Chipmunk Physics

Posted: **Thu Mar 25, 2010 8:04 pm**

Hello there!

Firstly apologies for my first post being a question, I'm sure it becomes very annoying.

Anywho if you could help me that would be fantastc.

I'm using chipmunk 5.1.0 for my iphone and I've tried to remove the body / shape of an object when its reached a certain point on the screen (When its fallen off the bottom) I'm using this code to catch it :

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 if(ball.center.y > self.view.bounds.size.height) {
		
		 if(ball.center.y > self.view.bounds.size.height + 10) {			 
			 score_int = score_int + 1;
			 score.text = [NSString stringWithFormat:@"%d",score_int];	 
			 
			 cpSpaceRemoveBody(space, ballBody);
			 cpSpaceRemoveShape(space, ballShape);
			 
			 [ball removeFromSuperview];	
			 
		 }
	 }

When it reaches this point in the actual application though, it crashes out giving :

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Initializing Chipmunk v5.1.0 (Debug Enabled)
Compile with NDEBUG defined to disable debug mode and assert() checks
Assertion failed: (cpArrayContains(space->bodies, body)), function cpSpaceRemoveBody, file /Users/rob/Documents/Iphone Development/Basic Assign Ap/balls Up 0.25/chipmunk/cpSpace.c, line 321.

I will say I've tried removing the shape first and the body first! So I'm very sure it isn't a removal in the right order issue.

I also have a cpDataPointer warning about it being an 'invalid receiver type' but I don't think its related to the issue above. I thought it was worth mentioning though!

That occurs on this line of code :

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	if([shape->data isKindOfClass:[UIView class]]) { 
		
		[(UIView *)shape->data setCenter:CGPointMake(shape->body->p.x, 480-shape->body->p.y)];
		
	}

If you need any more information please don't hesitate to ask, but any help in this issue would be great

Posted: **Thu Mar 25, 2010 9:06 pm**

Just to add,

If I put the RemoveShape first I get :

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Initializing Chipmunk v5.1.0 (Debug Enabled)
Compile with NDEBUG defined to disable debug mode and assert() checks
Assertion failed: (cpHashSetFind(space->activeShapes->handleSet, shape->hashid, shape)), function cpSpaceRemoveShape, file /Users/rob/Documents/Iphone Development/Basic Assign Ap/balls Up 0.25/chipmunk/cpSpace.c, line 305.

Posted: **Thu Mar 25, 2010 11:05 pm**

Both of those assertions mean that you never actually added the body or shape in the first place or you are trying to remove it more than once. I think I changed those to warnings in 5.2.x, but the root problem is the same.

Posted: **Fri Mar 26, 2010 5:46 am**

Interesting,

It is interacting completely fine prior to reaching that point though, I also have it declared in a setup method which is called as soon as the application is launched :

This is in the header :

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	cpSpace *space; // Holds the space object
	cpBody *ballBody;
	cpShape *ballShape;

This is in the main :

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 // Create our ball's body with 100 mass
 // and infinite moment
	//							  mass    moment 
	ballBody = cpBodyNew(100.0, INFINITY);
	
 // Set the initial Position
				//Width, Height
	ballBody->p = cpv(60, 250);
	
 // Add the body to the space
	cpSpaceAddBody(space, ballBody);
	
	//Create our shape associated with the ball's body
	     
	ballShape = cpCircleShapeNew(ballBody, 20.0, cpvzero);
	
	ballShape->e = 1.0; //Elasticty
	
	ballShape->u = 0.8; // Friction
	
	ballShape->data = ball; //Associate without ball's UIImageView
		
	// Add the shape to out space
			
	cpSpaceAddShape(space, ballShape);

Is it simply a case of me missing something?

Posted: **Fri Mar 26, 2010 6:03 am**

I have checked the code through and its the only time is called as well.

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cpSpaceRemoveBody(space, ballBody);
	 cpSpaceRemoveShape(space, ballShape);

Posted: **Fri Mar 26, 2010 8:12 am**

But are you sure that code isn't being called more than once? The reason I added those assertions is because I kept getting support questions from people trying to add or remove things more than once. I'm quite certain that the assertion is correct.

