AMCAXMeshing Algorithm Samples

1. Overview

This tutorial provides the basic usage of using AMCAXMeshing for triangle mesh algorithm.

1.1 Trianlge Soup

AMCAXMeshing uses triangle soup to store mesh data. Triangle soup mainly contains the coordinates of mesh points and the index information of faces, and is a template parameter that mesh algorithms rely on.

class TriSoupTraits_Coord
{
public:
    using PointT    = VecProxy<3, double>;
    using VecT      = VecProxy<3, double>;
    using NormalT   = VecProxy<3, double>;
    using Tex3D     = VecProxy<3, double>;
    using Color     = VecProxy<3, float>;
    using Triangle  = VecProxy<3, int>;
    using Points    = std::vector<PointT>;
    using Normals   = std::vector<NormalT>;
    using Tex3Ds    = std::vector<Tex3D>;
    using Colors    = std::vector<Color>;
    using Triangles = std::vector<Triangle>;
};

1.2 Using namespace

For clarity in the example code, using namespace

using namespace AMCAX;
using namespace Meshing;

1.3 Mesh IO

AMCAXMeshing currently provides reading and writing of commonly used mesh file formats such as obj and stl.

mesh IO header file

#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"

write "example_utils.h" to set input and output paths

#pragma once
 
#include <filesystem>
#include <fstream>
#include <stack>
#include <string>
#include <vector>
 
inline bool make_file_writable(const std::string &filename)
{
    std::filesystem::path filepath(filename);
 
    if (std::filesystem::exists(filepath) && std::filesystem::is_regular_file(filepath))
        return true;
 
    std::filesystem::path parent_path = filepath.parent_path();
    if (std::filesystem::exists(parent_path) && std::filesystem::is_directory(parent_path))
        return true;
 
    std::filesystem::create_directories(parent_path);
 
    return false;
}
 
inline bool make_dir_writable(const std::string &dirname)
{
    std::filesystem::path dirpath(dirname);
 
    if (std::filesystem::exists(dirpath) && std::filesystem::is_directory(dirpath))
        return true;
 
    std::filesystem::create_directories(dirpath);
 
    return false;
}
 
#define OUTPUT_DIRECTORY(TEST_SUIT_NAME, TEST_NAME)           \
    std::string outdir =                                        \
      "./data/test_output/" #TEST_SUIT_NAME "/" #TEST_NAME "/"; \
    make_dir_writable(outdir)

2. Algorithm Examples

2.1 Mesh Simplify

#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"
#include "meshModeling/TriSoup_FastQEM.hpp"
 
#include "example_utils.h"
 
#include <cfloat>
#include <thread>
 
using namespace AMCAX::Meshing;
using namespace AMCAX::Meshing::Mesh;
using namespace AMCAX::Meshing::Remeshing;
 
void Remeshing_FastQEM()
{
    OUTPUT_DIRECTORY(Remeshing, FastQEM);
 
    bool first = true;
    int  stage, current, total;
 
    FastQEM<TriSoupTraits_Coord>::ProFn pro_fn =
      [&first, &stage, &current, &total](int _stage, int _current, int _total,
                                         AMCAXMeshing_UNUSED bool &cancel) -> void
    {
        stage   = _stage;
        current = _current;
        total   = _total;
 
        if (!first)
            std::cout << "\r\033[K";
 
        std::cout << "stage: " << _stage << "/"
                  << FastQEM<TriSoupTraits_Coord>::Total << ", process: " << current
                  << "/" << total;
        first = false;
        // set cancel to true if you want to terminate the algorithm :)
        if (stage == FastQEM<TriSoupTraits_Coord>::Stage::Total)
            std::cout << std::endl;
    };
 
    IOOptions io_options;
    io_options.vertex_has_point = true;
 
    OBJReader<TriSoupTraits_Coord> obj_reader;
    OBJWriter<TriSoupTraits_Coord> obj_writer;
 
    std::string filename = "32770_sf";
 
    obj_reader.read("./data/" + filename + ".obj", io_options);
    for (double ratio : {0.01, 0.1, 0.3, 0.6})
    {
        first = true;
        FastQEM<TriSoupTraits_Coord> fast_qem(obj_reader.m_points,
                                              obj_reader.m_triangles);
 
        Logger::elapse_reset();
 
        std::thread simplify_thread(
          [&]()
          {
              fast_qem.simplify(size_t(obj_reader.m_triangles.size() * ratio),
                                0.1f, 20, pro_fn);
          });
 
        simplify_thread.join();
 
        auto elapsed = Logger::elapsed();
        Logger::info("FastQEM: ratio " + std::to_string(ratio) + ";  time " +
                     std::to_string(elapsed.count()) + " s");
 
        obj_writer.clear();
        obj_writer.m_points    = std::move(fast_qem.m_points);
        obj_writer.m_triangles = std::move(fast_qem.m_triangles);
        std::string out_filename =
          outdir + filename + "_FastQEM_" + std::to_string(ratio) + ".obj";
        obj_writer.write(out_filename, io_options, 10);
    }
}

Click here example1 to get the complete source code for the above example, which you can download according to your learning needs.

