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https://github.com/virtualritz/polyhedron-ops

Conway-Hart Polyhedron Notation in Rust
https://github.com/virtualritz/polyhedron-ops

3delight bevy geometry nsi polygon-mesh polyhedra polyhedron rust

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Conway-Hart Polyhedron Notation in Rust

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README 

        
# Polyhedron Operators



This crate implements the [Conway Polyhedron

Operators](http://en.wikipedia.org/wiki/Conway_polyhedron_notation)

and their extensions by [George W. Hart](http://www.georgehart.com/)

and others.



![Some brutalist Polyhedron, rendered with 3Delight|ɴsɪ](polyhedron.jpg)



*Some brutalist polyhedron; rendered with

[3Delight|ɴsɪ](https://www.3delight.com) and post processed in

[Ansel](https://ansel.photos/).*



This is an experiment to improve my understanding of iterators in Rust.

It is based on [Kit Wallace](http://kitwallace.tumblr.com/tagged/conway)’s

OpenSCAD code. As OpenSCAD Language is functional it lends itself well to

translation into functional Rust.



```rust

use polyhedron_ops::Polyhedron;

use std::path::Path;



// Conway notation: gapcD

let polyhedron =

    Polyhedron::dodecahedron()  // D

        .chamfer(None, true)    // c

        .propellor(None, true)  // p

        .ambo(None, true)       // a

        .gyro(None, None, true) // g

        .finalize();



// Export as ./polyhedron-gapcD.obj

polyhedron.write_obj(&Path::new("."), false);

```



The above code starts from a

[dodecahedron](https://en.wikipedia.org/wiki/Dodecahedron) and

iteratively applies four operators.



The resulting shape is shown below.



![A polyhedron](gapcD.jpg)



## Caveat



This is in a semi-polised shape. Documentation could be better (open an issue

if you feel something is particualrly lacking).



In short: use at your own risk.



## Cargo Features



* `bevy` – Adds support for converting a polyhedron into a

  [`bevy`](https://bevyengine.org/)

  [`Mesh`](https://docs.rs/bevy/latest/bevy/render/mesh/struct.Mesh.html).



* `nsi`  – Adds support for sending a polyhedron to an offline renderer

  via the [ɴsɪ](https://crates.io/crates/nsi/) crate.



* `obj`  – Adds support for writing data out as

  [Wavefront OBJ](https://en.wikipedia.org/wiki/Wavefront_.obj_file).



* `parser` – Add support for parsing strings in

  [Conway Polyhedron Notation](https://en.wikipedia.org/wiki/Conway_polyhedron_notation).

  This feature implements `Polyhedron::TryFrom<&str>`.



## Base Shapes



* [x] Platonic solids

* [x] Prisms

* [x] Antiprisms

* [ ] Pyramids

* [ ] Johnson Solids



## Supported Operators



* [x] **a** – ambo

* [x] **b** – bevel (equiv. to **ta**)

* [x] **c** – chamfer

* [x] **d** – dual

* [x] **e** – expand (a.k.a. explode, equiv. to **aa**)

* [x] **g** – gyro

* [x] **i** – inset/loft (equiv. to **x,N**)

* [x] **j** – join (equiv. to **dad**)

* [x] **K** – Quick & dirty canonicalization

* [x] **k** – kis

* [x] **M** – medial (equiv. to **dta**)

* [x] **m** – meta (equiv. to **k,,3j**)

* [x] **n** – needle (equiv. to **dt**)

* [x] **o** – ortho (equiv. to **jj**)

* [x] **p** – propellor

* [x] **q** – quinto

* [x] **r** – reflect

* [x] **S** – spherize

* [x] **s** – snub (equiv. to **dgd**)

* [x] **t** – truncate (equiv. to **dkd**)

* [x] **v** – subdivide (Catmull-Clark)

* [x] **w** – whirl

* [x] **x** – extrude

* [x] **z** – zip (equiv. to **dk**)



### Other Operators



* [ ] **H** – hollow (called ‘intrude’ in Wings3D)

* [ ] **h** – hexpropellor

* [ ] **l** – stellate

* [ ] **?** – triangulate



## Playing



There is a playground example app to test things & have fun:



```text

cargo run --release --example playground --features obj

```



If you want to produce images like the ones above you need to

[download the free version of the 3Delight renderer](https://www.3delight.com/download)

and install that. After that, run the example with

[ɴsɪ](https://crates.io/crates/nsi/) support:



```text

cargo run --release --example playground --features nsi,obj

```



### Keyboard Commands



Use keys matching the operator name from the above list to apply.



Use `Up` and `Down` to adjust the parameter of the the last operator.

Combine with `Shift` for 10× the change.



`Delete` undoes the last (and only the last) operation.



Press `F1` to render with 3Delight (requires a [3Delight|ɴsɪ

installation](https://www.3delight.com/download)).

Combine with `Shift` to render with 3Delight Cloud (requires registration).



Press `Space` to save as `$HOME/polyhedron-.obj`.



Export & render will always yield a correct OBJ though. Which you can

view in Wings, Blender or another DCC app.



## Contributors



[donbright](https://github.com/donbright)