hexx

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, hexmod and offset coordinates.

See the hexagonal coordinate systems

Installation

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

• hexx = "0.18"

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 = "0.18", 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 = "0.18", features = ["packed"] }

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

• hexx = { version = "0.18", features = ["bevy_reflect"] }

hexx supports Face/Vertex/Edge grid handling using Hex as Face, GridVertex as vertex and GridEdge as edge. To enable it add the following line to your Cargo.toml:

• hexx = { version = "0.18", features = ["grid"] }

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_asset::RenderAssetUsages, render_resource::PrimitiveTopology,
     },
 };
 use hexx::MeshInfo;

 pub fn hexagonal_plane(mesh_info: MeshInfo) -> Mesh {
     Mesh::new(
         PrimitiveTopology::TriangleList,
         // Means you won't edit the mesh afterwards, check bevy docs for more information
         RenderAssetUsages::RENDER_WORLD,
     )
     .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_inserted_indices(Indices::U16(mesh_info.indices))
 }

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

See the examples for bevy usage

Q&A

Why not derive PartialOrd, Ord on Hex ?

Adding these traits to Hex would mean to define an absolute rule on how to solve this:

let a = hex(-10, 20);
let b = hex(1, 2);
a > b

Depending on how you consider this there are at least 3 possible rules:

• a.y is greater than b.y so it's true
• a.x is lower than b.x so it's false
• a's length is greater than b's so it's true

What if I want to use it in a BtreeMap, BTreeSet or BinaryHeap ?

Use a wrapper with the Ord and PartialOrd trait. You can copy and paste this code snippet into your project:

/// [`Ordering`] wrapper around [`Hex`], comparing [`Hex::y`] then [`Hex::x`].
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct OrdByYX(pub Hex);

impl Ord for OrdByYX {
    fn cmp(&self, other: &Self) -> Ordering {
        self.0.y.cmp(&other.0.y).then(self.0.x.cmp(&other.0.x))
    }
}

impl PartialOrd for OrdByYX {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

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

Hex Area

cargo run --example hex_area

This example showcases how to generate hexagonal areas using grid utilities and gizmos and how to use two layouts on the same grid.

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

Field of view

cargo run --example field_of_view

This example showcases the FOV algorithm, with an interactive range fov around your cursor. Clicking on tile toggles their visibility.

Field of movement

cargo run --example field_of_movement

This example showcases the field of movement algorithm, interactively displaying the accessible range of movement around the cursor.

3d columns

cargo run --example 3d_columns

This example showcases the 3d hexagon columns procedural generation

3d picking

cargo run --example 3d_picking

This example showcases how to use the camera ray to detect hovered 3d columns

Mesh builder

cargo run --example mesh_builder --features bevy_reflect

This example showcases the hexagon columns procedural generation customization options

Chunks

cargo run --example chunks

This example showcases the hexagon resolution system, allowing to tile coordinates in evenly sized chunks

Merged Chunks

cargo run --example merged_columns --features bevy_reflect

This example showcases how to build a simple hex chunk system with each chunk being a single mesh

Sprite Sheet

cargo run --example sprite_sheet

This example showcases how to use hexx with 2D sprite sheet.

Shapes

cargo run --example shapes --features bevy_reflect

This example showcases how to use hexx shapes module