(C++) How to affect all scene nodes, including child nodes

[Panther]

This is a really small, simple snippet, but very useful. What it does is affect every object in your scene the same way. One classic example of needing to do this is with fog. First, you enable fog; then you have to turn it on for every object. Here's how to do that:

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	//Add some fog
	driver->setFog(video::SColor(0,200,200,200), true, 50, 3000, 0, true);

	//Go through all the scene nodes and make fog visible
	//(affects three levels of recursion, i.e. nodes, children, grandchildren)
	core::list<ISceneNode*>::Iterator it = smgr->getRootSceneNode()->getChildren().begin();
	for (; it != smgr->getRootSceneNode()->getChildren().end(); ++it)
	{
		(*it)->setMaterialFlag(video::EMF_FOG_ENABLE, true); //***
		core::list<ISceneNode*>::Iterator it2 = (*it)->getChildren().begin();
		for (; it2 != (*it)->getChildren().end(); ++it2)
		{
			(*it2)->setMaterialFlag(video::EMF_FOG_ENABLE, true);  //***
			core::list<ISceneNode*>::Iterator it3 = (*it2)->getChildren().begin();
			for (; it3 != (*it2)->getChildren().end(); ++it3)
			{
				(*it3)->setMaterialFlag(video::EMF_FOG_ENABLE, true); //***
			}
		}
	}

The above code can be easily modified to affect every object in a different way (other than fog). Just change the lines marked with ***.

[CuteAlien]

Why avoid real recursion?

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void RecursiveFunction(scene::ISceneNode* node_)
{
    if (!node_ )
        return;

    // Do something with the node here.

    // recursive call to children
    const core::list<scene::ISceneNode*> & children = node_->getChildren();
    core::list<scene::ISceneNode*>::Iterator it = children.begin();
    for (; it != children.end(); ++it)
    {
        RecursiveFunction(*it);
    }
}

To affect all nodes you can call the function now like:

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RecursiveFunction(smgr->getRootSceneNode());

[vitek]

Use real recursion, and make it generic...

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template< class Fun >
void applyToScene(Fun function, ISceneNode* node)
{
   function(node);

   core::list<ISceneNode*>::Iterator it = node->getChildren().begin(); 
   for (; it != node->getChildren().end(); ++it)
      applyToScene(function, *it);
}

To enable fog on the entire scene...

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struct setMaterialFlag
{
   setMaterialFlag(video::E_MATERIAL_FLAG flag, bool value)
      : Flag(flag)
      , Value(value)
   {
   }

   void operator()(ISceneNode* node)
   {
      node->setMaterialFlag(Flag, Value);
   }

   video::E_MATERIAL_FLAG Flag;
   bool Value;
};

// this does everything
applyToScene(setMaterialFlag(video::EMF_FOG_ENABLE, true), smgr->getRootSceneNode());

To set debug data visible...

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struct setDebugDataVisible
{
   setDebugDataVisible(bool visible)
      : Visible(visible)
   {
   }

   void operator()(ISceneNode* node)
   {
      node->setDebugDataVisible(Visible);
   }

   bool Visible;
};

// this does everything
applyToScene(setDebugDataVisible(true), smgr->getRootSceneNode());