subsphere

Sphere tessellation toolkit

This crate provides a general, easy-to-use API for working with tessellated spheres, i.e. spheres whose surface is partitioned into polygonal cells. It includes implementations for a variety of such tessellations.

Features

• Implicit Representation: Instead of storing geometry data directly, the tessellations, and the elements within them, are represented implicitly. They are compact zero-allocation Copy types that can be used to generate geometry on the fly. This lets you work with massive tessellations using very little memory.

• Versatility: This crate allows you to explore a huge variety of tessellations, all sharing a common API. There's a bunch of adjustable parameters and you're free to mix-and-match topologies and projections to tune the tessellation to your needs.

• Spherical Geometry: In the world of subsphere, there is only one geometric space: the sphere. All objects follow the contours of the sphere, and all calculations correctly account for this.

Examples

Construct a tessellation by refining a base tessellation

let sphere = subsphere::icosphere()
    .subdivide_edge(NonZero::new(3).unwrap())
    .with_projector(subsphere::proj::Fuller)
    .truncate();

Construct a tessellation explicitly

let sphere = subsphere::HexSphere::from_kis(
    subsphere::TriSphere::new(
        subsphere::BaseTriSphere::Icosa,
        subsphere::proj::Fuller,
        NonZero::new(9).unwrap(),
        0,
    )
).unwrap();

Write a tessellation to an OBJ file

let mut obj = String::new();
for vert in sphere.vertices() {
    let pos = vert.pos();
    obj.push_str(&format!("v {} {} {}\n", pos[0], pos[1], pos[2]));
}
for face in sphere.faces() {
    let indices = face
        .vertices()
        .map(|vert| format!("{}", vert.index() + 1)) // OBJ indices are 1-based
        .collect::<Vec<_>>();
    obj.push_str(&format!("f {}\n", indices.join(" ")));
}
std::fs::write("sphere.obj", &obj).expect("failed to write to file");

Toggle neighboring faces when a face is clicked

// Setup
let mut is_active = vec![false; sphere.num_faces()];

// For each click
let click_face = sphere.face_at(click_point);
for side in click_face.sides() {
    let neighbor_index = side.twin().inside().index();
    is_active[neighbor_index] = !is_active[neighbor_index];
}