I need a system that generates trees with varying density (depending on biome, slope, etc.), with guaranteed minimal distance between trees, and then chooses which 3D model to use for each tree. All this can be done statically (at world generation) as long as I can remove some trees (when cutting them down). And I need to access very distant instances, even if terrain is not generated at that place.Then I need fine granularity for managing LODs of close trees, but also very distant impostors.