2.2 Mesh Boolean

#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"
#include "mesh/io/STLReader.hpp"
#include "mesh/io/STLWriter.hpp"
#include "meshModeling/MeshBoolean.hpp"
#include "meshModeling/TriMeshRepair.hpp"
 
#include "example_utils.h"
 
// geometry kernel, hidden for users, just use it. :D
using EIAC          = AMCAX::Meshing::Geometry::EIAC;
// Triangle soup traits defined by Common
using TriSoupTraits = AMCAX::Meshing::Mesh::TriSoupTraits_Coord;
 
// points and triangles from traits
using Points    = typename TriSoupTraits::Points;
using Triangles = typename TriSoupTraits::Triangles;
 
// Define reader and writer
using OBJReader = AMCAX::Meshing::Mesh::OBJReader<TriSoupTraits>;
using OBJWriter = AMCAX::Meshing::Mesh::OBJWriter<TriSoupTraits>;
using STLReader = AMCAX::Meshing::Mesh::STLReader<TriSoupTraits>;
using STLWriter = AMCAX::Meshing::Mesh::STLWriter<TriSoupTraits>;
using IOOptions  = AMCAX::Meshing::Mesh::IOOptions;
 
// Define boolean
using MeshBoolean = AMCAX::Meshing::Boolean::MeshBoolean<EIAC, TriSoupTraits>;
 
void read_mesh(const std::string &filename, Points &points,
               Triangles &triangles, IOOptions &io_options
               )
{
    if (AMCAX::Meshing::ends_with(filename, ".obj"))
    {
        OBJReader reader;
        reader.read(filename, io_options);
        
        points    = std::move(reader.m_points);
        triangles = std::move(reader.m_triangles);
    }
    else if (AMCAX::Meshing::ends_with(filename, ".stl"))
    {
        STLReader reader;
        reader.read(filename, io_options);
        
        points    = std::move(reader.m_points);
        triangles = std::move(reader.m_triangles);
    }
}
 
void write_mesh(const std::string &filename, const Points &points,
                const Triangles &triangles, IOOptions &io_options)
{
    OBJWriter writer;
    writer.m_points    = std::move(points);
    writer.m_triangles = std::move(triangles);
    writer.write(filename, io_options, 10);
};
 
void MeshBoolean_MeshBoolean()
{
    OUTPUT_DIRECTORY(Boolean, Boolean);
 
    // Define IO
    IOOptions io_options;
    io_options.vertex_has_point = true;
 
    Points    points1, points2, result_points;
    Triangles triangles1, triangles2, result_triangles;
 
    // read mesh
    read_mesh("./data/boolean_data/bunny25k.obj", points1, triangles1, io_options);
    read_mesh("./data/boolean_data/cow.obj", points2, triangles2, io_options);
 
    MeshBoolean boolean(true);
    // set input meshes
    boolean.addTriMeshAsInput(points1, triangles1);
    boolean.addTriMeshAsInput(points2, triangles2);
    // set output mesh
    boolean.setTriMeshAsOutput(result_points, result_triangles);
 
    // run arrangements and labeling.
    // the results will be temporarily cached, until be cleared or destroyed.
    boolean.computeLabels();
 
    // after arrangements and labeling done, we can
    // apply differenct boolean operations faster.
    // (NOTE: must call computeLabels before boolean operation)
    {
        boolean.Union();
        make_file_writable(outdir + "AMCAXMeshing_Union.obj");
        write_mesh(outdir + "AMCAXMeshing_Union.obj", result_points,
                   result_triangles, io_options);
    }
 
    {
        boolean.Intersection();
        make_file_writable(outdir + "AMCAXMeshing_Intersection.obj");
        write_mesh(outdir + "AMCAXMeshing_Intersection.obj", result_points,
                   result_triangles, io_options);
    }
 
    {
        boolean.Xor();
        make_file_writable(outdir + "AMCAXMeshing_Xor.obj");
        write_mesh(outdir + "AMCAXMeshing_Xor.obj", result_points, result_triangles,
                   io_options);
    }
 
    {
        boolean.Subtraction();
        make_file_writable(outdir + "AMCAXMeshing_Subtraction.obj");
        write_mesh(outdir + "AMCAXMeshing_Subtraction.obj", result_points,
                   result_triangles, io_options);
    }
}

Click here example2 to get the complete source code for the above example, which you can download according to your learning needs.

