# Navigation

We implement [Recast Navigation](https://github.com/recastnavigation/recastnavigation) in s&box, the industry standard for navmesh generation and navigation agents. It's used in Unreal, Unity and Godot. So if it seems familiar, that's why.


![](https://cdn.sbox.game/doc/systems/navigation/images/navigation.jpg)


# What is a NavMesh?

A NavMesh is a simplified map of traversable areas in a game world, designed to help AI with pathfinding and movement. NavMeshes are created from the game's **PhysicsWorld**, which defines where AI characters are allowed to move.

## Understanding NavMesh Limitations

A NavMesh **is not** a detailed or precise representation of the game world; rather, it is a simplified abstraction focused solely on navigable areas. **It lacks exact height information** or precise ground geometry. Use the PhysiscsWorld alongside the NavMesh, for interactions that require specific physical details, such as placing the game object on the ground.

# Creating a NavMesh

To create a NavMesh in your scene, just click the Enable NavMesh button in the header.

![](https://cdn.sbox.game/doc/systems/navigation/images/creating-a-navmesh.png)

You can toggle viewing the generated mesh by clicking the button next to it.


![When the mesh is visible, it will update live in the scene editor 1698x940](https://cdn.sbox.game/doc/systems/navigation/images/when-the-mesh-is-visible-it-will-update-live-in-the-scene-ed.mp4)


The NavMeshis split up into multiple smaller tiles. The ==yellow== lines represent regular polygon boundaries, while the ==blue== lines represent polygon borders that are also tile boundaries.


# NavMesh Settings

You can edit further NavMesh settings by clicking the pencil and paper icon in the NavMesh group in the header.

![](https://cdn.sbox.game/doc/systems/navigation/images/navmesh-settings.png)

This allows you to adjust the properties of the mesh, like how steep slopes can be. You can also filter which physics objects are used when generating the mesh.


# Code

The navmesh is accessible at `Scene.NavMesh`.

```csharp
// Get a random position anywhere the navmesh
var pos = Scene.NavMesh.GetRandomPoint();

// Get a random position within radius of testposition
var pos = Scene.NavMesh.GetRandomPoint( testposition, radius );

// Get the closest point on the navmesh from another position
var pos = Scene.NavMesh.GetClosestPoint( testposition );

// Get the closest edge of the navmesg from this position
var pos = Scene.NavMesh.GetClosestEdge( testposition );

// Get a path from one position to another
var path = Scene.NavMesh.CalculatePath( new CalculatePathRequest()
{
	Agent = Agent, // Optional agent to use for parameters
    Start = WorldPosition,
    Target = TargetWorldPosition
} );

// Path.Status is either Complete or Partial
if ( path.IsValid() ) // ...

// Mark the navmesh dirty, so it will be rebuilt in the background
Scene.NavMesh.SetDirty();
```