# 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](https://www.3delight.com) and post processed in
[Darktable](https://www.darktable.org/).*
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_to_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.
## 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-<type>.obj`.
I use `kiss3d` for realtime preview which, [for now](https://github.com/sebcrozet/kiss3d/issues/263),
limits meshes to 64k vertices. This means the preview will be broken/missing bits
once your mesh hits this limit.
Export & render will always yield a correct OBJ though. Which you can
view in Wings, Blender or another DCC app.
