Development in progress! API might change without further notice until first major release 1.x.x.
HexGrid library provides an easy and intuitive way of working with hexagonal grids. Under the hood it handles all the math so you can focus on more important stuff.
- Support for grids of any shape, including irregular shapes, or grids with holes in them.
The library is meant for generic backend use. Therefore it doesn't perform any UI or rendering. However, it provides the calculations that will be needed for rendering.
- Create or generate a grid of hexagonal cells.
- Various coordinate systems (cube, axial, offset), and conversion between them.
- Rotation, Manhattan distance, linear interpolation.
- Get Neighbors or diagonal neighbors.
- Get Line (get all hexes making a line from A to B).
- Get Ring (get all hexes making a ring from an origin coordinates in specified radius).
- Get Filled Ring (get all hexes making a filled ring from an origin coordinates in specified radius).
- Find reachable hexes within
nsteps (Breath First Search).
- Find the shortest path from A to B (optimized A* search algorithm).
- FieldOfView algorithm (
ShadowCastingdesigned for hexagonal grids).
- Hexagon rendering related functions (e.g. get polygon corners).
- Code inline documentation (quick help).
- Solid unit tests coverage.
- Automated documentation generator (SwiftDoc + GitHub Actions -> hosted on repo GitHub Pages).
- Demo with visualization.
What's coming next?
- We are done for the moment. Any feature requests or ideas are welcome.
HexGrid in action
HexGrid demo app using SpriteKit. (Also available in the App Store.) HexGrid demo app using SwiftUI.
Integrating HexGrid to your project
Add HexGrid as a dependency to your
import PackageDescription let package = Package( name: "MyApp", dependencies: [ ... // Add HexGrid package here .package(url: "https://github.com/fananek/hex-grid.git", from: "0.4.11") ], ... targets: [ .target(name: "App", dependencies: [ .product(name: "HexGrid", package: "hex-grid"), ...
Import HexGrid package to your code.
import HexGrid ... // your code goes here
Creating a grid
Grids can be initialized either with a set of cell coordinates, or HexGrid can generate some standard shaped grids for you.
Standard shape grids
... // create grid of hexagonal shape var grid = HexGrid(shape: GridShape.hexagon(10)) // or rectangular shape var grid = HexGrid(shape: GridShape.rectangle(8, 12)) // or triangular shape var grid = HexGrid(shape: GridShape.triangle(6))
See the section on
GridShape below for more details, and a full list of the available grid shapes.
... // create new HexGrid let gridCells: Set<Cell> = try [ Cell(CubeCoordinates(x: 2, y: -2, z: 0)), Cell(CubeCoordinates(x: 0, y: -1, z: 1)), Cell(CubeCoordinates(x: -1, y: 1, z: 0)), Cell(CubeCoordinates(x: 0, y: 2, z: -2)) ] var grid = HexGrid(cells: gridCells) ...
Initializers and drawing
Note that, assuming you want to draw your grid, you'll want to think about whether to pass a size for each cell (
hexSize) or a size for the entire Grid (
pixelSize) to the initializer. (See "Drawing the Grid" below.)
HexGrid <-> JSON
HexGrid conforms to swift
Codable protocol so it can be easily encoded to or decoded from JSON.
// encode (grid to JSON) let grid = HexGrid(shape: GridShape.hexagon(5) ) let encoder = JSONEncoder() let data = try encoder.encode(grid)
// decode (JSON to grid) let decoder = JSONDecoder() let grid = try decoder.decode(HexGrid.self, from: data)
Grid operations examples
Almost all functions have two variants. One that works with
Cell and the other one works with
CubeCoordinates. Use those which better fulfill your needs.
Get Cell at coordinates
let cell = grid.cellAt(try CubeCoordinates(x: 1, y: 0, z: -1))
Check whether a coordinate is valid (meaning it has a corresponding
Cell in the grid's
// returns Bool isValidCoordinates(try CubeCoordinates(x: 2, y: 4, z: -6))
Get blocked or non blocked Cells
let blockedCells = grid.blockedCells() // or let nonBlockedCells = grid.nonBlockedCells()
Get single neighbor
// get neighbor for a specific Cell let neighbor = try grid.neighbor( for: someCell, at: Direction.Pointy.northEast.rawValue) // get just neighbor coordinates let neighborCoordinates = try grid.neighborCoordinates( for: someCoordinates, at: Direction.Pointy.northEast.rawValue)
Get all neighbors
// get all neighbors for a specific Cell let neighbors = try grid.neighbors(for: someCell) // get only coordinates of all neighbors let neighborsCoords = try grid.neighbors(for: someCoordinates)
Get line from A to B
// returns nil in case line doesn't exist let line = try grid.line(from: originCell, to: targetCell)
// returns all cells making a ring from origin cell in radius let ring = try grid.ring(from: originCell, in: 2)
Get filled ring
// returns all cells making a filled ring from origin cell in radius let ring = try grid.filledRing(from: originCell, in: 2)
Find reachable cells
// find all reachable cells (max. 4 steps away from origin) let reachableCells = try grid.findReachable(from: origin, in: 4)
Find shortest path
// returns nil in case path doesn't exist at all let path = try grid.findPath(from: originCell, to: targetCell)
Calculate field of view (FOV)
Cell has an attribute called
isOpaque. Its value can be
false. Based on this information it's possible to calculate so called field of view. It means all cells visible from specific position on grid, considering all opaque obstacles.
