Expose getPointedThing to Lua

This commit introduces Raycast, a Lua user object, which can be
used to perform a raycast on the map. The ray is continuable, so one can
also get hidden nodes (for example to see trough glass).

doc/lua_api.txt

@@ -2557,6 +2557,12 @@ and `minetest.auth_reload` call the authetification handler.
     * `pos2`: Second position
     * `stepsize`: smaller gives more accurate results but requires more computing
       time. Default is `1`.
+* `minetest.raycast(pos1, pos2, objects, liquids)`: returns `Raycast`
+    * Creates a `Raycast` object.
+    * `pos1`: start of the ray
+    * `pos2`: end of the ray
+    * `objects` : if false, only nodes will be returned. Default is `true`.
+    * `liquids' : if false, liquid nodes won't be returned. Default is `false`.
 * `minetest.find_path(pos1,pos2,searchdistance,max_jump,max_drop,algorithm)`
     * returns table containing path
     * returns a table of 3D points representing a path from `pos1` to `pos2` or `nil`
@@ -3755,6 +3761,26 @@ It can be created via `Settings(filename)`.
     * Writes changes to file.
 * `to_table()`: returns `{[key1]=value1,...}`
 
+### `Raycast`
+A raycast on the map. It works with selection boxes.
+Can be used as an iterator in a for loop.
+
+The map is loaded as the ray advances. If the
+map is modified after the `Raycast` is created,
+the changes may or may not have an effect on
+the object.
+
+It can be created via `Raycast(pos1, pos2, objects, liquids)` or
+`minetest.raycast(pos1, pos2, objects, liquids)` where:
+    * `pos1`: start of the ray
+    * `pos2`: end of the ray
+    * `objects` : if false, only nodes will be returned. Default is true.
+    * `liquids' : if false, liquid nodes won't be returned. Default is false.
+
+#### Methods
+* `next()`: returns a `pointed_thing`
+    * Returns the next thing pointed by the ray or nil.
+
 Mapgen objects
 --------------
 A mapgen object is a construct used in map generation. Mapgen objects can be used

src/CMakeLists.txt

@@ -428,9 +428,9 @@ set(common_SRCS
 	porting.cpp
 	profiler.cpp
 	quicktune.cpp
+	raycast.cpp
 	reflowscan.cpp
 	remoteplayer.cpp
-	raycast.cpp
 	rollback.cpp
 	rollback_interface.cpp
 	serialization.cpp

src/activeobject.h

@@ -65,7 +65,7 @@ public:
 	{
 	}
 
-	u16 getId()
+	u16 getId() const
 	{
 		return m_id;
 	}
@@ -76,7 +76,28 @@ public:
 	}
 
 	virtual ActiveObjectType getType() const = 0;
+
+
+	/*!
+	 * Returns the collision box of the object.
+	 * This box is translated by the object's
+	 * location.
+	 * The box's coordinates are world coordinates.
+	 * @returns true if the object has a collision box.
+	 */
 	virtual bool getCollisionBox(aabb3f *toset) const = 0;
+
+
+	/*!
+	 * Returns the selection box of the object.
+	 * This box is not translated when the
+	 * object moves.
+	 * The box's coordinates are world coordinates.
+	 * @returns true if the object has a selection box.
+	 */
+	virtual bool getSelectionBox(aabb3f *toset) const = 0;
+
+
 	virtual bool collideWithObjects() const = 0;
 protected:
 	u16 m_id; // 0 is invalid, "no id"

src/clientenvironment.cpp

@@ -604,240 +604,31 @@ ClientEnvEvent ClientEnvironment::getClientEnvEvent()
 	return event;
 }
 
-ClientActiveObject * ClientEnvironment::getSelectedActiveObject(
+void ClientEnvironment::getSelectedActiveObjects(
-	const core::line3d<f32> &shootline_on_map, v3f *intersection_point,
+	const core::line3d<f32> &shootline_on_map,
-	v3s16 *intersection_normal)
+	std::vector<PointedThing> &objects)
 {
-	std::vector<DistanceSortedActiveObject> objects;
+	std::vector<DistanceSortedActiveObject> allObjects;
 	getActiveObjects(shootline_on_map.start,
-		shootline_on_map.getLength() + 3, objects);
+		shootline_on_map.getLength() + 10.0f, allObjects);
 	const v3f line_vector = shootline_on_map.getVector();
 
-	// Sort them.
+	for (u32 i = 0; i < allObjects.size(); i++) {
-	// After this, the closest object is the first in the array.
+		ClientActiveObject *obj = allObjects[i].obj;
-	std::sort(objects.begin(), objects.end());
+		aabb3f selection_box;
-
+		if (!obj->getSelectionBox(&selection_box))
-	/* Because objects can have different nodebox sizes,
-	 * the object whose center is the nearest isn't necessarily
-	 * the closest one. If an object is found, don't stop
-	 * immediately. */
-
-	f32 d_min = shootline_on_map.getLength();
-	ClientActiveObject *nearest_obj = NULL;
-	for (u32 i = 0; i < objects.size(); i++) {
-		ClientActiveObject *obj = objects[i].obj;
-
-		aabb3f *selection_box = obj->getSelectionBox();
-		if (selection_box == NULL)
 			continue;
-
 		v3f pos = obj->getPosition();
-
+		aabb3f offsetted_box(selection_box.MinEdge + pos,
-		aabb3f offsetted_box(selection_box->MinEdge + pos,
+			selection_box.MaxEdge + pos);
-			selection_box->MaxEdge + pos);
-
-		if (offsetted_box.getCenter().getDistanceFrom(
-			shootline_on_map.start) > d_min + 9.6f*BS) {
-			// Probably there is no active object that has bigger nodebox than
-			// (-5.5,-5.5,-5.5,5.5,5.5,5.5)
-			// 9.6 > 5.5*sqrt(3)
-			break;
-		}
 
