cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   JavaWizKid
   Member

   I'm having trouble finding any topics and resources on this. Can someone point me in the right direction?

   Posted 1 year ago #
2. 

   leocck
   Member

   I'm assuming you want to make a sound when a collision event occurs.

   If that's the case, inside the collision function you must play the sound.

   Maybe you'll want to guarantee that the sound will be played only one time during a certain amount of time. In this case you'll need to control a counter, just like that:
   

   static int
   wallCollision(cpShape *a, cpShape *b, cpContact *contacts, int numContacts, cpFloat normal_coef, void *data)
   {
   	if(tCollisionSound<=0){
   		// play your sound here
   		tCollisionSound = SOUND_INTERVAL_TIME;
   	}
   	return 1;
   }

   Posted 1 year ago #
3. 

   JavaWizKid
   Member

   Is that a built in function or did you make it?

   Posted 1 year ago #
4. 

   leocck
   Member

   That's the function I've associate the collisions with walls:
   

   cpSpaceAddCollisionPairFunc(space, 1, 0, &wallCollision, NULL); // collisions with walls

   0 = body collision type
   1 = wall collision type

   Posted 1 year ago #
5. 

   JavaWizKid
   Member

   I havent done any of that, I've literally just made bodies and shapes and let Chipmunk do the rest. Now I need to add sound to the collisions. I'll have a bash at the code you've sent me. Thanks!

   Posted 1 year ago #
6. 

   JavaWizKid
   Member

   warning: Semantic Issue: Implicit declaration of function 'cpSpaceAddCollisionPairFunc' is invalid in C99

   Posted 1 year ago #
7. 

   leocck
   Member

   Are you using #import "chipmunk.h" or are you working with SpaceManager ?

   Posted 1 year ago #
8. 

   JavaWizKid
   Member

   import

   Posted 1 year ago #
9. 

   JavaWizKid
   Member

   I've added cpSpaceAddCollisionPairFunc(space, 1, 0, &wallCollision, NULL); // collisions with walls to my tick function and then declared the function in the .h file by: static int wallCollision(cpShape *a, cpShape *b, cpContact *contacts, int numContacts, cpFloat normal_coef, void *data); although its erroring wallCollision declared static but never defined.

   Posted 1 year ago #
10. 

    leocck
    Member

    The cpSpaceAddCollisionPairFunc call must be after you create the bodies (not in your tick function), and the wallCollision function must be in your .m file.

    Don't forget to associate the corresponding collision type to the shapes:
    

    shape->collision_type = 0; // example

    Posted 1 year ago #
11. 

    JavaWizKid
    Member

    Ok it is in my m file but it complains i isn't declared, do I need to do something to my .h? I've put cpSpaceAddCollisionPairFunc(space, 1, 0, &wallCollision, NULL); // collisions with walls after my bodies and shapes yet it's still complaining about C99. What is that? Use of undeclared identifier 'wallCollision'

    Posted 1 year ago #
12. 

    leocck
    Member

    Is the static function inside the implementation of your class ? That is the way I'm doing...

    Maybe this or other tutorial over how to handle chipmunk collisions could help you.

    Posted 1 year ago #
13. 

    JavaWizKid
    Member

    Thanks for that. I don't see what is wrong with where I'm putting the cpSpaceAddCollisionPairFunc(space, 1, 0, &wallCollision, NULL); // collisions with walls since it's in the same place as the tutorial.

    http://img855.imageshack.us/i/screenshot20110407at013.png/

    Posted 1 year ago #
14. 

    mobilebros
    Moderator

    That function is old... maybe pre-version 5? You want this one:

    void
    cpSpaceAddCollisionHandler(
    	cpSpace *space,
    	cpCollisionType a, cpCollisionType b,
    	cpCollisionBeginFunc begin,
    	cpCollisionPreSolveFunc preSolve,
    	cpCollisionPostSolveFunc postSolve,
    	cpCollisionSeparateFunc separate,
    	void *data
    )

    Posted 1 year ago #
15. 

