Re: [pygame] Collision Detection

[Pete Shinners <pete@shinners.org>]

gumuz@looze.net wrote:
> I'm having a small arena where 4 or 5 'robottanks' are driving around. The
> sprite-rotations are generated for each tank upfront, before the game
> starts. I attached the sprite, so yu can see what it looks likes. Ofcourse
> these rotated sprites are still rectangular images.
>
> I have no experience really in writing games and I don't have a clue how
> to go about creating some descent collision detection for my little battle
> tanks :)
looking at your tank sprite (nice) it looks like you will be fine doing 
straight 'rectangle' collisions. The Rect.colliderect() method is 
probably the easiest way to do this, it just tests if two Rect objects 
overlap.

because the tanks will be rotating, it is better to keep a separate Rect 
in the tank object used for collisions. best to keep this Rect slightly 
smaller than the visible area of the tank. each time you update the tank 
position, you just center this collision Rect on the image Rect and you 
should be set to go.

class Tank:
   def __init__(self, ...):
       ...
       self.crashrect = Rect(0, 0, 20, 20)
   def update(self, ...):
       ...
       self.crashrect.center = self.rect.center

if all the objects in your game have this "crashrect" attribute, it 
should be easy to compare any two objects to see if they are 'touching'.
different sized objects will likely need different sized crashrects. 
bullets would likely only be a couple pixels.

that works good for 'projectile' style shooting. if you are going for 
something more like 'hitscan' shooting (as they are called in FPS) you 
will need to move into the realm of line intersections against the 
'crashrect' attributes.


____________________________________
pygame mailing list
pygame-users@seul.org
http://pygame.seul.org