Let Sprites with Chipmunk appear and disappear after seconds

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Let Sprites with Chipmunk appear and disappear after seconds

(9 posts) (4 voices)

Started 2 years ago by eijun
Latest reply from eijun

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eijun
Member
Hi,

Could anybody give me advice?

I want to:

1) make sprites on a layer.
2) fade them out after some seconds, and finally delete them from the layer.

Sprites are created with Chipmunk.

I know how to implement 1).

But don't know how to implement 2).

I understand sprites fade out if I set fade-out action to sprites when creating them.
However, Chipmunk objects are still remained on the layer after fade out.(they exist invisible)

I show codes for 1 for just in case:
```
Sprite *mySprite = [[Sprite spriteWithFile:@"foo.png"] retain];
[someLayer addChild: mySprite];

cpBody *myBody = cpBodyNew(100.0f, INFINITY);
myBody->p = cpv(10, 10);
myBody->v = cpv(100, 30);
cpSpaceAddBody(space, myBody);

cpShape * myShape = cpCircleShapeNew(ballBody, 20.0f, cpv(0, 0));
myShape->e = 0.8f;
myShape->u = 0.2f;
myShape->data = mySprite;
myShape->collision_type = 1;

cpSpaceAddShape(space, myShape);
cpSpaceAddCollisionPairFunc(space, 1, 1, &myCollision, myLayer);
```
Thanks in advance.
Posted 2 years ago #
pabloruiz55
Member

Hi!

I don't have my mac at hand so i can't post any code, but basically what you will want to do is:

1- create a sequence with a fadeOut and a callfunc
2- in the callfunc, remove the sprite fom the layer, and destroy the cpbody and cpshape

if you could run the fadeout then the only thing you are missing is running the callfunc after that so the sprite is really removed (since although its opacity is 0, the sprite is still there) and then destroy the chipmunk body and shape.

Also notice that you shouldn't try to destroy the chipmunk body inside your collision callback. As stated in the chipmunk documents you have to flag it and then remove it outside of the collision callback.

Posted 2 years ago #
eijun
Member
Hi pabloruiz55,

Thank you for your useful advice!

I could understand to 'create a sequence with a fadeOut and a callfunc', adding the following to my sample code:
```
[mySprite runAction:[Sequence actions:
		 [FadeOut actionWithDuration:1],
		 [CallFuncN actionWithTarget:self selector:@selector(removeSprite:)],
		 nil]];

// should I use CallFuncND instead of CallFuncN?
```
Then the called method is like this:
```
-(void) removeSprite:(id)sender {

	NSLog(@"callback called from:%@", sender);     //sender seems to be a sprite, so...

	[self removeChild:sender cleanup:YES];      // I use cocos2d v0.8.0.
}
```
Are what I've done so far correct? and Could you tell me a way to destroy cpbody and cpshape?

I'm not so hurried. Could you answer my questions whenever you have your mac with you?
Posted 2 years ago #

natanavra
Member

cpSpaceRemoveBody(space, myBody);
cpSpaceRemoveShape(space, myShape);
cpBodyFree(myBody);
cpShapeFree(myShape);

Although you should probably find a way to iterate through those...
or like take the sender as the shape... shapes have everything stored in them, e.g.:

- (void)removeAll:(cpShape *)myShape {
   [self removeChild:myShape->data cleanup:YES];
   cpSpaceRemoveBody(space, myBody);
   cpSpaceRemoveShape(space, myShape);
   cpBodyFree(myBody);
   cpShapeFree(myShape);
}

This should work pretty well I think...
I don't have my mac right now so I can't verify code but I think this should go...
Update us...

Posted 2 years ago #

eijun
Member
Hi,

I changed my code like this, but application crashes when 'cpShapeFree(shape)' got executed :
```
-(void) removeSprite:(id)sender data:(cpShape*)shape {

	[self removeChild:shape->data cleanup:YES];
	cpSpaceRemoveBody(space, shape->body);
	cpSpaceRemoveShape(space, shape);
	cpBodyFree(shape->body);
	cpShapeFree(shape);

}
```
I experimentally replaced 'cpShapeFree(shape)' with 'cpShapeDestroy(shape)' and it didn't crash.

Is this a right way?
Posted 2 years ago #
Korki696
Member

Hey eijun,
Ill step in here quickly. If i remember right cpShapeDestroy is actually empty and I beleive it actually gets called inside of cpShapeFree. Does the log say anything about the crash?
-Lars

Posted 2 years ago #
eijun
Member

Hi Korki696,

Log says nothing about the crash. Only GNU copyright messages get shown.

Posted 2 years ago #
natanavra
Member

Could you try and debug, with break points? it's possible you are removing the shape during a time step and that's causing the crash?
You should use the cpShapeFree method as it is the actuall memory releaser...
Do you have a cpSpaceStep method or not?
Maybe you are passing the data wrong?

Just trying to find the source to the problem, excuse me for the randomality..

Posted 2 years ago #
eijun
Member
Hi everybody,

Today I had a long drive from Kyoto to my hometown. It took 5 hours.

And after the long trip, I resumed my development, and my app does NOT crash!

I guess the reason is not cpSpaceFree but the way I use runAction.

#my trip might have affected to codes as well :-)

I tried two different statements:
```
[mySprite runAction:[Sequence actions:
		[CallFuncND actionWithTarget:self selector:@selector(removeSprite:data:) data:(cpShape*)myShape],
		nil]];
```
And
```
[mySprite runAction:[Sequence actions:
		[FadeOut actionWithDuration:1],
		[CallFuncND actionWithTarget:self selector:@selector(removeSprite:data:) data:(cpShape*)myShape],
		nil]];
```
The former statement crashed my app, but the latter didn't.
I guess I should have set more than 2 actions to Sequence.

# I used the former statement because I wanted visually to see mySprite released; FadeOut makes mySprite invisible so......

natanavra:

I use cpSpaceStep in -(void) step: (ccTime) delta method:
```
-(void) step: (ccTime) delta
{

	cpSpaceStep(space, 1.0f/60.0f);
	cpSpaceHashEach(space->activeShapes, &eachShape, nil);
	cpSpaceHashEach(space->staticShapes, &eachShape, nil);

}
```
Posted 2 years ago #

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