2.3 Mesh Repair

#include "meshModeling/MeshArrangements.hpp"
#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"
#include "mesh/io/STLReader.hpp"
#include "mesh/io/STLWriter.hpp"
#include "meshModeling/TriMeshRepair.hpp"
 
#include "example_utils.h"
 
 
 
using namespace AMCAX::Meshing;
using namespace AMCAX::Meshing::Mesh;
using namespace AMCAX::Meshing::MeshTools;
 
void MeshRepair_MeshRepair()
{
    OUTPUT_DIRECTORY(MeshRepair, MeshRepair);
    bool first = true;
    int  stage;
    AMCAX::Meshing::MeshTools::TriMeshRepair<TriSoupTraits_Coord>::ProFn pro_fn =
      [&first, &stage](int _stage, AMCAXMeshing_UNUSED bool &cancel) -> void
    {
        stage = _stage;
 
        if (!first)
            std::cout << "\r\033[K";
 
        std::cout
          << "stage: " << _stage << "/"
          << AMCAX::Meshing::MeshTools::TriMeshRepair<TriSoupTraits_Coord>::Total;
        first = false;
 
        // set cancel to true if you want to terminate the algorithm :)
        if (stage == AMCAX::Meshing::MeshTools::TriMeshRepair<
                       TriSoupTraits_Coord>::Stage::Total)
            std::cout << std::endl;
    };
 
    IOOptions io_options;
    io_options.vertex_has_point = true;
    io_options.face_has_normal  = true;
 
    OBJReader<TriSoupTraits_Coord> obj_reader;
    STLReader<TriSoupTraits_Coord> stl_reader;
    OBJWriter<TriSoupTraits_Coord> obj_writer;
    STLWriter<TriSoupTraits_Coord> stl_writer;
 
    std::string                    modelname = "CamelBox";
    TriSoupTraits_Coord::Points    result_points;
    TriSoupTraits_Coord::Triangles result_triangles;
 
    stl_reader.read("./data/repair_data/" + modelname + ".stl", io_options);
    TriMeshRepair<TriSoupTraits_Coord> repair(stl_reader.m_points,
                                              stl_reader.m_triangles);
 
    repair.repair(true, pro_fn);
 
    stl_writer.m_points    = repair.m_points;
    stl_writer.m_triangles = repair.m_triangles;
 
    make_file_writable(outdir + modelname + "_repaired.stl");
    io_options.stl_binary = true;
    stl_writer.write(outdir + modelname + "_repaired.stl", io_options, 10);
 
    obj_writer.m_points    = repair.m_points;
    obj_writer.m_triangles = repair.m_triangles;
 
    make_file_writable(outdir + modelname + "_repaired.obj");
    obj_writer.write(outdir + modelname + "_repaired.obj", io_options, 10);
}

Click here example3 to get the complete source code for the above example, which you can download according to your learning needs.

2.4 Mesh Subdivision

2.4.1 ButterFly Subdivision

#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"
#include "meshModeling/TriSoup_FastQEM.hpp"
#include "meshModeling/TriSoup_ButterFlySubdivision.hpp"
 
#include "example_utils.h"
 
#include <cfloat>
 
using namespace AMCAX::Meshing;
using namespace AMCAX::Meshing::Mesh;
using namespace AMCAX::Meshing::Subdivision;
using namespace AMCAX::Meshing::Remeshing;
 
void Subdivision_TriSoup_ButterFly()
{
    OUTPUT_DIRECTORY(Subdivision, TriSoup_ButterFly);
 
    IOOptions io_options;
    io_options.vertex_has_point = true;
 
    OBJReader<TriSoupTraits_Coord> obj_reader;
    OBJWriter<TriSoupTraits_Coord> obj_writer;
    std::string                    filename = "kelan";
 
    obj_reader.read("./data/subdivision_data/" + filename + ".obj", io_options);
 
    for (double ratio : {2., 3., 4., 5., 6., 7., 8., 9., 10., 11., 12.})
    {
        TriSoup_ButterFlySubdivision<TriSoupTraits_Coord, true> subdivider(
          obj_reader.m_points, obj_reader.m_triangles);
 
