Iterating through shapes

[divisator]

Hey everybody,

I've got a method that checks a given point for a specific cpBody by iterating through all bodies of the space and comparing the positions. Unfortunately I found out that I have to call cpSpaceRemoveShape and cpShapeFree to get rid of the Sprite and the assigned shape.

Could anyone tell me how to iterate through the shapes of a space (space->activeShapes I guess) so I could compare it's body property to the given body at the specific position to find out which space belongs to that body?

Thank you very much.
Have a nice day.

[slembcke]

Code: Select all

cpSpaceHashEach(cpSpaceHash *hash, cpSpaceHashIterator func, void *data);

That function will call func() with each cpShape it contains. A faster and more robust solution would be to use the data pointer on cpBody to point to your own game object/struct. Keep a list of the attached shapes there.

[divisator]

Hey - thank you very much for your fast answer. I just tried it the way you suggested and it works - I get the shape that I want to remove ... unfortunately it crashes (BAD_ACCESS @ cpSpaceHashRemove) if I want to remove the shape...

I found this way to do it somewhere on the net:

Code: Select all

			
cpShape *b = body->data;
cpSpaceRemoveBody(space, body); 
cpBodyFree(body);
			
cpSpaceRemoveShape(space, b); 
cpShapeFree(b);

Do you have any idea, why I just can't call cpSpaceRemoveShape anyway?

Thank you very much!

[divisator]

Hmm ... I just tried it without the cpSpaceRemoveShape - only the cpShapeFree - that seems to work ... but I have no idea what it does

[divisator]

oh... oh oh ... ... forget it ... it just didn't crash directly ... ehm ... ouch ... any further suggestions how I could remove this?

[slembcke]

You can't remove or free items from the same list while you are iterating it. This is a no-no with most any data structure in any language. You'll have to make a list of the objects you want to remove and remove them separately.

[divisator]

I'm sorry - you're great ;-D ... it works (even though it's in a loop ...

Everything works fine - I just got two methods of creating shapes - and made that

body->data = shape

change only in the wrong method ... I'm an idiot ... but now it works great - I'm so happy thx

[divisator]

Oh ... correction ... for anyone who tries that ;-D ... it's not in a loop ... after that ->data change I don't need the loop anymore

[Rawlyn]

slembcke, you should give Chipmunk a slogan:
"Don't try and delete pointers that you're still iterating through, and maintain your own goddamn lists!"
Or, at least, whatever that would be in Latin

You have the patience of a saint my friend!