 		v3f current_intersection;
 		v3s16 current_normal;
 		if (boxLineCollision(offsetted_box, shootline_on_map.start, line_vector,
 				&current_intersection, &current_normal)) {
-			f32 d_current = current_intersection.getDistanceFrom(
+			objects.push_back(PointedThing(
-				shootline_on_map.start);
+				(s16) obj->getId(), current_intersection, current_normal,
-			if (d_current <= d_min) {
+				(current_intersection - shootline_on_map.start).getLengthSQ()));
-				d_min = d_current;
-				nearest_obj = obj;
-				*intersection_point = current_intersection;
-				*intersection_normal = current_normal;
 		}
 	}
 }
-
-	return nearest_obj;
-}
-
-/*
-	Check if a node is pointable
-*/
-static inline bool isPointableNode(const MapNode &n,
-	INodeDefManager *ndef, bool liquids_pointable)
-{
-	const ContentFeatures &features = ndef->get(n);
-	return features.pointable ||
-		(liquids_pointable && features.isLiquid());
-}
-
-PointedThing ClientEnvironment::getPointedThing(
-	core::line3d<f32> shootline,
-	bool liquids_pointable,
-	bool look_for_object)
-{
-	PointedThing result;
-
-	INodeDefManager *nodedef = m_map->getNodeDefManager();
-
-	core::aabbox3d<s16> maximal_exceed = nodedef->getSelectionBoxIntUnion();
-	// The code needs to search these nodes
-	core::aabbox3d<s16> search_range(-maximal_exceed.MaxEdge,
-		-maximal_exceed.MinEdge);
-	// If a node is found, there might be a larger node behind.
-	// To find it, we have to go further.
-	s16 maximal_overcheck =
-		std::max(abs(search_range.MinEdge.X), abs(search_range.MaxEdge.X))
-			+ std::max(abs(search_range.MinEdge.Y), abs(search_range.MaxEdge.Y))
-			+ std::max(abs(search_range.MinEdge.Z), abs(search_range.MaxEdge.Z));
-
-	const v3f original_vector = shootline.getVector();
-	const f32 original_length = original_vector.getLength();
-
-	f32 min_distance = original_length;
-
-	// First try to find an active object
-	if (look_for_object) {
-		ClientActiveObject *selected_object = getSelectedActiveObject(
-			shootline, &result.intersection_point,
-			&result.intersection_normal);
-
-		if (selected_object != NULL) {
-			min_distance =
-				(result.intersection_point - shootline.start).getLength();
-
-			result.type = POINTEDTHING_OBJECT;
-			result.object_id = selected_object->getId();
-		}
-	}
-
-	// Reduce shootline
-	if (original_length > 0) {
-		shootline.end = shootline.start
-			+ shootline.getVector() / original_length * min_distance;
-	}
-
-	// Try to find a node that is closer than the selected active
-	// object (if it exists).
-
-	voxalgo::VoxelLineIterator iterator(shootline.start / BS,
-		shootline.getVector() / BS);
-	v3s16 oldnode = iterator.m_current_node_pos;
-	// Indicates that a node was found.
-	bool is_node_found = false;
-	// If a node is found, it is possible that there's a node
-	// behind it with a large nodebox, so continue the search.
-	u16 node_foundcounter = 0;
-	// If a node is found, this is the center of the
-	// first nodebox the shootline meets.
-	v3f found_boxcenter(0, 0, 0);
-	// The untested nodes are in this range.
-	core::aabbox3d<s16> new_nodes;
-	while (true) {
-		// Test the nodes around the current node in search_range.
-		new_nodes = search_range;
-		new_nodes.MinEdge += iterator.m_current_node_pos;
-		new_nodes.MaxEdge += iterator.m_current_node_pos;
-
-		// Only check new nodes
-		v3s16 delta = iterator.m_current_node_pos - oldnode;
-		if (delta.X > 0)
-			new_nodes.MinEdge.X = new_nodes.MaxEdge.X;
-		else if (delta.X < 0)
-			new_nodes.MaxEdge.X = new_nodes.MinEdge.X;
-		else if (delta.Y > 0)
-			new_nodes.MinEdge.Y = new_nodes.MaxEdge.Y;
-		else if (delta.Y < 0)
-			new_nodes.MaxEdge.Y = new_nodes.MinEdge.Y;
-		else if (delta.Z > 0)
-			new_nodes.MinEdge.Z = new_nodes.MaxEdge.Z;
-		else if (delta.Z < 0)
-			new_nodes.MaxEdge.Z = new_nodes.MinEdge.Z;
-
-		// For each untested node
-		for (s16 x = new_nodes.MinEdge.X; x <= new_nodes.MaxEdge.X; x++) {
-			for (s16 y = new_nodes.MinEdge.Y; y <= new_nodes.MaxEdge.Y; y++) {
-				for (s16 z = new_nodes.MinEdge.Z; z <= new_nodes.MaxEdge.Z; z++) {
-					MapNode n;
-					v3s16 np(x, y, z);
-					bool is_valid_position;
-
-					n = m_map->getNodeNoEx(np, &is_valid_position);
-					if (!(is_valid_position &&
-						isPointableNode(n, nodedef, liquids_pointable))) {
-						continue;
-					}
-					std::vector<aabb3f> boxes;
-					n.getSelectionBoxes(nodedef, &boxes,
-						n.getNeighbors(np, m_map));
-
-					v3f npf = intToFloat(np, BS);
-					for (std::vector<aabb3f>::const_iterator i = boxes.begin();
-						i != boxes.end(); ++i) {
-						aabb3f box = *i;
-						box.MinEdge += npf;
-						box.MaxEdge += npf;
-						v3f intersection_point;
-						v3s16 intersection_normal;
-						if (!boxLineCollision(box, shootline.start, shootline.getVector(),
-							&intersection_point, &intersection_normal)) {
-							continue;
-						}
-						f32 distance = (intersection_point - shootline.start).getLength();
-						if (distance >= min_distance) {
-							continue;
-						}
-						result.type = POINTEDTHING_NODE;
-						result.node_undersurface = np;
-						result.intersection_point = intersection_point;
-						result.intersection_normal = intersection_normal;
-						found_boxcenter = box.getCenter();
-						min_distance = distance;
-						is_node_found = true;
-					}
-				}
-			}
-		}
-		if (is_node_found) {
-			node_foundcounter++;
-			if (node_foundcounter > maximal_overcheck) {
-				break;
-			}
-		}
-		// Next node
-		if (iterator.hasNext()) {
-			oldnode = iterator.m_current_node_pos;
-			iterator.next();
-		} else {
-			break;
-		}
-	}
-
-	if (is_node_found) {
-		// Set undersurface and abovesurface nodes
-		f32 d = 0.002 * BS;
-		v3f fake_intersection = result.intersection_point;
-		// Move intersection towards its source block.
-		if (fake_intersection.X < found_boxcenter.X)
-			fake_intersection.X += d;
-		else
-			fake_intersection.X -= d;
-
-		if (fake_intersection.Y < found_boxcenter.Y)
-			fake_intersection.Y += d;
-		else
-			fake_intersection.Y -= d;
-
-		if (fake_intersection.Z < found_boxcenter.Z)
-			fake_intersection.Z += d;
-		else
-			fake_intersection.Z -= d;
-
-		result.node_real_undersurface = floatToInt(fake_intersection, BS);
-		result.node_abovesurface = result.node_real_undersurface
-			+ result.intersection_normal;
-	}
-	return result;
-}

src/clientenvironment.h

@@ -30,7 +30,6 @@ class ClientScripting;
 class ClientActiveObject;
 class GenericCAO;
 class LocalPlayer;
-struct PointedThing;
 