        Logger::elapse_reset();
 
        size_t sub_times = size_t(std::ceil(ratio / 4.0) + 0.1);
 
        for (size_t i = 0; i < sub_times; i++)
            subdivider.subdivide();
 
        FastQEM<TriSoupTraits_Coord> fast_qem(std::move(subdivider.m_points),
                                              std::move(subdivider.m_triangles));
 
        if (size_t(obj_reader.m_triangles.size() * ratio +
                   fast_qem.m_triangles.size() * 0.01) <
            fast_qem.m_triangles.size())
            fast_qem.simplify(size_t(obj_reader.m_triangles.size() * ratio), FLT_MAX,
                              20);
 
        auto elapsed = Logger::elapsed();
 
        Logger::info("ButterFly: ratio " + std::to_string(ratio) + ";  time " +
                     std::to_string(elapsed.count()) + " s");
 
        obj_writer.clear();
        obj_writer.m_points    = std::move(fast_qem.m_points);
        obj_writer.m_triangles = std::move(fast_qem.m_triangles);
 
        std::string out_filename = outdir + filename +
                                   "_TriSoupModifiedButterFly_" +
                                   std::to_string(ratio) + ".obj";
        make_file_writable(out_filename);
        obj_writer.write(out_filename, io_options, 10);
    }
}

Click here example4 to get the complete source code for the above example, which you can download according to your learning needs.

2.4.2 Loop Subdivision

#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"
#include "meshModeling/TriSoup_FastQEM.hpp"
#include "meshModeling/TriSoup_LoopSubdivision.hpp"
 
#include "example_utils.h"
 
#include <cfloat>
 
using namespace AMCAX::Meshing;
using namespace AMCAX::Meshing::Mesh;
using namespace AMCAX::Meshing::Remeshing;
using namespace AMCAX::Meshing::Subdivision;
 
void Subdivision_TriSoup_LoopSubdivision()
{
    OUTPUT_DIRECTORY(Subdivision, TriSoup_LoopSubdivision);
 
    IOOptions io_options;
    io_options.vertex_has_point = true;
 
    OBJReader<TriSoupTraits_Coord> obj_reader;
    OBJWriter<TriSoupTraits_Coord> obj_writer;
    std::string                    filename = "kelan";
 
    obj_reader.read("./data/subdivision_data/" + filename + ".obj", io_options);
 
    for (double ratio : {2., 3., 4., 5., 6., 7., 8., 9., 10., 11., 12.})
    {
        TriSoup_LoopSubdivision<TriSoupTraits_Coord> subdivider(
          obj_reader.m_points, obj_reader.m_triangles);
 
        Logger::elapse_reset();
 
        size_t sub_times = size_t(std::ceil(ratio / 4.0) + 0.1);
 
        for (size_t i = 0; i < sub_times; i++)
            subdivider.subdivide();
 
        FastQEM<TriSoupTraits_Coord> fast_qem(std::move(subdivider.m_points),
                                              std::move(subdivider.m_triangles));
 
        if (size_t(obj_reader.m_triangles.size() * ratio +
                   fast_qem.m_triangles.size() * 0.01) <
            fast_qem.m_triangles.size())
            fast_qem.simplify(size_t(obj_reader.m_triangles.size() * ratio), FLT_MAX,
                              12);
 
        auto elapsed = Logger::elapsed();
 
        Logger::info("Loop: ratio " + std::to_string(ratio) + ";  time " +
                     std::to_string(elapsed.count()) + " s");
 
        obj_writer.clear();
        obj_writer.m_points    = std::move(fast_qem.m_points);
        obj_writer.m_triangles = std::move(fast_qem.m_triangles);
 
        std::string out_filename =
          outdir + filename + "_TriSoupLoopSub_" + std::to_string(ratio) + ".obj";
        make_file_writable(out_filename);
        obj_writer.write(out_filename, io_options, 10);
    }
}

Click here example5 to get the complete source code for the above example, which you can download according to your learning needs.

