I built a Material that displaces a Plane with a Noise-Texture. Then I take the Normals form the faces and dependend on that the Material sets an Image-Texture (gras on the flater parts or rock on the steeper parts). For that desicion I use a Normal-Node compared with a Color-Ramp-Node. I plan to use a particle system for planting gras and trees. Is it possible to use that Material to define where the particles are alowed and where not?