RegionWalkers.h

#ifndef REGIONWALKERS_H_
#define REGIONWALKERS_H_


namespace map {

/** greebo: Sets the "excluded" bit in the Node according to the given boolean.
 *
 * @exclude: set to TRUE if you want to exclude the node.
 */
inline void excludeNode(scene::INodePtr node, bool exclude) 
{
    if (!node->supportsStateFlag(scene::Node::eExcluded))
    {
        return;
    }

	if (exclude) 
    {
		node->enable(scene::Node::eExcluded);
	}
	else {
		node->disable(scene::Node::eExcluded);
	}
}

/** greebo: Sets/resets the exclude bit on the visited node
 */
class ExcludeAllWalker :
	public scene::NodeVisitor
{
	bool _exclude;
public:
	ExcludeAllWalker(bool exclude) :
		_exclude(exclude)
	{}

	bool pre(const scene::INodePtr& node)
	{
		excludeNode(node, _exclude);

		return true;
	}
};

/** greebo: Sets the exclusion status of all the objects WITHIN the bounds.
 *
 * All the objects outside the bounds get their status set to the opposite.
 */
class ExcludeRegionedWalker :
	public scene::NodeVisitor
{
	bool _exclude;
	// The reference to the currently active region bounds
	AABB& _regionAABB;

public:
	ExcludeRegionedWalker(bool exclude, AABB& regionAABB) :
		_exclude(exclude),
		_regionAABB(regionAABB)
	{}

	bool pre(const scene::INodePtr& node)
	{
		// Check whether the instance is within the region
		bool contained = node->worldAABB().intersects(_regionAABB);

		if (contained) {
			// The contained stuff is set according to the _exclude parameter
			excludeNode(node, _exclude);
		}
		else {
			// This is an object outside the bounds, set it to !_exclude
			// as the _exclude should apply to the objects within.
			excludeNode(node, !_exclude);
		}

		// Traverse the children as well
		return true;
	}
};

/** greebo: This class is used indirectly by the map saving walker to save the region.
 *
 * The map saving walker calls a function RegionManager::traverseRegion() which
 * traverses the given node with this walker.
 *
 * This ExcludeNonRegionedWalker again invokes the map saving walker, if the
 * visited items are regioned only, of course.
 */
class ExcludeNonRegionedWalker :
	public scene::NodeVisitor
{
	scene::NodeVisitor& _walker;
	mutable bool _skip;

public:
	ExcludeNonRegionedWalker(scene::NodeVisitor& walker) :
		_walker(walker),
		_skip(false)
	{}

	virtual bool pre(const scene::INodePtr& node) {
		// Don't save excluded nodes or the Scenegraph root
		if (node->excluded() || node->isRoot()) {
			_skip = true;
			return false;
		}
		else {
			// Item passed the check, call the given walker's pre() method.
			_walker.pre(node);
		}
		return true;
	}

	virtual void post(const scene::INodePtr& node) {
		if (_skip) {
			// The node failed to pass the check in pre()
			_skip = false;
		}
		else {
			// The node passed the check in pre(), we have to call post() as well.
			_walker.post(node);
		}
	}
};

} // namespace map

#endif /*REGIONWALKERS_H_*/