Octahedron

Add the octahedron module

src/lib.rs additions:

#![allow(unused)]
fn main() {
use truck_meshalgo::prelude::*;

// ...keep earlier functions: write_polygon_mesh, triangle, square, tetrahedron, hexahedron...
pub mod octahedron; // add this
pub use octahedron::octahedron; // add this
}

Construct Main Function

src/octahedron.rs:

#![allow(unused)]
fn main() {
use std::iter::FromIterator;
use truck_meshalgo::prelude::*;

/// Octahedron with vertices on the coordinate axes.
pub fn octahedron() -> PolygonMesh {

    //PLACE STEP 1-4 HERE

}
}

Step 1: Define vertex positions

#![allow(unused)]
fn main() {
    let positions = vec![
        Point3::new(-1.0, 0.0, 0.0), // (-X) [0]
        Point3::new(1.0, 0.0, 0.0),  // (+X) [1]
        Point3::new(0.0, -1.0, 0.0), // (-Y) [2]
        Point3::new(0.0, 1.0, 0.0),  // (+Y) [3]
        Point3::new(0.0, 0.0, -1.0), // (-Z) [4]
        Point3::new(0.0, 0.0, 1.0),  // (+Z) [5]
    ];
}

Step 2: Build attribute set

#![allow(unused)]
fn main() {
    let attrs = StandardAttributes {
        positions,
        ..Default::default()
    };
}

Step 3: Define mesh faces

#![allow(unused)]
fn main() {
    let faces = Faces::from_iter([
        [0, 4, 2],
        [2, 4, 1],
        [1, 4, 3],
        [3, 4, 0],
        [0, 2, 5],
        [2, 1, 5],
        [1, 3, 5],
        [3, 0, 5],
    ]);
}

Step 4: Construct the mesh

#![allow(unused)]
fn main() {
    PolygonMesh::new(attrs, faces)
}

Export the octahedron

Add examples/octahedron.rs:

fn main() {
    let mesh = truck_meshes::octahedron();
    truck_meshes::write_polygon_mesh(&mesh, "output/octahedron.obj");
}

Run it:

cargo run --example octahedron

View it

Open output/octahedron.obj in your preferred OBJ file viewer. You should see a single octahedron.

gif below from Bambu Studio.

Octahedron

Note that Bambu Studio (forked from PrusaSlicer) only supports triangular meshes at the moment.

File tree after this step

truck_meshes/
├─ Cargo.toml
├─ src/
│  ├─ lib.rs
│  ├─ triangle.rs
│  ├─ square.rs
│  ├─ tetrahedron.rs
│  ├─ hexahedron.rs
│  └─ octahedron.rs
├─ examples/
│  ├─ triangle.rs
│  ├─ square.rs
│  ├─ tetrahedron.rs
│  ├─ hexahedron.rs
│  └─ octahedron.rs
└─ output/          # exported OBJ files (e.g., output/octahedron.obj)

Full code:

src/lib.rs:

#![allow(unused)]
fn main() {
use truck_meshalgo::prelude::*;

/// Write any mesh to an OBJ file.
pub fn write_polygon_mesh(mesh: &PolygonMesh, path: &str) {
    let mut obj = std::fs::File::create(path).unwrap();
    obj::write(mesh, &mut obj).unwrap();
}

pub mod triangle;
pub use triangle::triangle;

pub mod square;
pub use square::square;

pub mod tetrahedron;
pub use tetrahedron::tetrahedron;

pub mod hexahedron;
pub use hexahedron::hexahedron;

pub mod octahedron;
pub use octahedron::octahedron;
}

src/octahedron.rs:

#![allow(unused)]
fn main() {
use std::iter::FromIterator;
use truck_meshalgo::prelude::*;

pub fn octahedron() -> PolygonMesh {
    let positions = vec![
        Point3::new(-1.0, 0.0, 0.0),
        Point3::new(1.0, 0.0, 0.0),
        Point3::new(0.0, -1.0, 0.0),
        Point3::new(0.0, 1.0, 0.0),
        Point3::new(0.0, 0.0, -1.0),
        Point3::new(0.0, 0.0, 1.0),
    ];

    let attrs = StandardAttributes {
        positions,
        ..Default::default()
    };

    let faces = Faces::from_iter([
        [0, 4, 2],
        [2, 4, 1],
        [1, 4, 3],
        [3, 4, 0],
        [0, 2, 5],
        [2, 1, 5],
        [1, 3, 5],
        [3, 0, 5],
    ]);

    PolygonMesh::new(attrs, faces)
}
}

examples/octahedron.rs:

fn main() {
    let mesh = truck_meshes::octahedron();
    truck_meshes::write_polygon_mesh(&mesh, "output/octahedron.obj");
}

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