Warm-Up Project: The Game of Life
CS 7492, Spring 2021
There are several goals for this assignment. The first is for each of
you to gauge your own programing skills and to verify that you will be able
to do the later assignments. The second goal is to introduce you to
the Processing language and development environment, since we will use
it for all of the assignments. Finally, this project will give you
some experience working with Cellular Automata.
We will use a language called "Processing" to carry out this (and
later) assignments. Processing is a language very similar to C++ and
Java, but it has a number of extra items that make it very easy to
write simple interactive programs. Processing runs on several platforms,
including Windows, Mac OS X and Linux. The main processing Web site is here:
I recommend looking at some example code to start with:
http://www.processing.org/learning/basics/ (Basic examples)
Documentation for various built-in routines are here:
Download the appropriate version of the development environment
for your machine:
The development environment is described here:
You can also try out Greg's
simple example code
(shown in class).
Run the Processing environment and play around with it. I suggest
starting with code from the examples page and modifying some examples
to try new things.
A Life Simulator
You will write a cellular automata simulator for the game
of Life, originally create by John Horton Conway. Life is
simulated on a square grid of cells. Each cell is either
live (white) or dead (black). The rules for life are simple.
At each simulation step, a cell changes its live/dead state
according to its last state and the number of live cells adjacent to
it. Each cell is said to have eight neighbors, that is, diagonal
neighbors count. The rules are simple: a live cell continues to
live if it has two or three live neighbors. A dead cell is turned
into a live cell if it has exactly three live neighbors. All other
cells will be dead.
Your program will display the state of the simulation in a window
that contains black and white cells. Here are some of the characteristics
of this window:
You will write a Life simulator that allows a user to create cell
patterns by mouse clicks. When the user clicks on a black cell, it
is turned to white. Clicking on a white cell changes it to black.
Your simulator will also run in either of two modes: single-step
or continuous. Various keys will control the behavior of your
simulator. Here are the key controls and their behavior:
- The grid will be 100 by 100 cells.
- Each cell should be at least six by six pixels in size (thus the
screen must be at least 600 by 600 pixels).
- The grid of cells is toroidal, that is, cells on the far left edge
are neighbors to the cells on the far right edge. The top and bottom
rows are also adjacent.
If you would like to try out another Life simulator, I recommend the Golly simulator.
- c,C - Clear the grid to all black.
- r,R - Randomize the state of the grid (each cell is black or
white with equal probability).
- g,G - Toggle between single-step and continuous update mode.
- space bar - Switch to single-step mode and take one simulation step.
Routines to Use
The built-in functions for Processing are documented on this page:
There are several Processing functions that will be of particular
help in doing this assignment. Here are some of them:
This is a routine that you must write. This routine is executed once when
the program is first run. This is where you should set the screen size and
initialize your rule table and cell grid.
This is a routine that you write, and it is the main loop for any
Processing program. The code here will be executed continuously.
When your program is in continuous update mode, this routine should
take a simulation step and re-draw the grid.
This routine is called when any key on the keyboard is pressed. You should
then use "key" to check which key was pressed.
This routine is called when a mouse button is pressed. Inside this
routine, you will want to make use of the values of "mouseX" and "mouseY"
to determine where the cursor was on the screen.
Set the fill color and the outline color for objects that are to be drawn,
such as a rectangle.
Draws a rectangle using on the current stroke and fill color.
Set the color of the screen background.
Returns a floating point random number.
Pauses the execution of your program for a given number of milliseconds.
This can be useful for debugging.
If you are already comfortable programming in C, C++ or Java, you
can skip this section. If you haven't done much programming in a
while, I offer below some suggestions for how to approach this assignment.
As with any programming project, it is best to write it in pieces and
to test these pieces as you go.
First, create a data structure that will hold your grid of cells.
Also write a few lines of code that places a simple life pattern
(such as a glider) into your grid. Then write code to display the
current grid of cells on the screen. As you write various pieces
of code, try to keep each of them in a separate routine, that is,
keep your code modular. For instance, your final code probably should
have three separate routines for clearing, drawing and randomizing the
grid of cells.
Once you can store and display a grid of cells, then it is time
to work on user input. Play around with the "mousePressed()"
routine and the variables "mouseX" and "mouseY". You will need
to have a routine called "draw()", although it doesn't have to do
anything at this point. You should be
able to have a user click at a point on the screen, and then
use this click position to alter the state of one of the cells in
your grid (toggle it between white and black). Be sure to re-draw
the grid of cells after each such user click.
Once you have the basics of mouse input down, you can add to your
"draw()" routine. Each time through this routine, have your program
perform one simulation step. This is a matter of using a temporary
grid that contains a count of the number of neighbors for each cell
in the main grid. With this count grid, you can then go through
each cell in the grid and look up the appropriate state/count pair
in your rule table to determine the new state of the cell. You may
want to insert a "delay(1000)" in your draw routine to slow down
the execution of your code during debugging. This will cause your
program to pause for one second each time this line is executed.
After your program can take simulation steps, it is time to add
the other key press behaviours. Use "keyPressed()" and the variable
called "key" to do this.
Turning In Your Assignment
Turn in your Processing source code for this project on Canvas. You can
turn in just one .pde file if all of your code is in a single file. If
your project contains more than one file, you should zip up the entire
project directory and turn this in.
The code that you turn in must be entirely your own. You are allowed to
talk to other members of the class and to the teacher about general
implementation issues. It is also fine to seek the help of others for
general programming questions about Processing. You may not, however, use
code that anyone other than yourself has written. Code that is explicitly
not allowed includes code taken from the Web, from books, from previous
assignments or from any source other than yourself. You should not show
your code to other students. Feel free to seek the help of the teacher
for suggestions about debugging your code.