test_mcubes.py

import pytest

import numpy as np
from numpy.testing import assert_array_equal, assert_allclose

import mcubes


def test_empty():

    levelset = np.zeros((50, 50, 50))
    vertices, triangles = mcubes.marching_cubes(levelset, 0.5)

    assert len(vertices) == len(triangles) == 0


def test_sphere():
    x, y, z = np.mgrid[:100, :100, :100]
    u = (x - 50)**2 + (y - 50)**2 + (z - 50)**2 - 25**2

    def func(x, y, z):
        return (x - 50)**2 + (y - 50)**2 + (z - 50)**2 - 25**2

    vertices1, triangles1 = mcubes.marching_cubes(u, 0.0)
    vertices2, triangles2 = mcubes.marching_cubes_func(
        (0, 0, 0),
        (99, 99, 99),
        100, 100, 100,
        func, 0.0
    )

    assert_allclose(vertices1, vertices2)
    assert_array_equal(triangles1, triangles2)


def test_no_duplicates():
    def sphere(x, y, z):
        return np.sqrt((x - 4)**2 + (y - 4)**2 + (z - 4)**2) - 4

    vertices, _ = mcubes.marching_cubes_func((2, 2, 2), (9, 9, 9), 20, 20, 20, sphere, 0)

    assert len(vertices) == len(np.unique(vertices, axis=0))


def test_export():

    u = np.zeros((10, 10, 10))
    u[2:-2, 2:-2, 2:-2] = 1.0
    vertices, triangles = mcubes.marching_cubes(u, 0.5)

    mcubes.export_obj(vertices, triangles, "output/test.obj")
    mcubes.export_off(vertices, triangles, "output/test.off")
    mcubes.export_mesh(vertices, triangles, "output/test.dae")


def test_invalid_input():

    def func(x, y, z):
        return x**2 + y**2 + z**2 - 1

    mcubes.marching_cubes_func((-1.5, -1.5, -1.5), (1.5, 1.5, 1.5), 10, 10, 10, func, 0)

    with pytest.raises(ValueError):
        mcubes.marching_cubes_func((0, 0, 0), (0, 0, 0), 10, 10, 10, func, 0)

    with pytest.raises(ValueError):
        mcubes.marching_cubes_func((-1.5, -1.5, -1.5), (1.5, 1.5, 1.5), 1, 10, 10, func, 0)

    with pytest.raises(Exception):
        mcubes.marching_cubes_func((-1.5, -1.5), (1.5, 1.5, 1.5), 10, 10, 10, func, 0)

    with pytest.raises(Exception):
        mcubes.marching_cubes_func((-1.5, -1.5, -1.5), (1.5, 1.5), 10, 10, 10, func, 0)