 /*
 	The client-side environment.
@@ -125,44 +124,15 @@ public:
 		std::vector<DistanceSortedActiveObject> &dest);
 
 	bool hasClientEnvEvents() const { return !m_client_event_queue.empty(); }
+
 	// Get event from queue. If queue is empty, it triggers an assertion failure.
 	ClientEnvEvent getClientEnvEvent();
 
-	/*!
+	virtual void getSelectedActiveObjects(
-	 * Gets closest object pointed by the shootline.
-	 * Returns NULL if not found.
-	 *
-	 * \param[in]  shootline_on_map    the shootline for
-	 * the test in world coordinates
-	 * \param[out] intersection_point  the first point where
-	 * the shootline meets the object. Valid only if
-	 * not NULL is returned.
-	 * \param[out] intersection_normal the normal vector of
-	 * the intersection, pointing outwards. Zero vector if
-	 * the shootline starts in an active object.
-	 * Valid only if not NULL is returned.
-	 */
-	ClientActiveObject * getSelectedActiveObject(
 		const core::line3d<f32> &shootline_on_map,
-		v3f *intersection_point,
+		std::vector<PointedThing> &objects
-		v3s16 *intersection_normal
 	);
 
-	/*!
-	 * Performs a raycast on the world.
-	 * Returns the first thing the shootline meets.
-	 *
-	 * @param[in]  shootline         the shootline, starting from
-	 * the camera position. This also gives the maximal distance
-	 * of the search.
-	 * @param[in]  liquids_pointable if false, liquids are ignored
-	 * @param[in]  look_for_object   if false, objects are ignored
-	 */
-	PointedThing getPointedThing(
-		core::line3d<f32> shootline,
-		bool liquids_pointable,
-		bool look_for_object);
-
 	u16 attachement_parent_ids[USHRT_MAX + 1];
 
 	const std::list<std::string> &getPlayerNames() { return m_player_names; }

src/clientobject.h

@@ -44,8 +44,8 @@ public:
 	virtual void updateLight(u8 light_at_pos){}
 	virtual void updateLightNoCheck(u8 light_at_pos){}
 	virtual v3s16 getLightPosition(){return v3s16(0,0,0);}
-	virtual aabb3f *getSelectionBox() { return NULL; }
 	virtual bool getCollisionBox(aabb3f *toset) const { return false; }
+	virtual bool getSelectionBox(aabb3f *toset) const { return false; }
 	virtual bool collideWithObjects() const { return false; }
 	virtual v3f getPosition(){ return v3f(0,0,0); }
 	virtual float getYaw() const { return 0; }

src/content_cao.cpp

@@ -283,8 +283,14 @@ public:
 
 	void initialize(const std::string &data);
 
-	aabb3f *getSelectionBox()
+
-		{return &m_selection_box;}
+	virtual bool getSelectionBox(aabb3f *toset) const
+	{
+		*toset = m_selection_box;
+		return true;
+	}
+
+
 	v3f getPosition()
 		{return m_position;}
 	inline float getYaw() const
@@ -605,11 +611,14 @@ GenericCAO::~GenericCAO()
 	removeFromScene(true);
 }
 
-aabb3f *GenericCAO::getSelectionBox()
+bool GenericCAO::getSelectionBox(aabb3f *toset) const
 {
-	if(!m_prop.is_visible || !m_is_visible || m_is_local_player || getParent() != NULL)
+	if (!m_prop.is_visible || !m_is_visible || m_is_local_player
-		return NULL;
+			|| getParent() != NULL){
-	return &m_selection_box;
+		return false;
+	}
+	*toset = m_selection_box;
+	return true;
 }
 
 v3f GenericCAO::getPosition()
@@ -658,7 +667,7 @@ void GenericCAO::setAttachments()
 	updateAttachments();
 }
 
-ClientActiveObject* GenericCAO::getParent()
+ClientActiveObject* GenericCAO::getParent() const
 {
 	ClientActiveObject *obj = NULL;
 

src/content_cao.h

@@ -129,13 +129,13 @@ public:
 
 	void processInitData(const std::string &data);
 
-	ClientActiveObject *getParent();
+	ClientActiveObject *getParent() const;
 
 	bool getCollisionBox(aabb3f *toset) const;
 
 	bool collideWithObjects() const;
 
-	aabb3f *getSelectionBox();
+	virtual bool getSelectionBox(aabb3f *toset) const;
 
 	v3f getPosition();
 	inline float getYaw() const

src/content_sao.cpp

@@ -91,6 +91,9 @@ public:
 	}
 
 	bool getCollisionBox(aabb3f *toset) const { return false; }
+
+	virtual bool getSelectionBox(aabb3f *toset) const { return false; }
+
 	bool collideWithObjects() const { return false; }
 
 private:
@@ -746,6 +749,18 @@ bool LuaEntitySAO::getCollisionBox(aabb3f *toset) const
 	return false;
 }
 
