Determining drainage constraints and geometries in a triangular mesh

A computer-implemented system for designing a terrain surface, comprising:

• (a) a computer having a memory;
• (b) a processor executing on the computer;
• (c) the memory storing a set of instructions, wherein the set of instructions, when executed by the processor cause the processor to perform operations comprising:
• (i) obtaining a triangular surface mesh representative of an existing surface, wherein the triangular surface mesh comprises two or more triangles that are connected by vertices and edges;
• (ii) specifying a drain intention for the terrain surface through one or more geometries, wherein:
• (1) each of the one or more geometries comprises a point or a line;
• and
• (2) the drain intention defines a drainage flow that influences a shape of the terrain surface;
• (iii) modifying the triangular surface mesh using a Voronoi diagram resulting in a modified triangular surface mesh, wherein:
• (1) the Voronoi diagram is based on the one or more geometries;
• and
• (2) the modifying prevents a drain conflict between the two or more triangles;
• (iv) autonomously determining a drain direction of each of the two or more triangles in the modified triangular surface mesh based on the drain intention, wherein the autonomously determining generates a drain pattern that is used to shape the terrain surface.