    mobilebros
    Moderator

    For sounds on collisions I did something like this in Kill Timmy... it worked somewhat ok:

    static inline void soundPlay(float ff, const float max, const float total, NSString* file)
    {
    	if (ff > max)
    	{
    		//clamp
    		ff = (ff > total) ? total : ff;
    		float perc = (ff-max)/(total-max);
    		[[SimpleAudioEngine sharedEngine] playEffect:file pitch:perc pan:0.0f gain:perc];
    	}
    }
    
    void box2boxCollision(cpArbiter *arb, struct cpSpace *space, void *data)
    {
    	CP_ARBITER_GET_SHAPES(arb, b1, b2);
    
    	const float max = 850.0f;
    	const float total = 1500.0f;
    
    	float ff = cpvdistsq(b1->body->v, b2->body->v);
    	NSString *file = @"boxhit.wav";
    
    	soundCheck(ff, max, total, file);
    }

    Basically I check the difference between the velocities, make sure it's less than some maximum... do a calculation for the gain (I'm not sure why exactly I used "total" here, prob could be better). I also played with the pitch here to give it some variability.

    Posted 1 year ago #
16. 

    leocck
    Member

    Thanks @mobilebros !
    Nice piece of code !

    Posted 1 year ago #
17. 

    JavaWizKid
    Member

    Cool thanks! I's not erroring now. But how do I call wallCollision from `void
    cpSpaceAddCollisionHandler(
    cpSpace *space,
    cpCollisionType a, cpCollisionType b,
    cpCollisionBeginFunc begin,
    cpCollisionPreSolveFunc preSolve,
    cpCollisionPostSolveFunc postSolve,
    cpCollisionSeparateFunc separate,
    void *data
    );`

    Posted 1 year ago #
18. 

    JavaWizKid
    Member

    I've done cpSpaceAddCollisionHandler(space, 1, 0, &wallCollision, nil, nil, nil, self); but it now says Use of undeclared identifier 'wallCollision'.

    Posted 1 year ago #
19. 

    mobilebros
    Moderator

    well where is "wallCollision" in relationship to this cpSpaceAddCollisionHandler call? It's gotta be able to know about it, so hopefully it's above it in the same file (I'm assuming you marked it static like @leocck did)

    Posted 1 year ago #
20. 

    leocck
    Member

    In general you put the static declarations on the top of any other method (inside the class implementation however). This way the compiler will recognize your function, even if it's not declared on .h file.

    Posted 1 year ago #
21. 

    JavaWizKid
    Member

    Ok now it is saying: warning: Semantic Issue: Incompatible pointer types passing 'int (*)(cpShape *, cpShape *, cpContact *, int, cpFloat, void *)' to parameter of type 'cpCollisionBeginFunc' (aka 'cpBool (*)(cpArbiter *, struct cpSpace *, void *)')

    cpSpaceAddCollisionHandler(space, 1, 0, &wallCollision, nil, nil, nil, self);

    Posted 1 year ago #
22. 

    leocck
    Member

    Man, this is another function you know... Different parameters...
    If you take a closer look at the error message you'll see that the function is waiting for two cpShapes, not the cpSpace (this is the old function !). Please refer to the Chipmunk documentation.

    Posted 1 year ago #
23. 

    JavaWizKid
    Member

    I know, so which of the cpCollisionBeginFunc begin,
    cpCollisionPreSolveFunc preSolve,
    cpCollisionPostSolveFunc postSolve,
    cpCollisionSeparateFunc separate, is the one for wallCollision...

    If it's none of them how do I call static int wallCollision at all?

    There is nothing different between mine and his http://www.cocos2d-iphone.org/forum/topic/4567 yet mine is giving me errors...

    Posted 1 year ago #
24. 

    JavaWizKid
    Member

    Slight adjustment, now it works like a gem. Thanks
    cpSpaceAddCollisionHandler(space, 1, 0, (cpCollisionBeginFunc)wallCollision, NULL, NULL, NULL, NULL);

    Posted 1 year ago #

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