# Runtime Modification

You can of course modify maps at runtime. Here's a simple example code which will add new cells to a layer and execute a build process.

Please have a look at following samples for a more advanced approach:

* Deep Rock Crystals URP
* Runtime Editor URP

Refer to the API documentation for more:

{% content-ref url="api" %}
[api](https://giantgrey.gitbook.io/tileworldcreator-v4-documentation/api)
{% endcontent-ref %}

## Namespace

```csharp
using GiantGrey.TileWorldCreator;
```

## Add & Remove Cells at runtime

```csharp
public TileWorldCreatorManager manager;

// Register to blueprint layers ready event
// So we can then execute the build layers.
void OnEnable()
{
    manager.OnBlueprintLayersReady += BuildMap;
}
		 
void OnDisable()
{
    manager.OnBlueprintLayersReady -= BuildMap;
}
		
		
public void AddCells()
{
    HashSet<Vector2> positions = new HashSet<Vector2>;
    
    // Add some positions
    positions.Add(new Vector2(0.0f, 1.0f));
    positions.Add(new Vector2(0.0f, 2.0f));
    positions.Add(new Vector2(1.0f, 1.0f));
    positions.Add(new Vector2(1.0f, 2.0f));
    
    // Add cells to a layer (MyLayer)
    manager.AddCellsToLayer("MyLayer", positions);
    
    // Remove cells from a layer (MyLayer)
    //manager.RemoveCellsFromLayer("MyLayer", positions);
    
    // Execute all blueprint layers
    manager.ExecuteBlueprintLayers();
}

// As soon as blueprint layers are ready, we call the ExecuteAllBuildLayers
void BuildMap()
{
    manager.ExecuteBuildLayers(ExecutionMode.Normal);
}
```