Creates a model of a 3D Hilbert curve, suitable for 3D printing.

make.py

#!/usr/bin/env python3
# Creates a model of a 3D Hilbert curve, suitable for 3D printing.
# by Andrew Brampton (bramp.net) 2023
# See https://www.printables.com/model/518431
#
# Usage:
#   python3 make.py 4 4 4 --voxelizer voxelmap --spacing 3
#   python3 make.py 4 4 4 --voxelizer trimesh --spacing 2
#

from gilbert import gilbert3d  
import numpy as np
import argparse

def vxmVoxel(array):
	"""Uses MarchingMesh and tends to create diamond shaped tunneled."""
	import voxelmap as vxm

	model = vxm.Model()
	model.array = array

	print('Display as a voxel')
	#model.draw(wireframe=True, background_color='#3e404e',window_size=[1024,1024])

	print('Convert to mesh')
	model.MarchingMesh(method="lewiner")
	model.MeshView(wireframe=True,alpha=1,background_color='#b064fd',viewport=[1024,1024])


def trimeshVoxel(array):
	"""Uses as_boxes and creates square shaped tunneled."""

	from trimesh import voxel as v

	voxels = v.VoxelGrid(array)

	print('Convert to mesh (saved as trimesh.obj)')
	boxes = voxels.as_boxes()
	boxes.export("trimesh.obj")
	boxes.show()
	#voxels.marching_cubes.show()

def cmp(a, b):
	return (a > b) - (a < b)

def line(a, start, end, value):
	"""Very quick and dirty 3D line drawing in steps of 1"""
	while start != end:
		a[start] = value
		start = (
			start[0] - cmp(start[0], end[0]), 
			start[1] - cmp(start[1], end[1]), 
			start[2] - cmp(start[2], end[2])
		)
	a[start] = value

if __name__ == "__main__":

	parser = argparse.ArgumentParser()
	parser.add_argument('width', type=int)
	parser.add_argument('height', type=int)
	parser.add_argument('depth', type=int)

	parser.add_argument('--margin', default=1, type=int)
	parser.add_argument('--spacing', default=3, type=int)

	parser.add_argument('--voxelizer', choices=["voxelmap", "trimesh"], default="voxelmap")

	args = parser.parse_args()

	array = np.zeros((
		args.width  * args.spacing + 2*args.margin, 
		args.height * args.spacing + 2*args.margin, 
		args.depth  * args.spacing + 2*args.margin,
	))

	last = None

	for x, y, z in gilbert3d.gilbert3d(args.width, args.height, args.depth):
		cur = (
			x * args.spacing + args.margin,
			y * args.spacing + args.margin,
			z * args.spacing + args.margin,
		)

		if last != None:
			# Draw line from las to cur
			line(array, last, cur, 1)

		last = cur

	if args.voxelizer == "voxelmap":
		vxmVoxel(array)
	elif args.voxelizer == "trimesh":
		trimeshVoxel(array)
	else:
		print("unknown voxel engine")