// set cell as opaque obstacleCell.isOpaque = true
In order to get field of view, simply call following function.
// find all hexes visible in radius 4 from origin cell let visibleHexes = try grid.fieldOfView(from: originCell, in: 4)
By default cell is considered visible as soon as its center is visible from the origin cell. If you want to include partially visible cells as well, use optional paramter
// find all hexes even partially visible in radius 4 from origin cell let visibleHexesIncludingPartials = try grid.fieldOfView(from: originCell, in: 4, includePartiallyVisible: true)
Drawing the Grid
HexGrid calculates all "pixel coordinates" using one of two methods:
- Using a size for each
Cell(stored in the
- Using a size for the entire Grid (stored in the
Note that both the
pixelSizeproperties are stored internally as
HexSizestructures. Try not to get confused by this!
HexSizeis just a convenient way to store
Which flavor of
HexGrid initializer you want to use will depend on which of these methods best applies to your use case. When specifying the
pixelSize is calculated for you, and when specifying the
hexSize is likewise set automatically.
While it is not possible to modify the
pixelSize properties directly (after initialization), you can set the grid's
pixelSize (and re-calculate
hexSize from it) at any time using the
fitGrid(in size: HexSize) function. Note that this also resets the
The origin property
You can think of the
origin property as the center point of the
Note that you can specify the
originat initialization, but only when using the
cellSizemethod. When specifying
pixelSize, the origin is set for you, so the grid "fits" inside the specified width & height.
It will be important to change the
origin property any time you want to change the pixel coordinates for your Grid. Changing the
origin will modify the return values of all pixel-calculating functions. You can use this to apply an offset for your grid, or "re-center" it later.
Corner Pixel Coordinates
Usually, when drawing hexagons, you will want the screen coordinates of the polygon corners for each
let corners = grid.polygonCorners(for: someCell)
Center Pixel Coordinates
This function returns a
Point struct (x: and y: values) for the center of a
let screenCoords = grid.pixelCoordinates(for: someCell)
Finding a Cell at screen coordinates
// return cell for specified screen coordinates (or nil if such cell doesn't exists) let cell = try grid.cellAt(point)
For detailed information see complete documentation
Data structures you should know
Represents the grid itself as well as it's an entry point of the HexGrid library.
HexGrid is defined by set of
Cells and few other properties. All together makes a grid setup. In other words it put grid cells into a meaningful context. Therefore most of available operations are being called directly on a grid instance because it make sense only with such context (grid setup).
Set<Cell>- grid cells
Orientation- see Orientation enumeration
OffsetLayout- see OffsetLayout enumeration
HexSize- width and height of a hexagon
Point- 'display coordinates' (x, y) of a grid origin
HexSize- pixel width and height of the entire grid
[String: Attribute]- dictionary of custom attributes (most primitive types are supported as well as nesting)
Cell is a building block of a grid.
CubeCoordinates- cell placement on a grid coordinate system
[String: Attribute]- dictionary of custom attributes (most primitive types are supported as well as nesting)
Bool- used by algorithms (reachableCells, pathfinding etc.)
Bool- used by fieldOfView algorithm
Float- used by pathfinding algorithm. For the sake of simplicity let's put graph theory aside. You can imagine cost as an amount of energy needed to pass a cell. Pathfinding algorithm then search for path requiring the less effort.
The most common coordinates used within HexGrid library is cube coordinate system. This type of coordinates has three axis x, y and z. The only condition is that sum of its all values has to be equal zero.
// valid cube coordinates CubeCoordinates(x: 1, y: 0, z: -1) -> sum = 0 // invalid cube coordinates CubeCoordinates(x: 1, y: 1, z: -1) -> sum = 1 -> throws error
For more details check Amit Patel's explanation.
OffsetLayout is used primarily for rectangular shaped grids. It has two options but their meaning can differ based on grid orientation.
There are four offset types depending on orientation of hexagons. The “row” types are used with with pointy top hexagons and the “column” types are used with flat top.
- Pointy on top orientation
- odd-row (slide alternate rows right)
- even-row (slide alternate rows left)
- Flat on top orientation
- odd-column (slide alternate columns up)
- even-column (slide alternate columns down)
Cases from this enumeration can be passed into the
HexGrid constructor to generate grids of various shapes and sizes.
rectangle(Int, Int)- Associated values are column width and row height of the generated grid. Sides of the grid will be essentially parallel to the edges of the screen.
parallelogram(Int, Int)- Associated values are both side-lengths.
hexagon(Int)- This generates a regular hexagon shaped grid, with all sides the length of the associated value.
elongatedHexagon(Int, Int)- This is used to generate a grid shaped like a regular hexagon that has been stretched or elongated in one dimension. The associated values are side lengths.
irregularHexagon(Int, Int)- This is used to generate a grid shaped like a hexagon where every other side is the length of the two associated values.
triangle(Int)- Generates an equilateral triangle with all sides the length of the associated value.
Direction enumeration is consistent and human recognizable direction naming. Using direction enumeration is not only much more convenient but it also help to avoid errors. It's better to say just "Hey, I'm on cell X and want to go north." than think "What the hack was that index of north direction?", isn't it?
There is actually separate set of directions for each grid orientation. It's because of two reasons. First, some directions are valid only for one or another orientation. Second, direction raw values are shifted based on orientation.
See also the list of contributors who participated in this project.
All code contained in the HexGrid package is under the MIT license agreement.