Program crashes when I use an EventReceiver

[nathanf534]

When I add an event receiver to my code, it crashes (its the MastEventReceiver class posted on our forums)

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int main(){
	cout<<"starting"<<endl;
	EventReceiver* er;
	cout<<er<<endl;
	IrrlichtDevice *device = createDevice(EDT_OPENGL, dimension2d<u32>(800,500), 32,false, false, true,er);//if I set the event receiver here, it crashes on this line

	//device->setEventReceiver(er);//if I set the event receiver here, it crashes at the indicated line below
	cout<<"end init"<<endl;
	NewtonWorld *nWorld = NewtonCreate();
	NewtonSetSolverModel(nWorld,0);
	device->setWindowCaption(L"Basic Collision Detection with Newton GD");
	IVideoDriver* driver = device->getVideoDriver();
	ISceneManager* smgr = device->getSceneManager();
	SObject sphere;
	SObject cube;
	NewtonCube* nCube;
	nCube->mesh = smgr->getMesh("C:/Models/testCube.b3d");//CRASHES HERE
	nCube->node = smgr->addMeshSceneNode(nCube->mesh);
	nCube->node->setPosition(vector3df(0,3,0));
	nCube->node->getMaterial(0).EmissiveColor.set(255,255,255,255);
	nCube->collision = NewtonCreateBox(nWorld, 2, 2, 2, NULL,NULL);
	nCube->gravity=-4;
	nCube->body = NewtonCreateBody(nWorld, nCube->collision);
	matrix4 mat;
	mat.setTranslation(vector3df(0,5,0));
	NewtonBodySetMatrix(nCube->body, &mat.M[0]);
	NewtonBodySetUserData(nCube->body,nCube);
	NewtonBodySetMassMatrix(nCube->body,10,150,150,150);
	NewtonBodySetTransformCallback(nCube->body,callbackTransform);
	NewtonBodySetForceAndTorqueCallback(nCube->body, ApplyForceAndTorqueEvent);

[Acki]

EventReceiver* er;

this creates an undefined pointer (to garbage) !!!

try this:

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EventReceiver er;
   IrrlichtDevice *device = createDevice(EDT_OPENGL, dimension2d<u32>(800,500), 32,false, false, true, &er);

but this won't work too, unless you create your own receiver class !!!
the tutorials are showing this pretty well !!!

[nathanf534]

I changed the code you said, but it still does the same thing. Also, what do you mean by it won't work unless I create my own receiver class? I'm using the MastEventReceiver (just renamed it to EventReceiver).

[Acki]

then tell us where it crashes, how it crashes and the error message you got...

[nathanf534]

I put where it crashes in the comments of the code. When it crashes, I just get the windows error message "IrrlichtGame.exe has stopped working", and it exits.

[Acki]

you're using this receiver: http://irrlicht.sourceforge.net/phpBB2/ ... hp?t=21657 ???
creating and passing it to the device like I described works like expected, but you'll have to update the onEvent function declaration, because it's out of date...
also if you don't change the onEvent declaration it should not compile !!!

[nathanf534]

yea, I updated the OnEvent method, and it compiles fine. It just crashes while it's running.

[Acki]

for me it runns like a charm !!!
I bet the error is somewhere else in your code..
also this tells me that it's not the receiver himselve:

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//device->setEventReceiver(er);//if I set the event receiver here, it crashes at the indicated line below 
...
nCube->mesh = smgr->getMesh("C:/Models/testCube.b3d");//CRASHES HERE 

[nathanf534]

hmm... I changed

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NewtonCube *nCube;

to

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NewtonCube nCube;

(and changed other parts of the code to make that work) and it seems to be working now. I guess that just didn't show up until I tried to add an eventReceiver... wierd

Thanks for helping me

[Acki]

aha, of course the same like with the receiver

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   NewtonCube* nCube;

this creates an undefined pointer (to garbage), too !!!
maybe take a deeper look on pointers...

[nathanf534]

I always thought

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Object name;

and

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Object* name;

were the exact same except that the 2nd returns a pointer to the object... but I guess I'm wrong. Ill go look that up.

[Zeus]

you realy should learn something about pointers and references ...

http://www.cplusplus.com/doc/tutorial/pointers/
http://www.augustcouncil.com/~tgibson/tutorial/ptr.html

your object reference has to exists if you want to use it by pointers cause the pointer himself is no valid object ...

regards zeus

[nathanf534]

Thanks, those explained a lot to me.

[polylux]

The base line is:

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Object *name;

creates a pointer that's literally pointing to nowhere and - more importantly for you - DOES NOT create an object along with it.
What you can do now is let it point to (assign) an existing object or you create an object of type "Object" explicitly with the "new" operator:

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name = new Object();

Don't forget that you'll have to destroy (delete) dynamically allocated objects when you don't need them anymore:

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delete name;

Hope this helps a bit.

Cheers,
p.