This is a very general question where I need a bit of help. I am making a scene with an island in it and I would like to populate my island with a forest, but NOT put trees beyond the shore line, or on the top of a mountain. What I'd really like to do, is something similar to the way that a maximum and minimum altitude can be specified for a surface shader and have that affect the object generation. My first thought was that I could perhaps use the object density shader on the population and assign it to an existing surface shader that was already bounded by the desired maximum and minimum altitudes, but this doesn't seem to prevent generation of objects above the maximum altitude (at least), so I think my idea is too simplistic. What's the best way to do something like this?
A follow up harder question, is that I also have a small lake on my island, and I would like to avoid populating trees into that, but ideally get them right up to the shore line. In a perfect world I likt to put one bounding box for my population completely round the island and use a density shader to achieve all the effects described but is this possible? If so how and if not, how would you go about achieving these kind of effects?