In this example, the Flatten tool is being used in the middle of the hillside to flatten out areas at the point where the mouse click was initiated. As long as the mouse is held down, the height value
that was detected is used along any surface to raise or lower (depending on your tool settings) to that height.
Use the following controls to sculpt your Landscape heightmap:
Left Mouse Button
Flattens or levels by both raising and lowering or individually raising and lowering the heightmap.