What I want to achieve is actually masking the grass node in the material, so make grass not spawn where other meshes are near, so it won’t spawn in the floor of a building etc.
This is the cube in the ground:
I lerp with the mask based on the DistanceToNearestSurface node between red and blue, so the mask is really good (I would really like to see a “Gaussian Smoothing” material node, I would use it so often :rolleyes:).
Now I try to do this:
And it would actually work, but after testing with a manual alpha value I noticed the grass only updates after I hit “apply” in the material again and I can’t change the alpha e.g. in a material instance, changing it after the material is “compiled” does not update the grass 
Would have been so awesome if it would have worked… 