You should put a logging statement in there to check that you aren't actually trying to remove it twice.

Posted: **Fri Mar 26, 2010 3:39 pm**

Yep that was the problem. My code was repeating itself. A big thank-you for the help there

Posted: **Sat Mar 27, 2010 8:04 pm**

Sorry to post again

I've tried it with removing a static shape that has some Verts attached to it.

using this code :

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cpSpaceRemoveStaticShape(space, floorShape);
	cpSpaceRemoveBody(space, floorBody);

And this brings another assertion error. Now This is being used in exactly the same way as the previous example, so its not being called twice this time.

I'm guessing the issue is that you need to release the Verts first?

Anyway here's the code I'm using :

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	floorBody = cpBodyNew(INFINITY, INFINITY);
	
	floorBody->p = cpv(160, 480-350);	
	
	floorShape = cpPolyShapeNew(floorBody, 4, verts1, cpv(-320.0f / 2, 81.0f / 2));
	
	floorShape->e = 0.5; floorShape->u = 0.1; floorShape->collision_type = 0;
	
	floorShape->data = floor;
	
	cpSpaceAddStaticShape(space, floorShape);
	
	floorShape = cpPolyShapeNew(floorBody, 4, verts2, cpv(-320.0f / 2, 81.0f / 2));
	
	floorShape->e = 0.5; floorShape->u = 0.1; floorShape->collision_type = 0;
	
	floorShape->data = floor;
	
	cpSpaceAddStaticShape(space, floorShape);
	
	floorShape = cpPolyShapeNew(floorBody, 4, verts3, cpv(-320.0f / 2, 81.0f / 2));
	
	floorShape->e = 0.5; floorShape->u = 0.1; floorShape->collision_type = 0;
	
	floorShape->data = floor;
	
	cpSpaceAddStaticShape(space, floorShape);
	
	floorShape = cpPolyShapeNew(floorBody, 4, verts4, cpv(-320.0f / 2, 81.0f / 2));
	
	floorShape->e = 0.5; floorShape->u = 0.1; floorShape->collision_type = 0;
	
	floorShape->data = floor;
	
	cpSpaceAddStaticShape(space, floorShape);
	
	floorShape = cpPolyShapeNew(floorBody, 4, verts5, cpv(-320.0f / 2, 81.0f / 2));
	
	floorShape->e = 0.5; floorShape->u = 0.1; floorShape->collision_type = 0;
	
	floorShape->data = floor;
	
	cpSpaceAddStaticShape(space, floorShape);

With them declared in the header.

Any help would be fantastic!

(The error is :

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Initializing Chipmunk v5.1.0 (Debug Enabled)
Compile with NDEBUG defined to disable debug mode and assert() checks
Assertion failed: (cpArrayContains(space->bodies, body)), function cpSpaceRemoveBody, file /Users/rob/Documents/Iphone Development/Basic Assign Ap/balls Up 0.25/chipmunk/cpSpace.c, line 321.

Posted: **Sat Mar 27, 2010 8:39 pm**

No, you don't need to release the verts. The assertion is the check that the body exists in the space before you remove it. It doesn't exist therefore it was never added OR you re removing it twice.

Also, from the code you posted you can't remove all the shapes you added since you have overwritten your floorSpace. So how are you removing them?

Posted: **Sat Mar 27, 2010 10:27 pm**

Static bodies are never added to the space. Because they never move or change, you need the space to update them and don't want it to apply gravity to them. If you added the static body to the space in the first place your simulation wouldn't have worked.

Chipmunk Physics

Assertion failed error on remove of shape / body

Assertion failed error on remove of shape / body

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Re: Assertion failed error on remove of shape / body

Re: Assertion failed error on remove of shape / body

Re: Assertion failed error on remove of shape / body

Re: Assertion failed error on remove of shape / body

Re: Assertion failed error on remove of shape / body

Re: Assertion failed error on remove of shape / body

Re: Assertion failed error on remove of shape / body

Re: Assertion failed error on remove of shape / body