Tik-76.402 Datateknik B
This is an applet for the cellular automata "Langton's Ant". The original
Langton ant moves about a two-dimensional grid where the fields are either
white or black. If the ant arrives at a black grid square it changes the
color of the square to white and turns to the right. respectively, if the ant
arrives at a white grid square it changes the color of the square to black and
turns to the left.
However, this version of Langton's ant is a tad more complicated than that.
It allows for colors (16 at the moment, but it can easily be modified) and
multiple ants. Each ant is programmable, in the beginning each ant has got
a randomized program, and it is possible to reprogram the ant at runtime.
The program of the ant consists of two instructions for each color. One tells
the ant which color to change to, and the other one tells the ant in which
direction it should continue.
2. User's guide
The applet is almost quite self-explanatory. It has got three parts, the top
panel, the central canvas where the ants move about and the bottom panel.
2.1 The top panel
The top panel contains three buttons, Resume, Pause and Randomize. Of theese
three Randomize is clearly the most important, since the entire simulation
is started by clicking on it. As you probably can guess, the other two buttons
are for pausing and resuming the simulation, respectively.
2.2 The central canvas
This is the place where all the action takes place. You can't really do
anything here, except admire the ants move around. Frenetic mouseclicking
in the canvas will do you no good, except maybe crash your browser, or the
entire computer if you're running Windows(tm).
2.3 The bottom panel
This is the most cryptic part of the user interface, so read carefully!
The bottom panel consists of two rows of gizmos. Let's start the description
by beginning from the upper left gizmo called "New Ant". This gizmo is in fact
a Choice, or a pulldown menu. It allows you to choose an ant and also to add
a new ant. Note that if the simulation hasn't been started, the only choice
available is "New Ant". If the simulation has been started, the additional
choices are "Ant i", where i is an integer. Also note that if you start the
simulation by choosing "New Ant" you can no longer get additional ants by
pressing the randomize button. Let's call the selected item in this menu the
currently selected ant. To the right of the ant choice there is another
pulldown menu, before you touch it titlet "Color 0". This choice contains all
the colors, numbered from 0 to 15 at the moment. With this pulldown menu you
choose what part of the program of the selected ant you want to look at. Let's
call it the currently selected color.
To the right of this choice the are two labels, one contains the text "Change
to color" and the other one "Heading". Theese two show you the currently
selected ants instructions for the selected color. To the right of these
there is an additional pulldown menu, titled "Color0". This is used for
changing the color the current ant changes the currently selected color to.
To the left on the lower row there is a pulldown menu titled "FORWARD".
It is used for changing the heading the current ant changes to when
encountering the currently selected color. To the right of this menu there are
two textfields. They are used if you wish to manually edit the color of the
canvas. Type in the x-coordinate in the left textfield and the y-coordinate
in the right textfield, choose the new color from the pulldown menu labeled
"GridColor 0". Remember that the grid is 150*150 squares, so you must input
values between 0 and 149.