libigl - A simple c++ geometry processing library

http://igl.ethz.ch/projects/libigl/ https://github.com/alecjacobson/libigl/

Copyright 2014 - Alec Jacobson, Daniele Panozzo, Olga Diamanti, Kenshi Takayama, Leo Sacht, Wenzel Jacob, etc.

This is first and foremost a header library. Each header file should contain a single function. The function may have multiple prototypes. All functions should use the igl namespace and should adhere to the conventions and styles listed below.

New: As of 1 July 2014, we have released libigl as beta version 1.0. There are a number of changes we collected for this release to minimize confusion and changes to how you use libigl. See [Version 1.0 Changes][version1.0changes].

Installation

Libigl is a header library. You do not need to build anything to install. Simple add igl/ to your include path and include relevant headers. Here's a small "Hello, World" program:

#include <igl/cotmatrix.h>
#include <Eigen/Dense>
#include <Eigen/Sparse>
#include <iostream>
int main()
{
  Eigen::MatrixXd V(4,2);
  V<<0,0,
     1,0,
     1,1,
     0,1;
  Eigen::MatrixXi F(2,3);
  F<<0,1,2,
     0,2,3;
  Eigen::SparseMatrix<double> L;
  igl::cotmatrix(V,F,L);
  std::cout<<"Hello, mesh: "<<std::endl<<L*V<<std::endl;
  return 0;
}

If you save this in hello.cpp, then on gcc with Eigen installed via macports for example you could compile this with:

gcc -I/opt/local/include/eigen3 -I./igl/ hello.cpp -o hello

Running ./hello would then produce

Hello, mesh:
 0.5  0.5
-0.5  0.5
-0.5 -0.5
 0.5 -0.5

Tutorial

As of version 1.0, libigl includes an introductory tutorial that covers its basic functionalities. See tutorial/tutorial.md to get started.

Dependencies

• Eigen3 Last tested with Eigen Version 3.2

Optional

• OpenGL (disable with IGL_NO_OPENGL)
  • OpenGL >= 4 (enable with IGL_OPENGL_4)
• AntTweakBar (disable with IGL_NO_ANTTWEAKBAR) Last tested 1.16 (see libigl/external/AntTweakBar)
• GLEW Windows and Linux
• OpenMP
• libpng libiglpng extra only
• Mosek libiglmosek extra only
• Matlab libiglmatlab extra only
• boost libiglboost, libiglcgal extra only
• SSE/AVX libiglsvd3x3 extra only
• CGAL libiglcgal extra only
  • boost
  • gmp
  • mpfr
• CoMiSo libcomiso extra only

Optional (included in external/)

• TetGen libigltetgen extra only
• Embree libiglembree extra only
• tinyxml2 libiglxml extra only
• glfw libviewer extra only
• LIM liblim extra only

Header only

Libigl is designed to work "out-of-the-box" as a headers only library. To include libigl in your project. You need only include the libigl/include/ directory in your include path. To compile a hello-word example.cpp:

#include <Eigen/Dense>
#include <igl/readOBJ.h>
#include <iostream>
int main(int argc, char * argv[])
{
  if(argc>1)
  {
    Eigen::MatrixXd V;
    Eigen::MatrixXi F;
    igl::readOBJ(argv[1],V,F);
    std::cout<<"Hello, mesh with "<<V.rows()<<" vertices!"<<std::endl;
  }else{
    std::cout<<"Hello, world!"<<std::endl;
  }
  return 0;
}

using gcc (replacing appropriate paths):

g++ -I/usr/local/igl/libigl/include \
  -I/opt/local/include/eigen3 example.cpp -o example

Then run this example with:

./example examples/shared/TinyTorus.obj

Compilation as a static library

Libigl is developed most often on Mac OS X, though has current users in Linux and Windows.

Linux/Mac OS X/Cygwin

Libigl may also be compiled to a static library. This is advantageous when building a project with libigl, since when used as an header-only library can slow down compile times.

To build the entire libigl library producing lib/libigl.a, issue:

cd build
make lib

You may need to edit Makefile.conf accordingly. Best to give yourself an IGL_USERNAME and add a custom install suite for yourself. Then you can enable appropriate extras.