+bool LuaEntitySAO::getSelectionBox(aabb3f *toset) const
+{
+	if (!m_prop.is_visible) {
+		return false;
+	}
+
+	toset->MinEdge = m_prop.collisionbox.MinEdge * BS;
+	toset->MaxEdge = m_prop.collisionbox.MaxEdge * BS;
+
+	return true;
+}
+
 bool LuaEntitySAO::collideWithObjects() const
 {
 	return m_prop.collideWithObjects;
@@ -1405,3 +1420,14 @@ bool PlayerSAO::getCollisionBox(aabb3f *toset) const
 	toset->MaxEdge += m_base_position;
 	return true;
 }
+
+bool PlayerSAO::getSelectionBox(aabb3f *toset) const
+{
+	if (!m_prop.is_visible) {
+		return false;
+	}
+
+	getCollisionBox(toset);
+
+	return true;
+}

src/content_sao.h

@@ -127,6 +127,7 @@ public:
 			bool select_horiz_by_yawpitch);
 	std::string getName();
 	bool getCollisionBox(aabb3f *toset) const;
+	bool getSelectionBox(aabb3f *toset) const;
 	bool collideWithObjects() const;
 private:
 	std::string getPropertyPacket();
@@ -357,6 +358,7 @@ public:
 	}
 
 	bool getCollisionBox(aabb3f *toset) const;
+	bool getSelectionBox(aabb3f *toset) const;
 	bool collideWithObjects() const { return true; }
 
 	void finalize(RemotePlayer *player, const std::set<std::string> &privs);

src/environment.cpp

@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <fstream>
 #include "environment.h"
 #include "collision.h"
+#include "raycast.h"
 #include "serverobject.h"
 #include "scripting_server.h"
 #include "server.h"
@@ -83,6 +84,179 @@ float Environment::getTimeOfDayF()
 	return m_time_of_day_f;
 }
 
+/*
+	Check if a node is pointable
+*/
+inline static bool isPointableNode(const MapNode &n,
+			    INodeDefManager *nodedef , bool liquids_pointable)
+{
+	const ContentFeatures &features = nodedef->get(n);
+	return features.pointable ||
+	       (liquids_pointable && features.isLiquid());
+}
+
+void Environment::continueRaycast(RaycastState *state, PointedThing *result)
+{
+	INodeDefManager *nodedef = getMap().getNodeDefManager();
+	if (state->m_initialization_needed) {
+		// Add objects
+		if (state->m_objects_pointable) {
+			std::vector<PointedThing> found;
+			getSelectedActiveObjects(state->m_shootline, found);
+			for (std::vector<PointedThing>::iterator pointed = found.begin();
+					pointed != found.end(); ++pointed) {
+				state->m_found.push(*pointed);
+			}
+		}
+		// Set search range
+		core::aabbox3d<s16> maximal_exceed = nodedef->getSelectionBoxIntUnion();
+		state->m_search_range.MinEdge = -maximal_exceed.MaxEdge;
+		state->m_search_range.MaxEdge = -maximal_exceed.MinEdge;
+		// Setting is done
+		state->m_initialization_needed = false;
+	}
+
+	// The index of the first pointed thing that was not returned
+	// before. The last index which needs to be tested.
+	s16 lastIndex = state->m_iterator.m_last_index;
+	if (!state->m_found.empty()) {
+		lastIndex = state->m_iterator.getIndex(
+			floatToInt(state->m_found.top().intersection_point, BS));
+	}
+
+	Map &map = getMap();
+	// If a node is found, this is the center of the
+	// first nodebox the shootline meets.
+	v3f found_boxcenter(0, 0, 0);
+	// The untested nodes are in this range.
+	core::aabbox3d<s16> new_nodes;
+	while (state->m_iterator.m_current_index <= lastIndex) {
+		// Test the nodes around the current node in search_range.
+		new_nodes = state->m_search_range;
+		new_nodes.MinEdge += state->m_iterator.m_current_node_pos;
+		new_nodes.MaxEdge += state->m_iterator.m_current_node_pos;
+
+		// Only check new nodes
+		v3s16 delta = state->m_iterator.m_current_node_pos
+			- state->m_previous_node;
+		if (delta.X > 0) {
+			new_nodes.MinEdge.X = new_nodes.MaxEdge.X;
+		} else if (delta.X < 0) {
+			new_nodes.MaxEdge.X = new_nodes.MinEdge.X;
+		} else if (delta.Y > 0) {
+			new_nodes.MinEdge.Y = new_nodes.MaxEdge.Y;
+		} else if (delta.Y < 0) {
+			new_nodes.MaxEdge.Y = new_nodes.MinEdge.Y;
+		} else if (delta.Z > 0) {
+			new_nodes.MinEdge.Z = new_nodes.MaxEdge.Z;
+		} else if (delta.Z < 0) {
+			new_nodes.MaxEdge.Z = new_nodes.MinEdge.Z;
+		}
+
+		// For each untested node
+		for (s16 x = new_nodes.MinEdge.X; x <= new_nodes.MaxEdge.X; x++)
+		for (s16 y = new_nodes.MinEdge.Y; y <= new_nodes.MaxEdge.Y; y++)
+		for (s16 z = new_nodes.MinEdge.Z; z <= new_nodes.MaxEdge.Z; z++) {
+			MapNode n;
+			v3s16 np(x, y, z);
+			bool is_valid_position;
+
+			n = map.getNodeNoEx(np, &is_valid_position);
+			if (!(is_valid_position && isPointableNode(n, nodedef,
+					state->m_liquids_pointable))) {
+				continue;
+			}
+
+			PointedThing result;
+
+			std::vector<aabb3f> boxes;
+			n.getSelectionBoxes(nodedef, &boxes,
+				n.getNeighbors(np, &map));
+
+			// Is there a collision with a selection box?
+			bool is_colliding = false;
+			// Minimal distance of all collisions
+			float min_distance_sq = 10000000;
+
+			v3f npf = intToFloat(np, BS);
+			for (std::vector<aabb3f>::const_iterator i = boxes.begin();
+					i != boxes.end(); ++i) {
+				// Get current collision box
+				aabb3f box = *i;
+				box.MinEdge += npf;
+				box.MaxEdge += npf;
+
+				v3f intersection_point;
+				v3s16 intersection_normal;
+				if (!boxLineCollision(box, state->m_shootline.start,
+						state->m_shootline.getVector(), &intersection_point,
+						&intersection_normal))
+					continue;
+
+				f32 distanceSq = (intersection_point
+					- state->m_shootline.start).getLengthSQ();
+				// If this is the nearest collision, save it
+				if (min_distance_sq > distanceSq) {
+					min_distance_sq = distanceSq;
+					result.intersection_point = intersection_point;
+					result.intersection_normal = intersection_normal;
+					found_boxcenter = box.getCenter();
+					is_colliding = true;
+				}
+			}
+			// If there wasn't a collision, stop
+			if (!is_colliding) {
+				continue;
+			}
+			result.type = POINTEDTHING_NODE;
+			result.node_undersurface = np;
+			result.distanceSq = min_distance_sq;
+			// Set undersurface and abovesurface nodes
+			f32 d = 0.002 * BS;
+			v3f fake_intersection = result.intersection_point;
+			// Move intersection towards its source block.
+			if (fake_intersection.X < found_boxcenter.X) {
+				fake_intersection.X += d;
+			} else {
+				fake_intersection.X -= d;
+			}
+			if (fake_intersection.Y < found_boxcenter.Y) {
+				fake_intersection.Y += d;
+			} else {
+				fake_intersection.Y -= d;
+			}
+			if (fake_intersection.Z < found_boxcenter.Z) {
+				fake_intersection.Z += d;
+			} else {
+				fake_intersection.Z -= d;
+			}
+			result.node_real_undersurface = floatToInt(
+				fake_intersection, BS);
+			result.node_abovesurface = result.node_real_undersurface
+				+ result.intersection_normal;
+			// Push found PointedThing
+			state->m_found.push(result);
+			// If this is nearer than the old nearest object,
+			// the search can be shorter
+			s16 newIndex = state->m_iterator.getIndex(
+				result.node_real_undersurface);
+			if (newIndex < lastIndex) {
+				lastIndex = newIndex;
+			}
+		}
+		// Next node
+		state->m_previous_node = state->m_iterator.m_current_node_pos;
+		state->m_iterator.next();
+	}
+	// Return empty PointedThing if nothing left on the ray
+	if (state->m_found.empty()) {
+		result->type = POINTEDTHING_NOTHING;
+	} else {
+		*result = state->m_found.top();
+		state->m_found.pop();
+	}
+}
+
 void Environment::stepTimeOfDay(float dtime)
 {
 	MutexAutoLock lock(this->m_time_lock);

