Difficulty Implementing A* Algorithm for Pathfinding in Unity - Heuristic Function Seems Ineffective
I'm collaborating on a project where I'm stuck on something that should probably be simple. I've been trying to implement the A* pathfinding algorithm in Unity for a grid-based game, but I'm running into issues with the heuristic function not guiding my pathfinding as expected. My approach utilizes a simple Manhattan distance heuristic since my grid only allows movement in four directions (up, down, left, right). However, the paths generated are often longer than necessary, and sometimes the algorithm even chooses paths that seem illogical. I've set up my Node class to hold the necessary properties like `gCost`, `hCost`, and `fCost`, and I'm calculating them in the following way: ```csharp public class Node { public Vector2Int Position; public float gCost; public float hCost; public float fCost; public Node Parent; public float CalculateHCost(Vector2Int targetPosition) { return Mathf.Abs(Position.x - targetPosition.x) + Mathf.Abs(Position.y - targetPosition.y); } } ``` When I'm expanding nodes during the search, I seem to be getting backtracking paths that are longer than what I see visually in the game. For example, if I have a target directly to the right, and the only obstacle is one tile down, it sometimes chooses a longer route around instead of going directly right. I've tried debugging by printing the `gCost`, `hCost`, and `fCost` for every node processed, but they appear to be calculated correctly based on my logic. Here's a snippet of how I'm handling node expansion: ```csharp foreach (var neighbor in GetNeighbors(currentNode)) { float newGCost = currentNode.gCost + GetDistance(currentNode.Position, neighbor.Position); if (newGCost < neighbor.gCost || !openSet.Contains(neighbor)) { neighbor.gCost = newGCost; neighbor.hCost = neighbor.CalculateHCost(targetPosition); neighbor.fCost = neighbor.gCost + neighbor.hCost; neighbor.Parent = currentNode; if (!openSet.Contains(neighbor)) { openSet.Add(neighbor); } } } ``` What's baffling is that even when I lower the heuristic weight, I still observe inefficient paths being chosen. I suspect I might be missing something regarding the node prioritization in my open set or the way I'm calculating costs, but I need to pinpoint the scenario. Has anyone experienced similar issues with A* in Unity or can offer insight into how to debug this effectively? Any tips or best practices would be greatly appreciated! This is part of a larger service I'm building. How would you solve this? I'm coming from a different tech stack and learning Csharp. Any ideas what could be causing this?