Create a field out of directions moving away from the nearest shape.

Input parameters:

1. Sh → Collection of shapes. Allowed types are limited to points, planes, curves and surfaces.
2. Ff → Motion falloff as a function of distance.
3. Ln → If true, the fleeing direction only takes into account the nearest shape.
   •  True → Nearest
   • False → All

Output parameters:

1. Fl → Field representing directions fleeing away from shapes.