src/environment.h

@@ -42,6 +42,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 class IGameDef;
 class Map;
+struct PointedThing;
+class RaycastState;
 
 class Environment
 {
@@ -76,6 +78,26 @@ public:
 
 	u32 getDayCount();
 
+	/*!
+	 * Gets the objects pointed by the shootline as
+	 * pointed things.
+	 * If this is a client environment, the local player
+	 * won't be returned.
+	 * @param[in]  shootline_on_map the shootline for
+	 * the test in world coordinates
+	 *
+	 * @param[out] objects          found objects
+	 */
+	virtual void getSelectedActiveObjects(const core::line3d<f32> &shootline_on_map,
+			std::vector<PointedThing> &objects) = 0;
+
+	/*!
+	 * Returns the next node or object the shootline meets.
+	 * @param state current state of the raycast
+	 * @result output, will contain the next pointed thing
+	 */
+	void continueRaycast(RaycastState *state, PointedThing *result);
+
 	// counter used internally when triggering ABMs
 	u32 m_added_objects;
 

src/game.cpp

@@ -50,6 +50,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "particles.h"
 #include "profiler.h"
 #include "quicktune_shortcutter.h"
+#include "raycast.h"
 #include "server.h"
 #include "settings.h"
 #include "sky.h"
@@ -3667,28 +3668,22 @@ PointedThing Game::updatePointedThing(
 	static thread_local const bool show_entity_selectionbox = g_settings->getBool(
 		"show_entity_selectionbox");
 
-	ClientMap &map = client->getEnv().getClientMap();
+	ClientEnvironment &env = client->getEnv();
-	INodeDefManager *nodedef=client->getNodeDefManager();
+	ClientMap &map = env.getClientMap();
+	INodeDefManager *nodedef = map.getNodeDefManager();
 
 	runData.selected_object = NULL;
 
-	PointedThing result=client->getEnv().getPointedThing(
+	RaycastState s(shootline, look_for_object, liquids_pointable);
-		shootline, liquids_pointable, look_for_object);
+	PointedThing result;
+	env.continueRaycast(&s, &result);
 	if (result.type == POINTEDTHING_OBJECT) {
 		runData.selected_object = client->getEnv().getActiveObject(result.object_id);
-		if (show_entity_selectionbox && runData.selected_object->doShowSelectionBox()) {
+		aabb3f selection_box;
-			aabb3f *selection_box = runData.selected_object->getSelectionBox();
+		if (show_entity_selectionbox && runData.selected_object->doShowSelectionBox() &&
-
+				runData.selected_object->getSelectionBox(&selection_box)) {
-			// Box should exist because object was
-			// returned in the first place
-
-			assert(selection_box);
-
 			v3f pos = runData.selected_object->getPosition();
-			selectionboxes->push_back(aabb3f(
+			selectionboxes->push_back(aabb3f(selection_box));
-				selection_box->MinEdge, selection_box->MaxEdge));
-			selectionboxes->push_back(
-				aabb3f(selection_box->MinEdge, selection_box->MaxEdge));
 			hud->setSelectionPos(pos, camera_offset);
 		}
 	} else if (result.type == POINTEDTHING_NODE) {

src/raycast.cpp

@@ -17,11 +17,47 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
+#include "raycast.h"
 #include "irr_v3d.h"
 #include "irr_aabb3d.h"
+#include "constants.h"
+
+bool RaycastSort::operator() (const PointedThing &pt1,
+	const PointedThing &pt2) const
+{
+	// "nothing" can not be sorted
+	assert(pt1.type != POINTEDTHING_NOTHING);
+	assert(pt2.type != POINTEDTHING_NOTHING);
+	// returns false if pt1 is nearer than pt2
+	if (pt1.distanceSq < pt2.distanceSq) {
+		return false;
+	} else if (pt1.distanceSq == pt2.distanceSq) {
+		// Sort them to allow only one order
+		if (pt1.type == POINTEDTHING_OBJECT)
+			return (pt2.type == POINTEDTHING_OBJECT
+				&& pt1.object_id < pt2.object_id);
+		else
+			return (pt2.type == POINTEDTHING_OBJECT
+				|| pt1.node_undersurface < pt2.node_undersurface);
+	}
+	return true;
+}
+
+
+RaycastState::RaycastState(const core::line3d<f32> &shootline,
+	bool objects_pointable, bool liquids_pointable) :
+	m_shootline(shootline),
+	m_iterator(shootline.start / BS, shootline.getVector() / BS),
+	m_previous_node(m_iterator.m_current_node_pos),
+	m_objects_pointable(objects_pointable),
+	m_liquids_pointable(liquids_pointable)
+{
+}
+
 
 bool boxLineCollision(const aabb3f &box, const v3f &start,
-		const v3f &dir, v3f *collision_point, v3s16 *collision_normal) {
+	const v3f &dir, v3f *collision_point, v3s16 *collision_normal)
+{
 	if (box.isPointInside(start)) {
 		*collision_point = start;
 		collision_normal->set(0, 0, 0);

src/raycast.h

@@ -20,6 +20,49 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #ifndef SRC_RAYCAST_H_
 #define SRC_RAYCAST_H_
 
