This lesson will explain how you can use the foliage tool to add objects to your terrain. These will not have collisions (by default) and will be made to work better on a machine than just adding lots of objects.
In the Properties window with the terrain selected, click the tab next to Paint called Foliage
grassto find Grass Tall.
You should have grass springing up on your terrain as soon as you add the object. Click on the object image that appears now in the Foliage tab to see its customizable properties.
Next, we’re going to change the river to look more like a marsh by filling it with tall grasses.
Hint: If foliage is spawning in unexpected places, use the Show Debug Material option in the Paint terrain Palette menu to check which material is being applied in any area of the terrain.
If you are placing trees or rocks with foliage, the player can walk through them. You can enable collision by selecting foliage and clicking on the “Enable Collision” checkbox.