[WIP] A footprint system that works with ANY slope-based material

Quick demo:

PROBLEM: slope-based materials are widely used nowadays to automatically paint landscapes. As we already know, one layer is bounded to have *one and only one *Phys Material associated to it.
The consequence is that you are not able to detect the different surfaces because the engine just sees only one Phys Material, when in reality that layer is representing something like grass, mud and rock according to the slope parameters.

SOLUTION: this footprint system aims to overcome this “limitation” by enabling the user to fire different sounds, decals and emitters on ANY slope-based material. No need to modify the slope-based material or even touching its parameters, this solution is completely independent so it’s really compatible with all the slope-based material out there.

Actually this work is at advanced stage, not just a WIP, but if you have any suggestions and/or feature requests, please let me know.