#graphics #bracket #cp437 #amethyst-support #roguelike #algorithm #rltk #traits #retrogaming


Traits required for the bracket-* crates. Adapt your maps to the traits with Algorithm2D, Algorithm3D and BaseMap.

6 releases

0.8.7 Oct 4, 2022
0.8.2 Feb 10, 2021
0.8.1 Apr 29, 2020
0.7.0 Feb 22, 2020
0.1.0 Feb 21, 2020

#138 in Game dev

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2,186 downloads per month
Used in 9 crates (2 directly)

MIT license



This crate provides traits for use in the bracket-pathfinding and bracket-geometry crates. It is part of the overall bracket-lib system.

Using a trait interface means that bracket-lib doesn't have to know or care about how you store your data, and can still provide useful geometry and path-finding functions. Defaults are provided, allowing you to get up and running quickly.

Everything is exported via bracket_algorithm_traits::prelude.

Map Indexing

A truly minimal implementation (replace TestMap with your map structure):

struct TestMap{};
impl BaseMap for TestMap {}
impl Algorithm2D for TestMap{
    fn dimensions(&self) -> Point {
        Point::new(2, 2)

This is sufficient to provide the following services:

  • in_bounds(Point): is a point within the dimensions of the map?
  • point2d_to_index(Point) -> usize: provides an array index for a point, within the map dimensions. It assumes that your array has striding by column.
  • index_to_point2d(usize) -> Point : provides an x/y coordinate for a given array index, assuming the same striding.

If you don't like the default implementations, feel free to override them.

There is an equivalent Algorithm3D for 3D grid-based maps (substitute Point3D for Point).

Map Traversal

The BaseMap trait helps you define the map. If you want to use path-finding, you need to implement the is_opaque function:

impl BaseMap for MyMap {
    fn is_opaque(&self, _idx: usize) -> bool {

To support path-finding, you need to implement two more functions:

impl BaseMap for MyMap {
    fn get_available_exits(&self, idx: usize) -> SmallVec<[(usize, f32); 10]> {
        // Provide a list of exit indices (you can use point2d_to_index to generate them) for this
        // tile inside the array.
        // Do NOT include the current tile as an available exit.

    fn get_pathing_distance(&self, _idx1: usize, _idx2: usize) -> f32 {
        // This should be a distance, using whatever heuristic you prefer.


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