# dcel
Dynamic doubly-connected edge list (DCEL) in Rust.
A [DCEL](https://en.wikipedia.org/wiki/Doubly_connected_edge_list) is a
topological data structure that represents a partition of a surface into easily
and quickly traversable vertices, edges, and faces, while making only minimal
assumptions about their shapes. You can freely choose wherever the vertices
should have two or more dimensions, or wheverer the edges are line segments or
curved arcs.
Mathematically, DCEL is an implementation of [ribbon
graph](https://ncatlab.org/nlab/show/ribbon+graph): a graph where every edge
is actually made of two half-edges directed in opposite (aka. darts) that are
also cyclically ordered around every vertex, making it possible to *rotate*
around a vertex by following one of them. This in turn also allows circulation
around faces (the regions formed by the arrangement of edges). Because of their
properties, these cyclic orderings are sometimes called *rotations*, together
forming a *rotation system*.
## Usage
### Adding dependency
First, add `dcel` as a dependency to your `Cargo.toml`
```toml
[dependencies]
dcel = "0.8"
```
## Documentation
See the [documentation](https://docs.rs/dcel/latest/dcel) for more information
about `dcel`'s usage.
## Packaging
`dcel` is published as a [crate](https://crates.io/crates/dcel) on the
[Crates.io](https://crates.io/) registry.
## Contributing
We welcome issues and pull requests from anyone to our canonical
[repository](https://codeberg.org/topola/dcel) on Codeberg.
## Licence
### Outbound licence
`dcel` is dual-licensed as under either of
- [MIT license](./LICENSES/MIT.txt),
- [Apache License, Version 2.0](./LICENSES/Apache-2.0.txt),
at your option.
### Inbound licence
Unless you expressly state otherwise, any contribution intentionally submitted
for inclusion in the work by you will be dual-licensed as described above,
without any additional terms or conditions.