libigl/libigl#1656 hot-fix

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🌱 Linking to prebuilt libigl libraries 🌱

Suppose you have a new project that will use libigl. You could compile it in header only mode (IGL_STATIC_LIBRARY not defined), but every compilation of your project will be slow. Or you could compile it in static library mode by adding libigl as a subproject your projects cmake (include(libigl.cmake)). However, the first compile of your project will take a very long time. This also scales badly. If you have n libigl projects, you'll end up compiling n copies of libigl.

This project demonstrates how to link against prebuilt libigl static libraries. The intended use case is for rapid prototyping many small libigl projects (each within their own cmake environment) on a machine with a common libigl build directory. The FindLIBIGL.cmake defined here is compatible with the standard libigl setup and controlled by the option LIBIGL_USE_PREBUILT_LIBRARIES).

Example setup:

Assume that you've downloaded and compiled libigl somewhere else. For example, maybe you ran:

git clone https://github.com/libigl/libigl.git
cd libigl
mkdir build
cd build
cmake ../ -DLIBIGL_USE_STATIC_LIBRARY=ON -DLIBIGL_WITH_CGAL=ON -DLIBIGL_WITH_MATLAB=ON -DLIBIGL_WITH_MOSEK=ON
make -j8

This make will take quite a while, but once it's done, the libigl/build/ director will contain static libraries:

libigl/build/libCoMISo.a
libigl/build/libglad.a
libigl/build/libglfw3.a
libigl/build/libigl.a
libigl/build/libigl_cgal.a
libigl/build/libigl_comiso.a
libigl/build/libigl_embree.a
libigl/build/libigl_matlab.a
libigl/build/libigl_mosek.a
libigl/build/libigl_opengl.a
libigl/build/libigl_opengl_glfw.a
libigl/build/libigl_opengl_glfw_imgui.a
libigl/build/libigl_png.a
libigl/build/libigl_predicates.a
libigl/build/libigl_stb_image.a
libigl/build/libigl_tetgen.a
libigl/build/libigl_triangle.a
libigl/build/libigl_xml.a
libigl/build/libimgui.a
libigl/build/libimguizmo.a
libigl/build/libpredicates.a
libigl/build/libtetgen.a
libigl/build/libtinyxml2.a
libigl/build/libtriangle.a

Now, consider another project somewhere else. For example,

git clone https://alecjacobson/libigl-link-example
cd libigl-link-example
mkdir build
cd build
# replace ../../libigl with path to your libigl directory above
cmake ../ -DLIBIGL_DIR=../../libigl/ -DLIBIGL_USE_PREBUILT_LIBRARIES=ON
make -j8

This will simply compile your project and link to the externally located libigl libraries (and – if all goes well – all necessary dependency libraries).

🐞 Debuggin'

It may be useful to build a second copy of libigl in debug mode. For example, you might do:

cd libigl
mkdir debug
cd debug
cmake ../ -DCMAKE_BUILD_TYPE=DEBUG -DLIBIGL_USE_STATIC_LIBRARY=ON -DLIBIGL_WITH_CGAL=ON -DLIBIGL_WITH_MATLAB=ON -DLIBIGL_WITH_MOSEK=ON
make -j8

If you similar build your project in debug mode, then you can tell cmake to use the debug version of libigl:

cd libigl-link
mkdir debug
cd debug
# replace ../../libigl with path to your libigl directory above
cmake ../ -DLIBIGL_DIR=../../libigl/  -DLIBIGL_BUILD_DIR=../../libigl/debug -DCMAKE_BUILD_TYPE=DEBUG -DLIBIGL_USE_PREBUILT_LIBRARIES=ON
make -j8