+#include "voxelalgorithms.h"
+#include "util/pointedthing.h"
+
+//! Sorts PointedThings based on their distance.
+struct RaycastSort
+{
+	bool operator() (const PointedThing &pt1, const PointedThing &pt2) const;
+};
+
+//! Describes the state of a raycast.
+class RaycastState
+{
+public:
+	/*!
+	 * Creates a raycast.
+	 * @param objects_pointable if false, only nodes will be found
+	 * @param liquids pointable if false, liquid nodes won't be found
+	 */
+	RaycastState(const core::line3d<f32> &shootline, bool objects_pointable,
+		bool liquids_pointable);
+
+	//! Shootline of the raycast.
+	core::line3d<f32> m_shootline;
+	//! Iterator to store the progress of the raycast.
+	voxalgo::VoxelLineIterator m_iterator;
+	//! Previous tested node during the raycast.
+	v3s16 m_previous_node;
+
+	/*!
+	 * This priority queue stores the found pointed things
+	 * waiting to be returned.
+	 */
+	std::priority_queue<PointedThing, std::vector<PointedThing>, RaycastSort> m_found;
+
+	bool m_objects_pointable;
+	bool m_liquids_pointable;
+
+	//! The code needs to search these nodes around the center node.
+	core::aabbox3d<s16> m_search_range { 0, 0, 0, 0, 0, 0 };
+
+	//! If true, the Environment will initialize this state.
+	bool m_initialization_needed = true;
+};
 
 /*!
  * Checks if a line and a box intersects.

src/script/cpp_api/s_item.h

@@ -52,6 +52,7 @@ public:
 protected:
 	friend class LuaItemStack;
 	friend class ModApiItemMod;
+	friend class LuaRaycast;
 
 	bool getItemCallback(const char *name, const char *callbackname);
 	void pushPointedThing(const PointedThing& pointed);

src/script/lua_api/l_env.cpp

@@ -131,6 +131,105 @@ void LuaLBM::trigger(ServerEnvironment *env, v3s16 p, MapNode n)
 	lua_pop(L, 1); // Pop error handler
 }
 
+int LuaRaycast::l_next(lua_State *L)
+{
+	MAP_LOCK_REQUIRED;
+
+	ScriptApiItem *script = getScriptApi<ScriptApiItem>(L);
+	GET_ENV_PTR;
+
+	LuaRaycast *o = checkobject(L, 1);
+	PointedThing pointed;
+	env->continueRaycast(&o->state, &pointed);
+	if (pointed.type == POINTEDTHING_NOTHING)
+		lua_pushnil(L);
+	else
+		script->pushPointedThing(pointed);
+
+	return 1;
+}
+
+int LuaRaycast::create_object(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	bool objects = true;
+	bool liquids = false;
+
+	v3f pos1 = checkFloatPos(L, 1);
+	v3f pos2 = checkFloatPos(L, 2);
+	if (lua_isboolean(L, 3)) {
+		objects = lua_toboolean(L, 3);
+	}
+	if (lua_isboolean(L, 4)) {
+		liquids = lua_toboolean(L, 4);
+	}
+
+	LuaRaycast *o = new LuaRaycast(core::line3d<f32>(pos1, pos2),
+		objects, liquids);
+
+	*(void **) (lua_newuserdata(L, sizeof(void *))) = o;
+	luaL_getmetatable(L, className);
+	lua_setmetatable(L, -2);
+	return 1;
+}
+
+LuaRaycast *LuaRaycast::checkobject(lua_State *L, int narg)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	luaL_checktype(L, narg, LUA_TUSERDATA);
+	void *ud = luaL_checkudata(L, narg, className);
+	if (!ud)
+		luaL_typerror(L, narg, className);
+	return *(LuaRaycast **) ud;
+}
+
+int LuaRaycast::gc_object(lua_State *L)
+{
+	LuaRaycast *o = *(LuaRaycast **) (lua_touserdata(L, 1));
+	delete o;
+	return 0;
+}
+
+void LuaRaycast::Register(lua_State *L)
+{
+	lua_newtable(L);
+	int methodtable = lua_gettop(L);
+	luaL_newmetatable(L, className);
+	int metatable = lua_gettop(L);
+
+	lua_pushliteral(L, "__metatable");
+	lua_pushvalue(L, methodtable);
+	lua_settable(L, metatable);
+
+	lua_pushliteral(L, "__index");
+	lua_pushvalue(L, methodtable);
+	lua_settable(L, metatable);
+
+	lua_pushliteral(L, "__gc");
+	lua_pushcfunction(L, gc_object);
+	lua_settable(L, metatable);
+
+	lua_pushliteral(L, "__call");
+	lua_pushcfunction(L, l_next);
+	lua_settable(L, metatable);
+
+	lua_pop(L, 1);
+
+	luaL_openlib(L, 0, methods, 0);
+	lua_pop(L, 1);
+
+	lua_register(L, className, create_object);
+}
+
+const char LuaRaycast::className[] = "Raycast";
+const luaL_Reg LuaRaycast::methods[] =
+{
+	luamethod(LuaRaycast, next),
+	{ 0, 0 }
+};
+
 void LuaEmergeAreaCallback(v3s16 blockpos, EmergeAction action, void *param)
 {
 	ScriptCallbackState *state = (ScriptCallbackState *)param;
@@ -904,6 +1003,11 @@ int ModApiEnvMod::l_fix_light(lua_State *L)
 	return 1;
 }
 
