dynamic MeshBuffer, Mesh, and MeshSceneNode?

[phixuannhat]

I have this problem where I need to create/edit/delete Meshbuffers in a Mesh based on some dynamic data.

The problem is this, after I create the MeshSceneNodefrom the intial Mesh, I can only edit/delete existing MeshBuffers but not add new buffers from new data, otherwise it crashes when smgr->drawAll(). I've tried set the Mesh to EHM_DYNAMIC and used setDirty() after changing buffers, but no good.

Below are the simplified proj to reproduce this problem

Code: Select all

class TMesh
{
public:
	SMesh *Mesh;

	TMesh()
	{
		Mesh = new SMesh();
	}

	~TMesh()
	{
		Mesh->drop();
	}

	void init(array<SColor> &colors)
	{
		int i;
		for (i=0; i<colors.size(); i++)
			addstrip(colors[i], i);

		if(i < Mesh->getMeshBufferCount())
		{
			// clear the rest
			for (int j=i; j < Mesh->getMeshBufferCount(); j++)
				Mesh->getMeshBuffer(j)->drop();
			Mesh->MeshBuffers.erase(i, Mesh->getMeshBufferCount()-i);
		}
		Mesh->recalculateBoundingBox();
	}

	void addstrip(SColor color, u32 bufNum)
	{
		SMeshBuffer *buf = 0;
		if (bufNum < Mesh->getMeshBufferCount())
			buf = (SMeshBuffer*)Mesh->getMeshBuffer(bufNum);
		else
		{
			buf = new SMeshBuffer();
			Mesh->addMeshBuffer(buf);
		}
		buf->Vertices.set_used(3);

		buf->Vertices[0] = S3DVertex(vector3df(0, bufNum*100, 0), vector3df(0,1,0), color, vector2df(0,0));
		buf->Vertices[1] = S3DVertex(vector3df(0, bufNum*100, 100), vector3df(0,1,0), color, vector2df(0,0));
		buf->Vertices[2] = S3DVertex(vector3df(100, bufNum*100, 0), vector3df(0,1,0), color, vector2df(0,0));

		buf->Indices.set_used(3);
		buf->Indices[0] = 0;
		buf->Indices[1] = 1;
		buf->Indices[2] = 2;

		buf->recalculateBoundingBox();
	}

};

class MyEventReceiver : public IEventReceiver
{
public:
	// This is the one method that we have to implement
	virtual bool OnEvent(const SEvent& event)
	{
		// Remember whether each key is down or up
		if (event.EventType == irr::EET_KEY_INPUT_EVENT)
			KeyIsDown[event.KeyInput.Key] = event.KeyInput.PressedDown;

		return false;
	}

	// This is used to check whether a key is being held down
	virtual bool IsKeyDown(EKEY_CODE keyCode) const
	{
		return KeyIsDown[keyCode];
	}

	MyEventReceiver()
	{
		for (u32 i=0; i<KEY_KEY_CODES_COUNT; ++i)
			KeyIsDown[i] = false;
	}

private:
	// We use this array to store the current state of each key
	bool KeyIsDown[KEY_KEY_CODES_COUNT];
};

int main()
{
	MyEventReceiver rv;
	IrrlichtDevice *device = createDevice(EDT_OPENGL, dimension2du(800, 600), 32, false, false, false, &rv);
	if(!device)
		return 1;

	IVideoDriver *driver = device->getVideoDriver();
	ISceneManager *smgr = device->getSceneManager();
	device->setWindowCaption(L"Irrlicht Example for SMesh usage");

	TMesh mesh;
	array<SColor> colors;
	colors.push_back(SColor(255, rand()%256, rand()%256, rand()%256));
	colors.push_back(SColor(255, rand()%256, rand()%256, rand()%256));
	mesh.init(colors);

	// Add mesh to the scene graph
	IMeshSceneNode *meshnode = smgr->addMeshSceneNode(mesh.Mesh);
	meshnode->setMaterialFlag(EMF_LIGHTING, false);

	ICameraSceneNode* camera = smgr->addCameraSceneNodeFPS();
	camera->setPosition(vector3df(-20.f, 150.f, -20.f));
	camera->setTarget(vector3df(0,0,0));

	while(device->run())
	{

		if(rv.IsKeyDown(irr::KEY_KEY_1))
		{
			colors.push_back(SColor(255, rand()%256, rand()%256, rand()%256));
 			mesh.init(colors);
		}
		else if(rv.IsKeyDown(irr::KEY_KEY_2))
		{
			if (colors.size() != 0)
			{
				colors.erase(colors.size()-1);
				mesh.init(colors);
			}
		}

		driver->beginScene(true, true);
		smgr->drawAll();
		driver->endScene();
	}

	device->drop();

	return 0;
}

Anyone can help? Thanks

[phixuannhat]

any help?

[pippy3]

Do you know how to work your debugger? what is its output?

[phixuannhat]

This is what i get from debugger

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Unhandled exception at 0x100184ef in DynamicMesh.exe: 0xC0000005: Access violation reading location 0xbaadf00d.

and it breaks at line smgr->drawAll

So I think when I add new buffer to the mesh, somehow some pointers are lost therefore smgr can't access and draw

[REDDemon]

you have not dropped buf in "addStrip"

when you get it from mesh you have not to drop it.
But when you are creating a new buf with "new" you must drop it.

I let you the choice on how to handle that.

but this way i think is better:

Code: Select all

    buf = new SMeshBuffer(); 
    Mesh->addMeshBuffer(buf); 
    buf->drop();

i'm not sure this is the only problem with your code.