Using pass system for nodes instead of state field.

Housekeeping.

demo/bin/multilevel_astar.gd

@@ -51,6 +51,11 @@ func set_terrain(point: Vector2i, type: MultilevelAStarEx.TerrainType) -> void:
 	_astar.set_terrain(point, type)
 
 
+func is_blocked(point: Vector2i) -> bool:
+	assert(_used_rect.has_point(point))
+	return (_astar.get_terrain(point) == MultilevelAStarEx.BLOCKED) or _astar.get_unit(point)
+
+
 func find_path(from: Vector2i, to: Vector2i, return_closest: bool = false) -> Array[Vector2i]:
 	assert(_used_rect.has_point(from))
 	assert(_used_rect.has_point(to))

src/MultilevelAStarEx.cpp

@@ -17,18 +17,23 @@ using namespace godot;
 static const int STRAIGHT_DISTANCE = 10;
 static const int DIAGONAL_DISTANCE = 14;
 
-Node::Node() { }
+Node::Node()
+{
+	this->openPass = 0;
+	this->closedPass = 0;
+}
 
-Node::Node(int x, int y)
+Node::Node(int x, int y) : Node()
 {
 	this->x = x;
 	this->y = y;
-	this->state = UNUSED;
 }
 
-void Node::init(Node *parent, int distanceFromStart, const Vector2i &end)
+void Node::open(int pass, Node *parent, int distanceFromStart, const Vector2i &end)
 {
-	this->state = OPEN;
+	DEV_ASSERT(this->openPass != pass);
+
+	this->openPass = pass;
 	this->parent = parent;
 	this->distanceFromStart = distanceFromStart;
 
@@ -58,6 +63,29 @@ void Node::init(Node *parent, int distanceFromStart, const Vector2i &end)
 	}
 }
 
+void Node::close(int pass)
+{
+	DEV_ASSERT(openPass == pass && closedPass != pass);
+
+	closedPass = pass;
+}
+
+Node::NodeState Node::state(int pass) const
+{
+	if (closedPass == pass)
+	{
+		return CLOSED;
+	}
+	else if (openPass == pass)
+	{
+		return OPEN;
+	}
+	else
+	{
+		return UNUSED;
+	}
+}
+
 int Node::total_cost() const
 {
 	return distanceFromStart + distanceToEnd;
@@ -83,6 +111,7 @@ MultilevelAStarEx::MultilevelAStarEx()
 	//UtilityFunctions::print("Constructor.");
 
 	_init = false;
+	_pass = 0;
 }
 
 MultilevelAStarEx::~MultilevelAStarEx()
@@ -211,29 +240,27 @@ Variant MultilevelAStarEx::find_path(const Vector2i &from, const Vector2i &to, b
 	DEV_ASSERT(_region.has_point(from));
 	DEV_ASSERT(_region.has_point(to));
 
+	_pass++;
+
 	Vector2i from2 = from - _trans;
 	Vector2i to2 = to - _trans;
 
-	Variant result;
-
-	std::vector<Node*> open;
-	std::vector<Node*> closed;
+	std::vector<Node *> open;
 
 	open.reserve(_width * _height);
-	closed.reserve(_width * _height);
 
 	Node *closest = &NODES(from2.x, from2.y);
-	closest->init(nullptr, 0, to2);
+	closest->open(_pass, nullptr, 0, to2);
 	open.push_back(closest);
 
-	auto process = [this, &open, &closed, &to2, &closest](Node *current, int x, int y, int distance) {
+	auto process = [this, &open, &to2, &closest](Node *current, int x, int y, int distance) {
 		Node *node = &NODES(x, y);
-		if (node->state == Node::UNUSED)
+		if (node->state(_pass) == Node::UNUSED)
 		{
-			node->init(current, current->distanceFromStart + distance, to2);
+			node->open(_pass, current, current->distanceFromStart + distance, to2);
 			open.push_back(node);
 		}
-		else if (node->state == Node::OPEN)
+		else if (node->state(_pass) == Node::OPEN)
 		{
 			if (current->distanceFromStart < node->parent->distanceFromStart)
 			{
@@ -256,7 +283,7 @@ Variant MultilevelAStarEx::find_path(const Vector2i &from, const Vector2i &to, b
 		}
 	};
 
-	while (open.size() > 0)
+	while (!open.empty())
 	{
 		// find closest to destination
 		Node *current = open[0];
@@ -271,14 +298,12 @@ Variant MultilevelAStarEx::find_path(const Vector2i &from, const Vector2i &to, b
 		if (current->distanceToEnd == 0)
 		{
 			// found the path
-			result = Variant(generate_path(current));
-			goto cleanup;
+			return Variant(generate_path(current));
 		}
 
 		// close it
-		current->state = Node::CLOSED;
+		current->close(_pass);
 		open.erase(std::remove(open.begin(), open.end(), current), open.end());
-		closed.push_back(current);
 
 		// expand it
 		if (current->x - 1 >= 0) // left
@@ -339,23 +364,11 @@ Variant MultilevelAStarEx::find_path(const Vector2i &from, const Vector2i &to, b
 		}
 	}
 
-	// this is skipped if a path was found
 	if (return_closest)
 	{
 		// return path to closest
-		result = Variant(generate_path(closest));
+		return Variant(generate_path(closest));
 	}
 
-cleanup:
-	// release the nodes
-	for (Node *node : open)
-	{
-		node->state = Node::UNUSED;
-	}
-	for (Node *node : closed)
-	{
-		node->state = Node::UNUSED;
-	}
-
-	return result;
+	return Variant();
 }

src/MultilevelAStarEx.h

@@ -20,7 +20,7 @@ public:
 	};
 
 private:
-	NodeState state;
+	int openPass, closedPass;
 	int x, y;
 
 	Node *parent;
@@ -30,7 +30,9 @@ private:
 	int distanceToEndForClosest;
 
 	Node(int x, int y);
-	void init(Node *parent, int distanceFromStart, const Vector2i &end);
+	void open(int pass, Node *parent, int distanceFromStart, const Vector2i &end);
+	void close(int pass);
+	NodeState state(int pass) const;
 	int total_cost() const;
 
 public:
@@ -51,6 +53,7 @@ public:
 
 private:
 	bool _init;
+	int _pass;
 	std::vector<TerrainType> _terrain;
 	std::vector<bool> _units;
 	std::vector<Node> _nodes;