.BUBBLE_SKIN[0].convert_alpha()
        self.image = pygame.transform.scale(
            self.image, (self.image_scale, self.image_scale))

        self.original_image =  self.image

    def update(self):
        self.image_scale += self.growth_rate
        self.image = pygame.transform.scale(
            self.original_image, (self.image_scale, self.image_scale))

        self.rect = self.image.get_rect(center = self.rect.center)

edited Jan 29 '21 at 15:24

answered Jan 29 '21 at 15:14

Rabbid76

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Thanks that worked so far. And is there a way to fix my other problem that i stated in my question regarding the "resizing in place"? – Lilin20 Jan 29 '21 at 15:17
@Lilin20 I have no idea what you are talking about. Your question is unclear. Do you want to set an initial scale? – Rabbid76 Jan 29 '21 at 15:19
Sorry for being unclear. So when i scale the sprite now, it works and it does not deform. But while it scales, the sprite moves to my bottom right corner. – Lilin20 Jan 29 '21 at 15:21
@Lilin20 I've extended the answer. – Rabbid76 Jan 29 '21 at 15:25

Scaling a sprite in main loop

1 Answers1