Overlays are similar to decals but you can control the scale, rotation, and faces that they are applied to. With this greater power comes a greater cost; overlays take up a greater percentage of processing power as compared with a decal. However, they cannot be toggled on and off, so they will always stay where they are.

You place an overlay in the same manner that decals are placed—grab the overlay tool (a brick cube with grass top), select an overlay texture, and then click on a face in the 3D view to apply an overlay entity. Once an overlay is created, you can then modify the scale and rotation just like any normal brush in the 2D view. In the 3D view, you have control over each corner of the overlay. Move the corners around to change the shape of the overlay to suit your needs. Again, normal textures can be applied as overlays, but the end result might not be as expected.