Pygame: How to change the size of a Rect to create

Question

This question already has an answer here:

• How do I center a surface (subsurface) around a rectangle? (scaled sprite hitbox / collision rect) 1 answer

Another problem I've recently tried tackling was adjusting the size of the player's hitbox. Here's how I tried changing the hit-box (Rect's) size:

self.pseudo_rect = self.image.get_rect()  # This is the rect from the player's image to use as a reference
self.rect = pygame.Rect((self.pseudo_rect.x,self.pseudo_rect.y), (self.pseudo_rect.width,self.pseudo_rect.height)) # This is where I used the above values to make a rect with the dimensions I want

What I've discovered after testing this was that only the width and height would change when an amount is added/subtracted from it, not the x or y values. I'm not exactly sure where to go from here. Can you tell me if there's something that I'm doing wrong, or even if there is a betterr/simpler solution to this?

Answer 1

Pygame already offers some solutions for this.

If you use pygame's collision handling, (e.g. pygame.sprite.spritecollide, pygame.sprite.groupcollide or pygame.sprite.spritecollideany), note that you can use a callback function used to calculate if two sprites are colliding (the collided argument).

The default that is used is pygame.sprite.collide_rect, but in your case, you should take a look at pygame.sprite.collide_rect_ratio:

pygame.sprite.collide_rect_ratio()
Collision detection between two sprites, using rects scaled to a ratio.
collide_rect_ratio(ratio) -> collided_callable

A callable class that checks for collisions between two sprites, using a scaled version of the sprites rects.

Is created with a ratio, the instance is then intended to be passed as a collided callback function to the *collide functions.

A ratio is a floating point number - 1.0 is the same size, 2.0 is twice as big, and 0.5 is half the size.

Here's how collide_rect_ratio is implemented.

Of course you can write such a callback function yourself if you need some custom behaviour.

So maybe you want to change the function to check if a sprite has a pseudo_rect attribute, and then use this instead of the rect attribute.

Then, in your sprite classes, you could do something like this:

self.rect = self.image.get_rect()    
self.pseudo_rect = self.rect.inflate(5, 5)

if you want to give a sprite a bigger hitbox (don't forget to set pseudo_rect's center attribute to rect.center everything you change rect).

Another way could be to give your sprites a collision_ration attribute and use it in the collision function, if set.