| ## IGL copyleft subdirectory | |
| Functions in the `include/igl/copyleft/` subdirectory are in the | |
| `igl::copyleft::` namespace to indicate that they are under a more aggressive | |
| [copyleft](https://en.wikipedia.org/wiki/Copyleft) than | |
| [MPL2](https://en.wikipedia.org/wiki/Mozilla_Public_License) used for the main | |
| `include/igl` directory and `igl::` namespace. Most notably, this subdirectory | |
| includes code that is under | |
| [GPL](https://en.wikipedia.org/wiki/GNU_General_Public_License). | |
| Typically a company planning on developing software without releasing its | |
| source code will avoid or purchase licenses for such dependencies. If you do | |
| obtain such a license for the dependencies employed here, you are free to use | |
| the libigl functions here as per their MPL2 license. | |