Rhex

This repository contain a library for using a grid of hexagons with ruby.

It is a partial ruby implementation of the huge work of Amit Patel (http://www.redblobgames.com/grids/hexagons/).
The hexagons are pointy topped.
The coordinate system is axial.
Only required methods are implemented in the cube object.

Compatibility

This gem has been tested with ruby 2.4, 2.5, 2.6

Setup

gem install rhex

Or in your gemfile :

gem 'rhex'

Then in your code :

require 'rhex'

Usage

Basics

# Create a new hexagon (q = 10, r = 10 )
# To understand what q and r mean, please have a look at http://www.redblobgames.com/grids/hexagons/#coordinates
hexa = AxialHex.new( 10, 10 )
# => #<AxialHex @q=10, @r=10>

# Get hexes surrounding it
hexa.surrounding_hexs
# => [#<AxialHex @q=10, @r=9>, #<AxialHex @q=11, @r=9>, ... ]

# Get distance between two hexagons
hexb = AxialHex.new( 20, 20 )
hexa.distance(hexb)
# => 20

# Check if a hex is adjacent to another hex
hexa.hex_surrounding_hex?(hexb)
# => false

# Get the nearset hex from a hexes list
hexc = AxialHex.new( 20, 13 )
hlist = [ hexb, hexc ]
hexa.nearest_hex(hlist)
# => #<AxialHex @q=20, @r=13>

Hexagons grid

Hexagons by themselves are not really useful. What we need is an hexagon grid.

# Create an hexagon grid
g = AxialGrid.new
# => #<AxialGrid @hexes={}, @element_to_color_hash={}, @hex_ray=16, @hex_height=32.0, @hex_width=27.712812921102035, @half_width=13.856406460551018, @quarter_height=8.0>

# Add an hexagon to the grid
g.cset( 5, 8 )
# => #<AxialHex @q=5, @r=8, @border=false>

# Get an hexagon from the grid
g.cget( 5, 8 )
# => #<AxialHex @q=5, @r=8, @border=false>

g.cget( 5, 4 )
# => nil

Reading a grid from an ascii file

It will be far more fun to create your hex map from an ascii map. For example, if you have the following map :

m m g g m m m m m
 m g g g m m m m g
m g w w g m m m m
 m g w w w g m g g
g w w w w g g g w
 g w w w w w g g g
g g w w w g g g m
 g g g w w g g m m
g g g g w g g g g
 g g g g w g g g g
g g g g g w g g g
 g g g g w g g g g
g g g g w g g g g

Where m = mountains, g = grass and w = water. If this map is in a file called for instance : ascii_map.txt then :

# CAUTION : don't use an axial grid for that, your asciimap is square
g = SquareGrid.new

# Load it with 
g.read_ascii_file( 'test/ascii_map.txt' )

# Get an hex 
g.cget( 5, 5 )
# => <AxialHex @q=5, @r=5, @color="w", @data=nil>

# Get an hex value
g.cget( 5, 5 ).color
# => "w"

# Borders don't work, will be fixed
# Check if the hex is at the border of the map or not 
# g.cget( 5, 5 ).border
# => nil
# g.cget( 0, 0 ).border
# => true

Dumping an hex map (require rmagick - see http://rmagick.rubyforge.org/install-faq.html)

You can dump a grid to a bitmap file. In order to have different colors for your hex map, you need to specify them when creating the grid.

  element_to_color_hash: {
    m: :brown, g: :green, w: :blue, u: '#e3e3e3'
  }

Where m = brown, g = green and w = blue (the colors for mountains, grass and water - u mean unused, its only to show an example of RGB notation). I used rmagick to create the bitmap, so all rmagick color syntax are available : http://www.simplesystems.org/RMagick/doc/imusage.html#color_names.

# Create a grid with a correspondence array from val to color
g = SquareGrid.new(
  element_to_color_hash: {
    m: :brown, g: :green, w: :blue
  }
)

# Load the same map we used before
g.read_ascii_file( 'test/ascii_map.txt' )

# Create the pic
g.to_pic( 'test2.png' )

You should get your map as an hex bitmap grid :

czuger/rhex