Hello everyone, I have a very complex topography, in the form of a mesh, but supposing I could patch the contour curves and generate a surface, are there any resources out there that do what I stated in the title? And if not, a hint on where to start would be of great help.

Ideally I would pick two points on the surface, or even contour lines. A, B, and generate a polyline that connects successive points that are always below the previous point. The idea is that this line will be a canal of water that travels because of gravity, hence the slope can never be positive.

To clarify, I am not talking about flow lines, I am talking about a single polyline. If the possibilities to go from A and B with ever decreasing height path, then the shortest or longest criteria could be used to pick the points.