+int ModApiEnvMod::l_raycast(lua_State *L)
+{
+	return LuaRaycast::create_object(L);
+}
+
 // emerge_area(p1, p2, [callback, context])
 // emerge mapblocks in area p1..p2, calls callback with context upon completion
 int ModApiEnvMod::l_emerge_area(lua_State *L)
@@ -1155,6 +1259,7 @@ void ModApiEnvMod::Initialize(lua_State *L, int top)
 	API_FCT(spawn_tree);
 	API_FCT(find_path);
 	API_FCT(line_of_sight);
+	API_FCT(raycast);
 	API_FCT(transforming_liquid_add);
 	API_FCT(forceload_block);
 	API_FCT(forceload_free_block);

src/script/lua_api/l_env.h

@@ -22,6 +22,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "lua_api/l_base.h"
 #include "serverenvironment.h"
+#include "raycast.h"
 
 class ModApiEnvMod : public ModApiBase {
 private:
@@ -159,6 +160,9 @@ private:
 	// line_of_sight(pos1, pos2, stepsize) -> true/false
 	static int l_line_of_sight(lua_State *L);
 
+	// raycast(pos1, pos2, objects, liquids) -> Raycast
+	static int l_raycast(lua_State *L);
+
 	// find_path(pos1, pos2, searchdistance,
 	//     max_jump, max_drop, algorithm) -> table containing path
 	static int l_find_path(lua_State *L);
@@ -245,6 +249,47 @@ public:
 	virtual void trigger(ServerEnvironment *env, v3s16 p, MapNode n);
 };
 
+//! Lua wrapper for RaycastState objects
+class LuaRaycast : public ModApiBase
+{
+private:
+	static const char className[];
+	static const luaL_Reg methods[];
+	//! Inner state
+	RaycastState state;
+
+	// Exported functions
+
+	// garbage collector
+	static int gc_object(lua_State *L);
+
+	/*!
+	 * Raycast:next() -> pointed_thing
+	 * Returns the next pointed thing on the ray.
+	 */
+	static int l_next(lua_State *L);
+public:
+	//! Constructor with the same arguments as RaycastState.
+	LuaRaycast(
+		const core::line3d<f32> &shootline,
+		bool objects_pointable,
+		bool liquids_pointable) :
+		state(shootline, objects_pointable, liquids_pointable)
+	{}
+
+	//! Creates a LuaRaycast and leaves it on top of the stack.
+	static int create_object(lua_State *L);
+
+	/*!
+	 * Returns the Raycast from the stack or throws an error.
+	 * @param narg location of the RaycastState in the stack
+	 */
+	static LuaRaycast *checkobject(lua_State *L, int narg);
+
+	//! Registers Raycast as a Lua userdata type.
+	static void Register(lua_State *L);
+};
+
 struct ScriptCallbackState {
 	ServerScripting *script;
 	int callback_ref;

src/script/scripting_server.cpp

@@ -92,6 +92,7 @@ void ServerScripting::InitializeModApi(lua_State *L, int top)
 	LuaPerlinNoiseMap::Register(L);
 	LuaPseudoRandom::Register(L);
 	LuaPcgRandom::Register(L);
+	LuaRaycast::Register(L);
 	LuaSecureRandom::Register(L);
 	LuaVoxelManip::Register(L);
 	NodeMetaRef::Register(L);

src/serverenvironment.cpp

@@ -30,7 +30,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "remoteplayer.h"
 #include "scripting_server.h"
 #include "server.h"
-#include "voxelalgorithms.h"
 #include "util/serialize.h"
 #include "util/basic_macros.h"
 #include "util/pointedthing.h"
@@ -1662,6 +1661,38 @@ ActiveObjectMessage ServerEnvironment::getActiveObjectMessage()
 	return message;
 }
 
+void ServerEnvironment::getSelectedActiveObjects(
+	const core::line3d<f32> &shootline_on_map,
+	std::vector<PointedThing> &objects)
+{
+	std::vector<u16> objectIds;
+	getObjectsInsideRadius(objectIds, shootline_on_map.start,
+		shootline_on_map.getLength() + 10.0f);
+	const v3f line_vector = shootline_on_map.getVector();
+
+	for (u32 i = 0; i < objectIds.size(); i++) {
+		ServerActiveObject* obj = getActiveObject(objectIds[i]);
+
+		aabb3f selection_box;
+		if (!obj->getSelectionBox(&selection_box))
+			continue;
+
+		v3f pos = obj->getBasePosition();
+
+		aabb3f offsetted_box(selection_box.MinEdge + pos,
+			selection_box.MaxEdge + pos);
+
+		v3f current_intersection;
+		v3s16 current_normal;
+		if (boxLineCollision(offsetted_box, shootline_on_map.start, line_vector,
+				&current_intersection, &current_normal)) {
+			objects.push_back(PointedThing(
+				(s16) objectIds[i], current_intersection, current_normal,
+				(current_intersection - shootline_on_map.start).getLengthSQ()));
+		}
+	}
+}
+
 /*
 	************ Private methods *************
 */

src/serverenvironment.h

@@ -284,6 +284,11 @@ public:
 	*/
 	ActiveObjectMessage getActiveObjectMessage();
 
+	virtual void getSelectedActiveObjects(
+		const core::line3d<f32> &shootline_on_map,
+		std::vector<PointedThing> &objects
+	);
+
 	/*
 		Activate objects and dynamically modify for the dtime determined
 		from timestamp and additional_dtime

src/util/pointedthing.cpp

@@ -23,19 +23,46 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "../exceptions.h"
 #include <sstream>
 
+PointedThing::PointedThing(const v3s16 &under, const v3s16 &above,
+	const v3s16 &real_under, const v3f &point, const v3s16 &normal,
+	f32 distSq):
+	type(POINTEDTHING_NODE),
+	node_undersurface(under),
+	node_abovesurface(above),
+	node_real_undersurface(real_under),
+	intersection_point(point),
+	intersection_normal(normal),
+	distanceSq(distSq)
+{}
+
+PointedThing::PointedThing(s16 id, const v3f &point, const v3s16 &normal,
+	f32 distSq) :
+	type(POINTEDTHING_OBJECT),
+	object_id(id),
+	intersection_point(point),
+	intersection_normal(normal),
+	distanceSq(distSq)
+{}
+
 std::string PointedThing::dump() const
 {
 	std::ostringstream os(std::ios::binary);
-	if (type == POINTEDTHING_NOTHING) {
+	switch (type) {
+	case POINTEDTHING_NOTHING:
 		os << "[nothing]";
-	} else if (type == POINTEDTHING_NODE) {
+		break;
+	case POINTEDTHING_NODE:
+	{
 		const v3s16 &u = node_undersurface;
 		const v3s16 &a = node_abovesurface;
-		os<<"[node under="<<u.X<<","<<u.Y<<","<<u.Z
+		os << "[node under=" << u.X << "," << u.Y << "," << u.Z << " above="
-			<< " above="<<a.X<<","<<a.Y<<","<<a.Z<<"]";
+			<< a.X << "," << a.Y << "," << a.Z << "]";
-	} else if (type == POINTEDTHING_OBJECT) {
+	}
+		break;
+	case POINTEDTHING_OBJECT:
 		os << "[object " << object_id << "]";
-	} else {
+		break;
+	default:
 		os << "[unknown PointedThing]";
 	}
 	return os.str();
@@ -104,4 +131,3 @@ bool PointedThing::operator!=(const PointedThing &pt2) const
 {
 	return !(*this == pt2);
 }
-