Extras

Once you've set up an IGL_USERNAME and enabled extras within Makefile.conf. You can build the extra libraries (into lib/ligiglpng.a, lib/libiglmatlab.a, lib/libigltetgen.a, lib/libiglmosek.a, etc.) by issuing:

cd build
make extras

Examples

You can make a slew of examples by issuing:

cd build
make examples

External

Finally there are a number of external libraries that we include in ./external/ because they are either difficult to obtain or they have been patched for easier use with libigl. Please see the respective readmes in those directories.

Installing AntTweakBar

To build the a static AntTweakBar library on Mac OS X issue:

cd external/AntTweakBar/src
make -f Makefile.osx.igl

Installing Tetgen

To build the tetgen library and executable on Mac OS X issue:

cd external/tetgen
make clean
rm -f obj/*.o
make -f Makefile.igl tetgen
rm -f obj/*.o
make -f Makefile.igl tetlib

Installing medit

To build the igl version of the medit executable on Mac OS X issue:

cd external/medit
make -C libmesh
make -f Makefile.igl medit

Installing Embree 2.0

To build the embree library and executables on Mac OS X issue:

cd external/embree
mkdir build
cd build
cmake ..
# Or using a different compiler
#cmake .. -DCMAKE_C_COMPILER=/opt/local/bin/gcc -DCMAKE_CXX_COMPILER=/opt/local/bin/g++
make
# Could also install embree to your root, but libigl examples don't expect
# this
#sudo make install

Installing tinyxml2

To build the a static tinyxml2 library on Mac OS X issue:

cd external/tinyxml2
cmake .
make

Installing YImg

To build the a static YImg library on Mac OS X issue:

cd external/yimg
make

You may need to install libpng. Systems with X11 might find this already installed at /usr/X11/lib.

Windows (Experimental)

To build a static library (.lib) on windows, open Visual Studio 2010.

• New > Project ...
• Visual C++ > Win32
• Win32 Console Application
• Name: libiglVisualStudio
• Uncheck "Create directory for solution"
• Then hit OK, and then Next
• Check "Static Library"
• Uncheck "Precompiled headers"
• Add all include/igl/*.cpp to the sources directory
• Add all include/igl/*.h to the headers directory
• Open Project > libigl Properties...
• Add the path to eigen3 to the include paths
• Change the target name to libigl
• Build and pray (this should create libigl.lib

Source

Examples

To get started, we advise that you take a look at a few examples:

./examples/hello-world/

./examples/meshio/

./examples/basic-topology/

./examples/ReAntTweakBar/

Extras

Libigl compartmentalizes dependences via its organization into a main libigl library and "extras."

bbw

This library extra contains functions for computing Bounded Biharmonic Weights, can be used with and without the mosek extra via the IGL_NO_MOSEK macro.

boost

This library extra utilizes the graph functions in the boost library for find connected components and performing breadth-first traversals.

cgal

This library extra utilizes CGAL's efficient and exact intersection and proximity queries.

embree

This library extra utilizes embree's efficient ray tracing queries.

matlab

This library extra provides support for reading and writing .mat workspace files, interfacing with Matlab at run time and compiling mex functions.

mosek

This library extra utilizes mosek's efficient interior-point solver for quadratic programs.

png

This library extra uses libpng and YImage to read and write .png files.

svd3x3

This library extra implements "as-rigid-as-possible" (ARAP) deformation techniques using the fast singular value decomposition routines written specifically for 3x3 matrices to use SSE intrinsics. This extra can still be compiled without sse support and support should be determined automatically at compile time via the __SSE__ macro.

tetgen

This library extra provides a simplified wrapper to the tetgen 3d tetrahedral meshing library.

viewer

This library extra utilizes glfw and glew to open an opengl context and launch a simple mesh viewer.

xml

This library extra utilizes tinyxml2 to read and write serialized classes containing Eigen matrices and other standard simple data-structures.