2.5 Remeshing

2.5.1 Incremental Remeshing

#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"
#include "meshModeling/TriMesh_IncrementalRemeshing.hpp"
#include "example_utils.h"
 
using namespace AMCAX::Meshing;
using namespace AMCAX::Meshing::Mesh;
using namespace AMCAX::Meshing::Remeshing;
 
void Remeshing_Incremental()
{
    IOOptions io_options;
    io_options.vertex_has_point = true;
 
    OBJReader<TriSoupTraits>      obj_reader;
    OBJWriter<TriSoupTraits>      obj_writer;
    TriMesh_IncrementalRemeshing<TriSoupTraits> inc_remesher;
    std::string                   filename = "32770_sf";
 
    obj_reader.read("./data/" + filename + ".obj", io_options);
    obj_writer.clear();
    inc_remesher.setReferenceMesh(obj_reader.m_points, obj_reader.m_triangles);
    inc_remesher.setVariableMesh(obj_writer.m_points, obj_writer.m_triangles);
 
    TriMesh_IncrementalRemeshing<TriSoupTraits>::Params param;
    param.targetEdgeLength = 0.005;
    param.isAdaptive = false;
    
    inc_remesher.remesh(param);
    std::string out_filename = filename + "_Incremental_.obj";
    obj_writer.write(out_filename, io_options, 10); 
}

Click here example6 to get the complete source code for the above example, which you can download according to your learning needs.

2.6 Mesh parameterisation algorithm

// mesh IO header
#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"
// mesh parameterization header
#include "meshModeling/MeshParameterization.hpp"
// some utils functions
#include "example_utils.h"
 
using namespace AMCAX::Meshing;
using namespace AMCAX::Meshing::Mesh;
using namespace AMCAX::Meshing::Parameterization;
 
void Parameterization_Bijective()
{
    // make directory for output file path
    OUTPUT_DIRECTORY(Parameterization, Bijective);
 
    IOOptions io_options;
    io_options.vertex_has_point = true;
 
    OBJReader<TriSoupTraits> obj_reader;
    OBJWriter<TriSoupTraits> obj_writer;
    // read mesh
    obj_reader.read("./data/parameterization_data/cow.obj", io_options);
    // define parameterization object
    AMCAX::Meshing::Parameterization::BijectivePara<TriSoupTraits> para(
      obj_reader.m_points, obj_reader.m_triangles, obj_writer.m_points);
    // execute algorithm
    para.parameterization();
    // write mesh
    obj_writer.m_triangles   = std::move(obj_reader.m_triangles);
    std::string out_filename = outdir + "res_parameterization.obj";
    obj_writer.write(out_filename, io_options, 10);
}

2.7 Mesh Cutting Algorithm

#include "mesh/io/OBJReader.hpp"
#include "mesh/io/OBJWriter.hpp"
 
#include "meshModeling/MeshParameterization.hpp"
#include "meshModeling/TriMeshCut.hpp"
 
#include "example_utils.h"
 
using namespace AMCAX::Meshing;
using namespace AMCAX::Meshing::Mesh;
using namespace AMCAX::Meshing::Parameterization;
 
// Define points and triangles from traits
using Points    = typename TriSoupTraits::Points;
using Triangles = typename TriSoupTraits::Triangles;
 
// Function for parameterization with mesh cut
void Parameterization_With_MeshCut()
{
    OUTPUT_DIRECTORY(Parameterization, Bijective_With_MeshCut);
 
    IOOptions io_options;
    io_options.vertex_has_point = true;
 
    OBJReader<TriSoupTraits> obj_reader;
    OBJWriter<TriSoupTraits> obj_writer;
 
    std::string in_filename       = "./data/boolean_data/bunny25k.obj";
    std::string out_cut_filename  = outdir + "bunny_cut.obj";
    std::string out_para_filename = outdir + "bunny_parameterization.obj";
 
    // Read the object file
    obj_reader.read(in_filename, io_options);
 
    Points    i_points    = std::move(obj_reader.m_points);
    Triangles i_triangles = std::move(obj_reader.m_triangles);
 
    // Perform mesh cut
    AMCAX::Meshing::TriMeshCut::GreedyCut<TriSoupTraits> mesh_cut(
      i_points, i_triangles, /*verbose*/ true);
 
    Points    cut_points;
    Triangles cut_triangles;
 
    mesh_cut.cut(cut_points, cut_triangles);
 
    // Write the cut mesh to a new file
    obj_writer.m_points    = cut_points;
    obj_writer.m_triangles = cut_triangles;
    obj_writer.write(out_cut_filename, io_options, 10);
    obj_writer.clear();
 
    Points para_points;
 
    // Perform bijective parameterization on the cut mesh
    AMCAX::Meshing::Parameterization::BijectivePara<TriSoupTraits> para(
      cut_points, cut_triangles, para_points, /*verbose*/ true);
    para.parameterization();
 
    // Write the parameterized cut mesh to a new file
    obj_writer.m_points    = std::move(para_points);
    obj_writer.m_triangles = std::move(cut_triangles);
    obj_writer.write(out_para_filename, io_options, 10);
}