Creating Gordon Surfaces

[gumyr]

Discussed in #830

^{Originally posted by jsbroks December 19, 2024}
I'm wondering what is the best way to create a Gordon Surface?

Here is what I have so far but as you would expect I getting Error building a non-planer face with the provided exterior.

import csv
import numpy as np
from build123d import *


def read_heightmap(filename: str):
    with open(filename, 'r') as f:
        reader = csv.reader(f)
        heightmap = []
        for row in reader:
            heightmap.append([float(val) for val in row])
    return np.array(heightmap)


heightmap = read_heightmap('heightmap.csv')

points = []
for x in range(heightmap.shape[0]):
    for y in range(heightmap.shape[1]):
        points.append(Vector(x, y, heightmap[x,y]))


x_splines = []
y_splines = []


for x in range(heightmap.shape[0]):
    points = [(x, y, heightmap[x,y]) for y in range(heightmap.shape[1])]
    x_splines.append(Spline(points))


for y in range(heightmap.shape[1]):
    points = [(x, y, heightmap[x,y]) for x in range(heightmap.shape[0])]
    y_splines.append(Spline(points))

boundary_wire = Wire.make_wire([x_splines[0], y_splines[0], x_splines[-1], y_splines[-1]])

show_object(Face.make_surface(boundary_wire))
```</div>

[gumyr]

From @mnesarco

TiGL[1] has an OpenCascade based Gordon surface builder that is very good (c++). Christophe Grellier (@tomate44) ported it to FreeCAD's Curves WB[2] long time ago in Python. It can be used as a reference to port it to build123d. I am in the process of reorganizing the implementation as a standalone python module, but it is WIP and i can't make compromises on that [3]

[1] https://dlr-sc.github.io/tigl/
[2] https://github.com/tomate44/CurvesWB/blob/master/freecad/Curves/gordon.py
[3] https://github.com/mnesarco/MarzWorkbench/blob/master/freecad/marz/curves/gordon.py