Conway's Game Of Life running on an Arduino, displaying on a string of RGB LEDs arranged in a matrix

LifeInColor.pde

/*
 * Conway's "Life"
 * 
 * Adapted from the Life example
 * on the Processing.org site
 *
 * Written by David Kavanagh (dkavanagh@gmail.com).  
 */
#include "SPI.h"
#include "Adafruit_WS2801.h"

int dataPin  = 2;    // Yellow wire on Adafruit Pixels
int clockPin = 3;    // Green wire on Adafruit Pixels

Adafruit_WS2801 display = Adafruit_WS2801((uint16_t)7, (uint16_t)7, dataPin, clockPin);

#define DELAY 300
#define SIZE 7
extern byte leds[SIZE][SIZE];
byte world[SIZE][SIZE][3]; // 0=currentgen, 1=nextgen, 2=age
long density = 50;
uint32_t colors[8] = {0x000000, 0x444400, 0x004444, 0x440044, 0x880000, 0x008800, 0x000088, 0x999999};

void setup() {
  display.begin();
  display.show();
  randomSeed(analogRead(5));

}

void randomize() {
  for (int i = 0; i < SIZE; i++) {
    for (int j = 0; j < SIZE; j++) {
      if (random(100) < density) {
        world[i][j][0] = 1;
      }
      else {
        world[i][j][0] = 0;
      }
      world[i][j][1] = 0;
      world[i][j][2] = 0;
    }
  }
}
  
void loop() {
  // Display current generation
  for (int i = 0; i < SIZE; i++) {
    for (int j = 0; j < SIZE; j++) {
      display.setPixelColor(i, j, colors[world[i][j][2]]);
    }
  }
  display.show();
  delay(DELAY);

  // Birth and death cycle 
  for (int x = 0; x < SIZE; x++) { 
    for (int y = 0; y < SIZE; y++) {
      // Default is for cell to stay the same
      world[x][y][1] = world[x][y][0];
      int count = neighbours(x, y); 
      if (count == 3 && world[x][y][0] == 0) {
        // A new cell is born
        world[x][y][1] = 1;
      }
      if (world[x][y][2] < 7) {
        world[x][y][2] += world[x][y][1];
      }
      if ((count < 2 || count > 3) && world[x][y][0] == 1) {
        // Cell dies
        world[x][y][1] = 0;
        world[x][y][2] = 0;
      }
    }
  }
  
  boolean changes = false;
  // Copy next generation into place
  for (int x = 0; x < SIZE; x++) { 
    for (int y = 0; y < SIZE; y++) {
      if (world[x][y][0] != world[x][y][1]) {
        changes = true;
      }
      world[x][y][0] = world[x][y][1];
    }
  }
  if (!changes) {
    randomize();
  }
}

int neighbours(int x, int y) {
 return world[(x + 1) % SIZE][y][0] + 
         world[x][(y + 1) % SIZE][0] + 
         world[(x + SIZE - 1) % SIZE][y][0] + 
         world[x][(y + SIZE - 1) % SIZE][0] + 
         world[(x + 1) % SIZE][(y + 1) % SIZE][0] + 
         world[(x + SIZE - 1) % SIZE][(y + 1) % SIZE][0] + 
         world[(x + SIZE - 1) % SIZE][(y + SIZE - 1) % SIZE][0] + 
         world[(x + 1) % SIZE][(y + SIZE - 1) % SIZE][0]; 
}