src/util/pointedthing.h

@@ -58,6 +58,11 @@ struct PointedThing
 	 * point of the collision and the nodebox of the node.
 	 */
 	v3s16 node_real_undersurface;
+	/*!
+	 * Only valid if type is POINTEDTHING_OBJECT.
+	 * The ID of the object the ray hit.
+	 */
+	s16 object_id = -1;
 	/*!
 	 * Only valid if type isn't POINTEDTHING_NONE.
 	 * First intersection point of the ray and the nodebox.
@@ -71,12 +76,19 @@ struct PointedThing
 	 */
 	v3s16 intersection_normal;
 	/*!
-	 * Only valid if type is POINTEDTHING_OBJECT.
+	 * Square of the distance between the pointing
-	 * The ID of the object the ray hit.
+	 * ray's start point and the intersection point.
 	 */
-	s16 object_id = -1;
+	f32 distanceSq = 0;
 
+	//! Constructor for POINTEDTHING_NOTHING
 	PointedThing() {};
+	//! Constructor for POINTEDTHING_NODE
+	PointedThing(const v3s16 &under, const v3s16 &above,
+		const v3s16 &real_under, const v3f &point, const v3s16 &normal,
+		f32 distSq);
+	//! Constructor for POINTEDTHING_OBJECT
+	PointedThing(s16 id, const v3f &point, const v3s16 &normal, f32 distSq);
 	std::string dump() const;
 	void serialize(std::ostream &os) const;
 	void deSerialize(std::istream &is);

src/voxelalgorithms.cpp

@@ -1407,6 +1407,8 @@ VoxelLineIterator::VoxelLineIterator(const v3f &start_position, const v3f &line_
 	m_line_vector(line_vector)
 {
 	m_current_node_pos = floatToInt(m_start_position, 1);
+	m_start_node_pos = m_current_node_pos;
+	m_last_index = getIndex(floatToInt(start_position + line_vector, 1));
 
 	if (m_line_vector.X > 0) {
 		m_next_intersection_multi.X = (floorf(m_start_position.X - 0.5) + 1.5
@@ -1440,14 +1442,11 @@ VoxelLineIterator::VoxelLineIterator(const v3f &start_position, const v3f &line_
 		m_intersection_multi_inc.Z = -1 / m_line_vector.Z;
 		m_step_directions.Z = -1;
 	}
-
-	m_has_next = (m_next_intersection_multi.X <= 1)
-		|| (m_next_intersection_multi.Y <= 1)
-		|| (m_next_intersection_multi.Z <= 1);
 }
 
 void VoxelLineIterator::next()
 {
+	m_current_index++;
 	if ((m_next_intersection_multi.X < m_next_intersection_multi.Y)
 			&& (m_next_intersection_multi.X < m_next_intersection_multi.Z)) {
 		m_next_intersection_multi.X += m_intersection_multi_inc.X;
@@ -1459,10 +1458,13 @@ void VoxelLineIterator::next()
 		m_next_intersection_multi.Z += m_intersection_multi_inc.Z;
 		m_current_node_pos.Z += m_step_directions.Z;
 	}
+}
 
-	m_has_next = (m_next_intersection_multi.X <= 1)
+s16 VoxelLineIterator::getIndex(v3s16 voxel){
-			|| (m_next_intersection_multi.Y <= 1)
+	return
-			|| (m_next_intersection_multi.Z <= 1);
+		abs(voxel.X - m_start_node_pos.X) +
+		abs(voxel.Y - m_start_node_pos.Y) +
+		abs(voxel.Z - m_start_node_pos.Z);
 }
 
 } // namespace voxalgo

src/voxelalgorithms.h

@@ -123,21 +123,25 @@ public:
 	 * which multiplying the line's vector gives a vector that ends
 	 * on the intersection of two nodes.
 	 */
-	v3f m_next_intersection_multi = v3f(10000.0f, 10000.0f, 10000.0f);
+	v3f m_next_intersection_multi { 10000.0f, 10000.0f, 10000.0f };
 	/*!
 	 * Each component stores the smallest positive number, by which
 	 * m_next_intersection_multi's components can be increased.
 	 */
-	v3f m_intersection_multi_inc = v3f(10000.0f, 10000.0f, 10000.0f);
+	v3f m_intersection_multi_inc { 10000.0f, 10000.0f, 10000.0f };
 	/*!
 	 * Direction of the line. Each component can be -1 or 1 (if a
 	 * component of the line's vector is 0, then there will be 1).
 	 */
-	v3s16 m_step_directions = v3s16(1, 1, 1);
+	v3s16 m_step_directions { 1, 1, 1 };
 	//! Position of the current node.
 	v3s16 m_current_node_pos;
-	//! If true, the next node will intersect the line, too.
+	//! Index of the current node
-	bool m_has_next;
+	s16 m_current_index = 0;
+	//! Position of the start node.
+	v3s16 m_start_node_pos;
+	//! Index of the last node
+	s16 m_last_index;
 
 	/*!
 	 * Creates a voxel line iterator with the given line.
@@ -161,7 +165,18 @@ public:
 	/*!
 	 * Returns true if the next voxel intersects the given line.
 	 */
-	inline bool hasNext() const { return m_has_next; }
+	inline bool hasNext() const
+	{
+		return m_current_index < m_last_index;
+	}
+
+	/*!
+	 * Returns how many times next() must be called until
+	 * voxel==m_current_node_pos.
+	 * If voxel does not intersect with the line,
+	 * the result is undefined.
+	 */
+	s16 getIndex(v3s16 voxel);
 };
 
 } // namespace voxalgo