Add/Remove/Modify Terrain Brushes

Documentation for Unity Asset Store version v1.20

Terrain Brush Textures

Terrain brushes are defined in the 'Brushes' array property of the 'LE_ConfigTerrain', which is attached to the 'LE_LevelEditorMain' instance contained in the level editor scene. Terrain brushes are simple RGBA textures. The RGB color channel of a terrain brush texture has to be full white. The alpha channel defines the brush amount where 1 is the full brush value and 0 is no brush at all. A brush texture must have a one pixel border in its alpha channel. The border must have the value of 0 in its alpha channel. If you encounter any projector problems with your custom brush, where the brush texture is drawn all over the terrain you will need to make the 0 alpha channel border wider. Use exact the same import settings like they are used for the built-in brushes.

You can find free brush textures here: Generic Terrain Brushes by FlamingSands on the Unity Asset Store.