Implement high level algorithms

Hexagonal tools lib in rust.

Inspired by this RedBlobGames article and Sander Evers work

This lib allows you to:

Manipulate hexagon coordinates
Generate hexagonal maps with custom layouts and orientation
Generate hexagon meshes (planes or columns)

I made the choice to use Axial Coordinates for performance and utility reasons, but the [Hex] type has conversion utilities with cubic, doubled and offset coordinates.

See the hexagonal coordinate systems

Installation

Minimum supported rust version (MSRV) is 1.72.1

Run cargo add hexx in your project or add the following line to your Cargo.toml:

hexx = "0.14"

Cargo features

hexx supports serialization and deserialization of most types using serde, through the serde feature gate. To enable it add the following line to your Cargo.toml:

hexx = { version = "0.14", features = ["serde"] }

By default Hex uses rust classic memory layout, if you want to use hexx through the FFI or have Hex be stored without any memory padding, the packed feature will make Hex repr(C). To enable this behaviour add the following line to your Cargo.toml:

hexx = { version = "0.14", features = ["packed"] }

hexx supports Bevy Reflection through the bevy_reflect feature. To enable it add the following line to your Cargo.toml:

hexx = { version = "0.14", features = ["bevy_reflect"] }

Features

hexx provides the [Hex] coordinates with:

Distances
Neighbors and directions
Lines
Ranges
Rings
Edges
Wedges
Spirals
Rotation
Symmetry
Vector operations
Conversions to other coordinate systems:
- Cubic coordinates
- Offset coordinates
- Doubled coordinates
- Hexmod coordinates
Multiple hex resolution

Basic usage

 use hexx::*;

 // Declare points in hexagonal spaces
 let point_a = hex(10, -5); // Equivalent of `Hex::new(10, -5)`
 let point_b = hex(-8, 15);
 // Find distance between them
 let dist = point_a.unsigned_distance_to(point_b);
 // Compute a line between points
 let line: Vec<Hex> = point_a.line_to(point_b).collect();
 // Compute a ring from `point_a` containing `point_b`
 let ring: Vec<Hex> = point_a.ring(dist).collect();
 // Rotate `point_b` around `point_a` by 2 times 60 degrees clockwise
 let rotated = point_b.rotate_cw_around(point_a, 2);
 // Find the direction between the two points
 let dir_a = point_a.main_direction_to(point_b);
 let dir_b = point_b.main_direction_to(point_a);
 assert!(dir_a == -dir_b);
 // Compute a wedge from `point_a` to `point_b`
 let wedge = point_a.wedge_to(point_b);
 // Get the average value of the wedge
 let avg = wedge.average();

Layout usage

[HexLayout] is the bridge between your world/screen/pixel coordinate system and the hexagonal coordinates system.

 use hexx::*;

 // Define your layout
 let layout = HexLayout {
     hex_size: Vec2::new(1.0, 1.0),
     orientation: HexOrientation::Flat,
     ..Default::default()
 };
 // Get the hex coordinate at the world position `world_pos`.
 let world_pos = Vec2::new(53.52, 189.28);
 let point = layout.world_pos_to_hex(world_pos);
 // Get the world position of `point`
 let point = hex(123, 45);
 let world_pos = layout.hex_to_world_pos(point);

Wrapping

[HexBounds] defines a bounding hexagon around a center coordinate. It can be used for boundary and interesection checks but also for wrapping coordinates. Coordinate wrapping transform a point outside of the bounds to a point inside. This allows for seamless or repeating wraparound maps.

use hexx::*;

let center = hex(23, -45);
let radius = 5;
let bounds = HexBounds::new(center, radius);
let outside_coord = hex(12345, 98765);
assert!(!bounds.is_in_bounds(outside_coord));
let wrapped_coord = bounds.wrap(outside_coord);
assert!(bounds.is_in_bounds(wrapped_coord));

Resolutions and chunks

[Hex] support multi-resolution coordinates. In practice this means that you may convert a coordinate to a different resolution:

To a lower resolution, meaning retrieving a parent coordinate
to a higher resolution, meaning retrieving the center child coordinate

Resolutions are abstract, the only useful information is the resolution radius.

For example, if you use a big grid, with a radius of a 100, you might want to split that grid evenly in larger hexagons containing a 10 radius of coordinates and maybe do operations locally inside of these chunks.

So instead of using a big range directly:

use hexx::*;

const MAP_RADIUS: u32 = 100;

// Our big grid with hundreds of hexagons
let big_grid = Hex::ZERO.range(MAP_RADIUS);

You may define a smaller grid you will then divide to a higher resolution

use hexx::*;

const CHUNK_RADIUS: u32 = 10;
const MAP_RADIUS: u32 = 20;

let chunks = Hex::ZERO.range(MAP_RADIUS);
for chunk in chunks {
    // We can retrieve the center of that chunk by increasing the resolution
    let center = chunk.to_higher_res(CHUNK_RADIUS);
    // And retrieve the other coordinates in the chunk
    let children = center.range(CHUNK_RADIUS);
    // We can retrieve the chunk coordinates from any coordinate..
    for coord in children {
        // .. by reducing the resolution
        assert_eq!(coord.to_lower_res(CHUNK_RADIUS), chunk);
    }
}

An other usage could be to draw an infinite hex grid, with different resolutions displayed, dynamically changing according to user zoom level.

Usage in Bevy

If you want to generate 3D hexagonal mesh and use it in bevy you may do it this way:

 use bevy::{
     prelude::Mesh,
     render::{mesh::Indices, render_resource::PrimitiveTopology},
 };
 use hexx::MeshInfo;

 pub fn hexagonal_plane(mesh_info: MeshInfo) -> Mesh {
     Mesh::new(PrimitiveTopology::TriangleList)
         .with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, mesh_info.vertices)
         .with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, mesh_info.normals)
         .with_inserted_attribute(Mesh::ATTRIBUTE_UV_0, mesh_info.uvs)
         .with_indices(Some(Indices::U16(mesh_info.indices)))
 }

The [MeshInfo] can be produced from [PlaneMeshBuilder] or [ColumnMeshBuilder]

See the examples for bevy usage

Examples

hexx provides interactive examples showcasing various features:

Hex grid

cargo run --example hex_grid

This example showcases hex ranges, rings, wedges, rotation, and lines

Scroll Map

cargo run --example scroll_map

This example showcases the HexMap struct for scrolling maps

Wrap Map

cargo run --example wrap_map

This example showcases the HexMap struct for looping/wrapping map

A Star pathfinding

cargo run --example a_star

This example showcases the A star algorithm, with an interactive pathfinding between the origin and your cursor. Clicking on tile toggles their availability