Development

Further documentation for developers is listed in tutorial.html, style_guidelines.html

License

See LICENSE.txt

Zipping

Zip this directory without .git litter and binaries using:

git archive -prefix=libigl/ -o libigl.zip master

Version 1.0 Changes

Our beta release marks our confidence that this library can be used outside of casual experimenting. To maintain order, we have made a few changes which current users should read and adapt their code accordingly.

Renamed functions

The following table lists functions which have changed name as of version 1.0.0:

Old	New
igl::add_barycenter	igl::false_barycentric_subdivision
igl::areamatrix	igl::vector_area_matrix
igl::barycentric2global	igl::barycentric_to_global
igl::boundary_faces	igl::boundary_facets
igl::boundary_vertices_sorted	igl::boundary_loop
igl::cotangent	igl::cotmatrix_entries
igl::edgetopology	igl::edge_topology
igl::gradMat	igl::grad
igl::is_manifold	igl::is_edge_manifold
igl::mexStream	igl::MexStream
igl::moveFV	igl::average_onto_vertices
igl::moveVF	igl::average_onto_faces
igl::plot_vector	igl::print_vector
igl::pos	igl::HalfEdgeIterator
igl::plane_project	igl::project_isometrically_to_plane
igl::project_points_mesh	igl::line_mesh_intersection
igl::read	igl::read_triangle_mesh
igl::removeDuplicates.cpp	igl::remove_duplicates
igl::removeUnreferenced	igl::remove_unreferenced
igl::tt	igl::triangle_triangle_adjacency
igl::vf	igl::vertex_triangle_adjacency
igl::write	igl::write_triangle_mesh
igl::manifold_patches	igl::orientable_patches
igl::selfintersect	igl::remesh_self_intersections
igl::project_mesh	igl::line_mesh_intersection
igl::triangulate	igl::polygon_mesh_to_triangle_mesh
igl::is_manifold	igl::is_edge_manifold
igl::triangle_wrapper	igl::triangulate

Miscellaneous

• To match interfaces provided by (all) other quadratic optimization libraries, igl::min_quad_with_fixed and igl::active_set now expect as input twice the quadratic coefficients matrix, i.e. the Hessian. For example, igl::min_quad_with_fixed(H,B,...) minimizes $\frac{1}{2}x^T H x+x^T B$.
• We have inverted the IGL_HEADER_ONLY macro to IGL_STATIC_LIBRARY. To compile using libigl as a header-only library, simply include headers and libigl in the header search path. To link to libigl, you must define the IGL_STATIC_LIBRARY macro at compile time and link to the libigl*.a libraries.
• Building libigl as a static library is now more organized. There is a build/ directory with Makefiles for the main library (Makefile) and each dependency (e.g. Makefile_mosek for libiglmosek.a)
• igl::polar_svd now always returns a rotation in R, never a reflection. This mirrors the behavior of igl::polar_svd3x3. Consequently the T part may have negative skews.
• We have organized the static
• The previous igl::grad function, which computed the per-triangle gradient of a per-vertex scalar function has been replaced. Now igl::grad computes the linear operator (previous computed using igl::gradMat). The gradient values can still be recovered by multiplying the operator against the scalar field as a vector and reshaping to have gradients per row.
• MASSMATRIX_* has become MASSMATRIX_TYPE_*
• The function igl::project_normals, which cast a line for each vertex of mesh A in the normal direction and found the closest intersection along these lines with mesh B, has been removed.

Contact

Libigl is a group endeavor led by Alec Jacobson and Daniele Panozzo. Please contact [email protected] if you have questions or comments. We are happy to get feedback! Enjoy!

If you're using libigl in your projects, quickly drop us a note. Tell us who you are and what you're using it for. This helps us apply for funding and justify spending time maintaining this.

If you find bugs or have problems please use our github issue tracking page.

Academic citation

If you use libigl in your research projects, please cite the papers we implement as appropriate. To cite the library in general, you could use this BibTeX entry:

@misc{libigl,
  title = {{libigl}: A simple {C++} geometry processing library},
  author = {Alec Jacobson and Daniele Panozzo and others},
  note = {http://igl.ethz.ch/projects/libigl/},
  year = {2013},
}