Hexagon grid library which is GUI agnostic. Supports a multitude of grid layouts including hexagonal, triangular, rectangular and more.
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README.md

Hexameter

Hexameter is a hexagonal grid library. The motivation behind it is to have an optimized, simple and usable library for drawing hexagonal grids without being tied to any GUI framework. It is 100% unit tested (apart from some generated code).

This means that you can use Hexameter on Android, your backend or your desktop app. There is a REST-based web example which you can tinker with here. You can also check out more code examples in the hexameter-examples project here.

Hexameter currently supports a maximum grid size of 1000 * 1000 (1.000.000 cells) with the default implementation but you can provide your own storage implementation to allieviate this limitation.

Note that this library uses RxJava. You should familiarize yourself with the basics (nothing more needed) in order to use it effectively. If you don't want to learn RxJava don't worry the code examples below can be used without diving into the details.

Getting started

This library uses Amit's guide to hexagonal grids. The coordinate system used by this library is the Cubic coordinate system. Please check here for further details.

Hexagonal grids come in flat topped and pointy topped shapes. The grid can have several layouts:

  • Hexagonal: the width and height of a this layout has to be equal and both have to be an odd number.
  • Triangular: the width and height of a this layout has to be equal.
  • Rectangular: no special rules
  • Trapezoid: no special rules

All layouts have with and height values of at least 1. You can consult HexagonalGridLayout if you need further details.

This library is not tied to any GUI implementation. All operations provided by the API are working using the most abstract concept possible.

Basic usage

Maven dependency

Let's start by adding Hexameter as a Maven dependency to your project:

<dependency>
    <groupId>org.codetome</groupId>
    <artifactId>hexameter-core</artifactId>
    <version>3.0.0</version>
</dependency>

You can also use Gradle:

'org.codetome:hexameter-core:3.0.0'

Creating a grid

You can use the HexagonalGridBuilder from the API package to create a HexagonalGrid:

import org.codetome.hexameter.core.api.HexagonalGridLayout;
import org.codetome.hexameter.core.api.HexagonOrientation;
import org.codetome.hexameter.core.api.HexagonalGrid;
import org.codetome.hexameter.core.api.HexagonalGridBuilder;

import static org.codetome.hexameter.core.api.HexagonalGridLayout.RECTANGULAR;
import static org.codetome.hexameter.core.api.HexagonOrientation.FLAT_TOP;
// ...
private static final int GRID_HEIGHT = 9;
private static final int GRID_WIDTH = 9;
private static final HexagonalGridLayout GRID_LAYOUT = RECTANGULAR;
private static final HexagonOrientation ORIENTATION = FLAT_TOP;
private static final double RADIUS = 30;

// ...
HexagonalGriBuilder builder = new HexagonalGridBuilder()
    .setGridHeight(GRID_HEIGHT)
    .setGridWidth(GRID_WIDTH)
    .setGridLayout(GRID_LAYOUT)
    .setOrientation(ORIENTATION)
    .setRadius(RADIUS);

HexagonalGrid grid = builder.build();

You can also use the HexagonalGridBuilder to create a HexagonalGridCalculator for you which supports advanced operations on HexagonalGrids:

import org.codetome.hexameter.core.api.HexagonalGridCalculator;
// ...
HexagonalGridCalculator calculator = builder.buildCalculatorFor(grid);

Drawing a grid

You can fetch the Hexagons stored on a grid using the getHexagons method:

Observable<Hexagon> hexagons = grid.getHexagons();

After that you can iterate over all the Points of your Hexagons:

hexagons.forEach(new Action1<Hexagon>() {
    @Override
    public void call(Hexagon hexagon) {
        for (Point point : hexagon.getPoints()) {
            // do what you want
        }
    }
});

Note that each Point represents a coordinate in 2D space. You can use them for drawing.

Manipulating your grid

There are basically only one operation for manipulating your data on the grid: The Hexagon#setSatelliteData(T data) operation with which you can add your own arbitrary data to a Hexagon object. This means that once created a HexagonalGrid is immutable apart from the satellite data you add.

There is also a HexagonalGrid#clearSatelliteData() method for clearing all satellite data from your grid.

The implementation of the HexagonalGrid is lazy. This means that it only stores data which is absolutely necessary to keep in memory (the coordinates and your satellite data). Everything else is generated on the fly. The only limiting factor of a grid at the moment is the coordinates (which consume memory) and the satellite data.

GUI example:

You can find a simple GUI example in the hexameter-swt-example submodule. Run it by doing the following steps.

  1. Clone the project: git clone git@github.com:adam-arold/hexameter.git
  2. cd to the newly created hexameter folder: cd hexameter/
  3. build the project: mvn clean install
  4. run the created uberjar: java -jar hexameter-examples/hexameter-swt-example/target/hexameter-swt-example-1.1.3-SNAPSHOT.jar

Supported operations

  • Querying the characteristics of the HexagonGrid
  • Fetching all the Hexagon objects from the grid
  • Getting a subset of Hexagons (using cube or offset coordinate range) from the grid
  • Checking whether a Hexagon is on a grid or not
  • Getting a Hexagon by its grid coordinate (cube)
  • Getting a Hexagon by its pixel coordinate
  • Getting the neighbors of a hexagon (also by index)

Advanced operations

  • Calculating the distance between two Hexagons
  • Calculating the movement range from a Hexagon to an other
  • Rotating a Hexagon
  • Calculating a ring from a Hexagon
  • Draw a line from a Hexagon to an other
  • Checking visibility of a Hexagon from an other
  • Adding custom data to a Hexagon
  • Clearing all custom data from the HexagonalGrid

Check these interfaces for more details:

Usage tips

  • You can add satellite data (any arbitrary data you have) to a Hexagon. By implementing the SatelliteData interface you gain operations like visibility checking
  • Hexameter comes with a sensible default implementation of SatelliteData so if you don't want to add extra data you can use DefaultSatelliteData.
  • You can use your own implementation of HexagonDataStorage for storing your Hexagons
  • Hexameter comes with a sensible DefaultHexagonDataStorage implementation which stores all data in memory
  • You don't have to fetch all Hexagon objects by using the getHexagons method. You can query Hexagons by a range using offset or cube coordinates

Road map:

  • Path finding with obstacles (blocking movement)
  • Movement range with obstacles and movement cost calculation
  • Android example

License

Hexameter is made available under the MIT License.

Credits

Hexameter is created and maintained by Adam Arold

I'm open to suggestions, feel free to comment or to send me a message. Pull requests are also welcome!