Re: [pygame] get all sprites?

[Pete Shinners <pete@shinners.org>]

Gerrit Holl wrote:
> I have a 'Person' object, a subclass of Sprite, which should 'fall' (go
> down) if no 'Wall' object (also a subclass of Sprite) is immediatly below.
> I do have a group of all wall objects, but in a different module. Is it
> necessary to give the 'falling' method of the Person instance (which checks
> whether to fall or not) a Group instance containing all walls, or is there a
> function which returns a Group instance containing *all* sprites (which I can
> loop over to check for walls)?
you are correct, there is no way to do this. you are definitely on the 
right track by using multiple groups. and each sprite can be a member of 
multiple groups.

one of the nice benefits of using the groups properly is that there is 
no need to check through 'all' sprites looking for certain types. you 
can keep a group of exactly what you want and only examine them. this 
works faster in python, since there is no need to iterate and examine 
sprites that will not be needed.

of course, the tradeoff is that you end up needing to do a bit of 
management yourself. but the benefit is you can take it even further. if 
your "walls" are divided into logical areas, you could create subgroups 
for each wall area. then you only need to test the player collision 
against the area he is in.

if you look at the 'aliens' example, you see that for each type of 
sprite there is actually a class attribute listing the different groups 
the class instance should belong to. by doing it that way, you can just 
create instances of sprites anytime you want, and it will automatically 
know which groups to become a member of. that is probably easier than 
keeping a list of groups around everytime you want to create a new 
instance of a sprite.

sorry there's no quick and easy answer there. good luck with those 
platforms though!



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