sample from landscape layer?

heey there…
i was wondering if it is possible to sample from a landscape layer based upon position and do stuff with it in the material editor.
to clarify:
I have a landscape with some painted layers and I have a few objects. In order to blend the objects nice with the landscape I would like to have the objects make use of the landscape layers as well.

For example:
If I drag a modeled rock in the sand area it will become sand. If I drag it to a more stone area, this model become stone.

How it makes sense.

Regards! T

something like

Not entirely, i am looking for a way / node to have a material ‘talking’ to a landscape layer. That material wont be assigned to a landscape.