kame (Japanese for turtle)

kame is an implementation of the Logo programming language built as a challenge to myself. I wanted a simple way to introduce programming in Ruby to my daughter and thought this would be fun.

With kame, you control the movement of a turtle around a piece of paper by programming commands. With these simple commands your turtle will draw you a picture.

It's a nice introduction to programming for kids and will also help their maths :o)

What it does

You create a Ruby file with commands that instructs a turtle (kame) to move around. You can tell the turtle to move forward or backward, rotate, put his pen down on the paper or pick it up. You can also change the colour of the pen and paper.

The turtle starts in the top left corner of the kame window facing to the right and will move from there depending on your commands.

Each command is on a new line and they are executed in order.

As this is using Ruby, you also have access to Ruby constructs such as loops and functions.

Platforms

I've tested this on OSX Snow Leopard and also Windows 7. Both work fine :o) It should also work on OSX Lion and Linux in theory, but I haven't tested this yet. Please let me know if you try it.

Install

gem install kame

Simple Sample

Create a new text file called square.rb and paste the below code in and save it:

require "kame"

Kame.new do
  forward 100
  turn_right 90
  forward 100

  colour :red
  pen_down

  4.times do
    turn_right 90
    forward 50     
  end
end

More samples

You can find more samples in my kame_samples repro. One of which is this little flower <3

kame flower

Running

In the console use this:

ruby square.rb

Commands

To move the turtle forward by 50 pixels from it's current position, you can use the forward command:

forward 50

To move the turtle backward by 75 pixels from it's current position, you can use the backward command:

backward 75

You can change the colour of the turtle's pen at any time (on the paper or not) with the colour command:

colour :pink

To tell the turtle to put his pen down onto the paper use the pen_down command. There is an optional parameter for the pen colour to switch to, if not supplied the pen is not changed:

pen_down
pen_down :red

To tell the turtle to pick his pen up again, use the pen_up command:

pen_up

You can ask the turtle to rotate 90 degrees to the left (anti-clockwise) on the spot without moving by using the turn_left command:

turn_left 90

You can ask the turtle to rotate 90 degrees to the right (clockwise) on the spot without moving by using the turn_right command:

turn_right 90

Colours

Here is a list of the available colours:

:white
:black
:red
:green
:blue
:yellow
:pink
:grey
:orange
:purple
:brown
:peach
:turquoise
:silver
:gold
:violet

Options

In addition to commanding the turtle, there are some options you can specify. You pass these options to the Kame constructor like so:

Kame.new(:width => 800, :height => 600) do
    ...
end

Here is a list of all options with their default values (all are optional):

:width => 640                       # The width of the paper in pixels
:height => 480                      # The height of the paper in pixels
:paper => :white                    # The colour of the paper (from the list above)
:title => 'Kame'                # The window title
:speed => 10                            # The speed that the turtle draws. This is how many lines per second should be drawn

:grid => false # Should the help grid be displayed (true | false)? :grid_size => 8 # If the help grid is displayed, this is how many rows and columns should be drawn :grid_colour => :silver # If the help grid is displayed, this is the colour for the grid (from the list above)

Contributing to kame

Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet
Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it
Fork the project
Start a feature/bugfix branch
Commit and push until you are happy with your contribution
Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.