In a landscape there are many things that might be distributed around the scene: Trees, rocks, sheep, flowers, patches of grass to name a few. The Distribution shader provides a means to do just that. The sample project file for this post can be downloaded here. This shader lets you determine how much of the surface should be covered by it (Coverage) and how regular or fractalized the coverage should be (Fractal breakup). In the sample project, we first edit the Base colours shader to draw the underlying terrain in grey, then use a Distribution shader to add green patches (simulating for example moss growing on stone).
Looks good so far. Now let’s simulate little purple flowers by adding another Distribution shader on top of the green one with, you guessed it, a nice purple.
Here’s what it looks like up closer (note the use of fractal technology allows us to zoom way in, giving almost endless detail both for the terrain and for the colors covering it).
The Distribution shader has the Altitude constraints and Slope constraints available in the Surface shader.