# 02 How Pathfinding Works

Plain English version.

## The algorithm

OWP uses **A\*** — the same algorithm Unreal's NavMesh uses. From start node to goal node, it explores the cheapest combination of paths.

## What "cheap" means

Each path has a **cost** that the pathfinder sees. Roughly:

```
Cost = Length / Speed × Cost Multiplier × (zones, conditions, congestion)
```

Translation:

* **Long paths** cost more.
* **Fast paths** cost less.
* **Cost Multiplier > 1** makes a path less attractive.
* **Zones** (Speed/Blocked/Danger) modify cost in their volumes.
* **Conditions** can add penalties or block entirely.
* **Congestion** (path filling up) raises cost when many AIs are on it.

## Blocked vs. Penalized

* **Blocked** path is invisible to the pathfinder — never used, even as a last resort.
* **Penalized** path is still legal — used if no cheaper alternative exists.

## Disconnected networks

If start and goal are not connected, pathfinding fails with `Unreachable`. Use **Validator** or **Merge Networks** to fix.

## Free Pathfind

Normal pathfinding works node → node. **Free Pathfind** lets you go from any world point to any other world point: it adds NavMesh entry/exit segments. Great for vehicles joining a road from a parking lot and leaving it later.

## Should I worry about performance?

Probably not. A\* runs in microseconds for typical networks (hundreds to a few thousand nodes). Don't call **Find Path** every frame from Tick — call it once when the goal changes and reuse the result.


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