https://github.com/pvigier/mygal
MyGAL is a computational geometry algorithms library
https://github.com/pvigier/mygal
delaunay-triangulation fortune-algorithm geometric-algorithms geometry geometry-library lloyd-relaxation voronoi voronoi-diagram
Last synced: about 1 year ago
JSON representation
MyGAL is a computational geometry algorithms library
- Host: GitHub
- URL: https://github.com/pvigier/mygal
- Owner: pvigier
- License: lgpl-3.0
- Created: 2018-11-21T20:46:18.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2022-11-21T15:45:55.000Z (over 3 years ago)
- Last Synced: 2025-05-13T01:07:59.828Z (about 1 year ago)
- Topics: delaunay-triangulation, fortune-algorithm, geometric-algorithms, geometry, geometry-library, lloyd-relaxation, voronoi, voronoi-diagram
- Language: C++
- Homepage: https://pvigier.github.io/docs/mygal/
- Size: 306 KB
- Stars: 39
- Watchers: 3
- Forks: 6
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# MyGAL
[](https://travis-ci.org/pvigier/MyGAL)
[](https://codecov.io/gh/pvigier/MyGAL)
MyGAL is a computational geometry algorithms library.
## Features
For the moment, the library is essentially based on [my implementation of Fortune's algorithm](https://github.com/pvigier/FortuneAlgorithm). It includes:
* [Voronoi diagram](https://en.wikipedia.org/wiki/Voronoi_diagram)
* [Lloyd's relaxation](https://en.wikipedia.org/wiki/Lloyd%27s_algorithm)
* [Delaunay triangulation](https://en.wikipedia.org/wiki/Delaunay_triangulation)
MyGAL is:
* easy to use
* easy to install (header-only and no external dependency)
* fast
* well documented
* multi-precision
## Getting started
To get started, you just have to add the `include` folder of MyGAL to the include directories of your project. Then, you just have to add this header to start using MyGAL:
```cpp
#include
```
To use the Fortune's algorithm to generate a Voronoi diagram, do the following:
```cpp
auto points = std::vector>{{0.354, 0.678}, {0.632, 0.189}, {0.842, 0.942}}; // Generate some points
auto algorithm = FortuneAlgorithm(points); // Initialize an instance of Fortune's algorithm
algorithm.construct(); // Construct the diagram
```
The template parameter corresponds to the floating point type used in computations. `double` is the recommended one.
The output diagram is unbounded but most of the time you will want a bounded one. To do that, we will compute the intersection between the diagram and a box. In MyGAL, we do that in two steps:
```cpp
algorithm.bound(Box{-0.05, -0.05, 1.05, 1.05}); // Bound the diagram
auto diagram = algorithm.getDiagram(); // Get the constructed diagram
diagram.intersect(Box{0.0, 0.0, 1.0, 1.0}); // Compute the intersection between the diagram and a box
```
Firstly, we bound the diagram then we compute the intersection. The two steps are due to technical details, you can read [this article](https://pvigier.github.io/2018/11/18/fortune-algorithm-details.html) if you want to know more. It is recommended to use a box slightly bigger for the bounded step than the one for the intersection step. Otherwise you might face numerical issues.
You can also obtain a Delaunay triangulation from the diagram:
```cpp
auto triangulation = diagram.computeTriangulation();
```
Or you can apply Lloyd's algorithm:
```cpp
auto relaxedPoints = diagram.computeLloydRelaxation()
```
## Example
If you want to build the example, you can use the cmake file present in the `example` folder. You will need [SFML](https://www.sfml-dev.org/).
The controls of the example are:
* `N`: to generate new random points
* `R`: to apply the Lloyd's algorithm
* `T`: to show the Delaunay triangulation
## Known issues
* If several points are aligned horizontally (exactly the same y-coordinate), the diagram may be incorrect.
* At least two points are expected.
* The algorithms are tuned to work with coordinates between 0 and 1. You may want to scale your data to obtain better results.
## Documentation
The documentation is available online [here](https://pvigier.github.io/docs/mygal/).
If you want to build the documentation, you have to have [Doxygen](http://www.doxygen.nl/) installed. Then you just have to execute the `doxygen` command in the `doc` folder.
To know more about the implementation you can read some [articles](https://pvigier.github.io/tag/geometry) on my blog.
## License
Distributed under the [GNU Lesser GENERAL PUBLIC LICENSE version 3](https://www.gnu.org/licenses/lgpl-3.0.en.html)
## Images
Voronoi diagram:
Delaunay triangulation:
Lloyd's relaxation:
