PrusaSlicer-NonPlainar/tests/libslic3r/test_indexed_triangle_set.cpp

#include <iostream>
#include <fstream>
#include <catch2/catch.hpp>

#include "libslic3r/TriangleMesh.hpp"

using namespace Slic3r;

TEST_CASE("Split empty mesh", "[its_split][its]") {
    using namespace Slic3r;

    indexed_triangle_set its;

    std::vector<indexed_triangle_set> res = its_split(its);

    REQUIRE(res.empty());
}

TEST_CASE("Split simple mesh consisting of one part", "[its_split][its]") {
    using namespace Slic3r;

    auto cube = its_make_cube(10., 10., 10.);

    std::vector<indexed_triangle_set> res = its_split(cube);

    REQUIRE(res.size() == 1);
    REQUIRE(res.front().indices.size() == cube.indices.size());
    REQUIRE(res.front().vertices.size() == cube.vertices.size());
}

void debug_write_obj(const std::vector<indexed_triangle_set> &res, const std::string &name)
{
#ifndef NDEBUG
    size_t part_idx = 0;
    for (auto &part_its : res) {
        its_write_obj(part_its, (name + std::to_string(part_idx++) + ".obj").c_str());
    }
#endif
}

TEST_CASE("Split two non-watertight mesh", "[its_split][its]") {
    using namespace Slic3r;

    auto cube1 = its_make_cube(10., 10., 10.);
    cube1.indices.pop_back();
    auto cube2 = cube1;

    its_transform(cube1, identity3f().translate(Vec3f{-5.f, 0.f, 0.f}));
    its_transform(cube2, identity3f().translate(Vec3f{5.f, 0.f, 0.f}));

    its_merge(cube1, cube2);

    std::vector<indexed_triangle_set> res = its_split(cube1);

    REQUIRE(res.size() == 2);
    REQUIRE(res[0].indices.size() == res[1].indices.size());
    REQUIRE(res[0].indices.size() == cube2.indices.size());
    REQUIRE(res[0].vertices.size() == res[1].vertices.size());
    REQUIRE(res[0].vertices.size() == cube2.vertices.size());

    debug_write_obj(res, "parts_non_watertight");
}

TEST_CASE("Split non-manifold mesh", "[its_split][its]") {
    using namespace Slic3r;

    auto cube = its_make_cube(10., 10., 10.), cube_low = cube;

    its_transform(cube_low, identity3f().translate(Vec3f{10.f, 10.f, 10.f}));
    its_merge(cube, cube_low);
    its_merge_vertices(cube);

    std::vector<indexed_triangle_set> res = its_split(cube);

    REQUIRE(res.size() == 2);
    REQUIRE(res[0].indices.size() == res[1].indices.size());
    REQUIRE(res[0].indices.size() == cube_low.indices.size());
    REQUIRE(res[0].vertices.size() == res[1].vertices.size());
    REQUIRE(res[0].vertices.size() == cube_low.vertices.size());

    debug_write_obj(res, "cubes_non_manifold");
}

TEST_CASE("Split two watertight meshes", "[its_split][its]") {
    using namespace Slic3r;

    auto sphere1 = its_make_sphere(10., 2 * PI / 200.), sphere2 = sphere1;

    its_transform(sphere1, identity3f().translate(Vec3f{-5.f, 0.f, 0.f}));
    its_transform(sphere2, identity3f().translate(Vec3f{5.f, 0.f, 0.f}));

    its_merge(sphere1, sphere2);

    std::vector<indexed_triangle_set> res = its_split(sphere1);

    REQUIRE(res.size() == 2);
    REQUIRE(res[0].indices.size() == res[1].indices.size());
    REQUIRE(res[0].indices.size() == sphere2.indices.size());
    REQUIRE(res[0].vertices.size() == res[1].vertices.size());
    REQUIRE(res[0].vertices.size() == sphere2.vertices.size());

    debug_write_obj(res, "parts_watertight");
}

#include <libslic3r/QuadricEdgeCollapse.hpp>
TEST_CASE("Reduce one edge by Quadric Edge Collapse", "[its]")
{
    indexed_triangle_set its;
    its.vertices = {Vec3f(-1.f, 0.f, 0.f), Vec3f(0.f, 1.f, 0.f),
                    Vec3f(1.f, 0.f, 0.f), Vec3f(0.f, 0.f, 1.f),
                    // vertex to be removed
                    Vec3f(0.9f, .1f, -.1f)};
    its.indices  = {Vec3i(1, 0, 3), Vec3i(2, 1, 3), Vec3i(0, 2, 3),
                   Vec3i(0, 1, 4), Vec3i(1, 2, 4), Vec3i(2, 0, 4)};
    // edge to remove is between vertices 2 and 4 on trinagles 4 and 5

    indexed_triangle_set its_ = its; // copy
    // its_write_obj(its, "tetrhedron_in.obj");
    size_t wanted_count = its.indices.size() - 1;
    CHECK(its_quadric_edge_collapse(its, wanted_count));
    // its_write_obj(its, "tetrhedron_out.obj");
    CHECK(its.indices.size() == 4);
    CHECK(its.vertices.size() == 4);

    for (size_t i = 0; i < 3; i++) { 
        CHECK(its.indices[i] == its_.indices[i]);
    }

    for (size_t i = 0; i < 4; i++) {
        if (i == 2) continue;
        CHECK(its.vertices[i] == its_.vertices[i]);
    }

    const Vec3f &v = its.vertices[2]; // new vertex
    const Vec3f &v2 = its_.vertices[2]; // moved vertex
    const Vec3f &v4 = its_.vertices[4]; // removed vertex
    for (size_t i = 0; i < 3; i++) { 
        bool is_between = (v[i] < v4[i] && v[i] > v2[i]) ||
                          (v[i] > v4[i] && v[i] < v2[i]);
        CHECK(is_between);
    }
}

#include "test_utils.hpp"
TEST_CASE("Symplify mesh by Quadric edge collapse to 5%", "[its]")
{
    TriangleMesh mesh = load_model("frog_legs.obj");
    double original_volume = its_volume(mesh.its);
    size_t wanted_count = mesh.its.indices.size() * 0.05;
    REQUIRE_FALSE(mesh.empty());
    indexed_triangle_set its = mesh.its; // copy
    its_quadric_edge_collapse(its, wanted_count);
    // its_write_obj(its, "frog_legs_qec.obj");
    CHECK(its.indices.size() <= wanted_count);
    double volume = its_volume(its);
    CHECK(fabs(original_volume - volume) < 30.);
}