Create a custom brush that runs a script

Scriptable brushes are brushes that can draw in more ways than the default toolbar, for example draw a line of tiles or random tiles. Scriptable brushes are part of the 2D Tilemap Extras package.

You can do the following:

• Use a prebuilt scriptable brush.
• Create a custom scriptable brush using the GridBrushBase API.

Use a prebuilt scriptable brush

To use a prebuilt scriptable brush, follow these steps:

1. Make sure the 2D Tilemap Extras package is installed in your project. For more information, refer to set up your project for 2D games.
2. Select a tile from the tile palette as normal.
3. In the Brush section, select a brush type other than Default Brush.

For more information about each scriptable brush, refer to Scriptable brushes in the 2D Tilemap Extras package documentation.

Create a custom scriptable brush

1. To create a new C# script, from the main menu select Assets > Create > MonoBehaviour script.

2. Open the script and replace the code with a class that inherits from UnityEngine.Tilemaps.GridBrushBase. For example:

   using UnityEngine;
   using UnityEngine.Tilemaps;
   
   public class MyCustomBrush : GridBrushBase
   {
   }
   

3. Implement the methods of GridBrushBase to define the behavior of the brush. For example, implement the following:

   • Paint to add items to the grid.
   • Erase to remove items from the grid.
   • FloodFill to fill areas on the grid.
   • Rotate to rotate items.
   • Flip to flip items.
   • ChangeZPosition and ResetZPosition to control the 3D height of items in an Isometric Z as Y tilemap.

4. To create instances of your brush as assets in your project, add the CreateAssetMenu attribute before the class declaration.

   using UnityEngine;
   using UnityEngine.Tilemaps;
   
   [CreateAssetMenu]
   public class MyCustomBrush : GridBrushBase
   {
       // ...
   }
   

5. Create an instance of the brush. For example in the previous example, from the main menu, select Assets > My Custom Brush.

The custom brush automatically appears in the Brush Inspector dropdown in the Tile Palette window. For more information, refer to Tile Palette window reference.

Create a custom editor for a scriptable brush

You can also make a custom editor for a custom scriptable brush. This works the same way as custom editors for scriptable objects. The following are the main methods you would want to override when creating a custom editor:

• Override OnPaintInspectorGUI to have an Inspector window appear on the Palette when the Brush is selected to provide additional behaviour when painting.
• Override OnPaintSceneGUI to add additional behaviours when painting on the SceneView.
• Override validTargets to have a custom list of targets which the Brush can interact with. This list of targets is shown as a dropdown list in the Palette window.
• Add a CustomGridBrush attribute to your Scriptable Brush class to change its name, make it the default brush in the project, and other options.
• Add a BrushTools attribute to your class with a list of compatible TilemapEditorTools types. This ensures that your Scriptable Brush only activates with these specific tools from the Tile Palette toolbar.

Examples

Refer to the following for examples of a custom scriptable brush:

• GridBrushBase in the API documentation for a simple example that paints GameObjects instead of tiles.
• Select a prebuilt scriptable brush in the Tile Palette window, then double-click the Script field to open the script and check how the brush is implemented.

Additional resources

• Create a custom tile that runs a script