To compile a normal binary you can use (as per the instructions in the igl documentation)
note: this assumes libigl is in a sibling directory
g++ -std=c++11 -I/usr/local/include/eigen3 -I../libigl/include/ hello.cpp -o hello
But, to compile an Emscripten version, use:
em++ -std=c++11 -I/usr/local/include/eigen3 -I../libigl/include/ hello.cpp -o hello
To build the web version use:
em++ -std=c++11 -I/usr/local/include/eigen3 -I../libigl/include/ hello.cpp -o index.html
Run:
emcc -I ../libigl/include -I/usr/local/include/eigen3 --bind -o hello_binding.js hello_binding_example.cpp
to generate a new hello_binding.js file, which you can see the results of if you serve & open hello_binding_example.html