by Mike Davis. A short program for alife experiments. Click in the window to restart. Each cell is represented by a pixel on the display as well as an entry in the array 'cells'. Each cell has a run() method, which performs actions based on the cell's surroundings. Cells run one at a time (to avoid conflicts like wanting to move to the same space) and in random order.
Original Processing.org Example: Spore1
// All Examples Written by Casey Reas and Ben Fry // unless otherwise stated. World w; int numcells = 0; int maxcells = 4700; Cell[] cells = new Cell[maxcells]; color spore_color; // set lower for smoother animation, higher for faster simulation int runs_per_loop = 100; color black = color(0, 0, 0); void setup() { size(200, 200); frameRate(24); clearscr(); w = new World(); spore_color = color(172, 255, 128); seed(); } void seed() { // Add cells at random places for (int i = 0; i < maxcells; i++) { int cX = (int)random(width); int cY = (int)random(height); if (w.getpix(cX, cY) == black) { w.setpix(cX, cY, spore_color); cells[numcells] = new Cell(cX, cY); numcells++; } } } void draw() { // Run cells in random order for (int i = 0; i < runs_per_loop; i++) { int selected = min((int)random(numcells), numcells - 1); cells[selected].run(); } } void clearscr() { background(0); } class Cell { int x, y; Cell(int xin, int yin) { x = xin; y = yin; } // Perform action based on surroundings void run() { // Fix cell coordinates while(x < 0) { x+=width; } while(x > width - 1) { x-=width; } while(y < 0) { y+=height; } while(y > height - 1) { y-=height; } // Cell instructions if (w.getpix(x + 1, y) == black) { move(0, 1); } else if (w.getpix(x, y - 1) != black && w.getpix(x, y + 1) != black) { move((int)random(9) - 4, (int)random(9) - 4); } } // Will move the cell (dx, dy) units if that space is empty void move(int dx, int dy) { if (w.getpix(x + dx, y + dy) == black) { w.setpix(x + dx, y + dy, w.getpix(x, y)); w.setpix(x, y, color(0)); x += dx; y += dy; } } } // The World class simply provides two functions, get and set, which access the // display in the same way as getPixel and setPixel. The only difference is that // the World class's get and set do screen wraparound ("toroidal coordinates"). class World { void setpix(int x, int y, int c) { while(x < 0) x+=width; while(x > width - 1) x-=width; while(y < 0) y+=height; while(y > height - 1) y-=height; set(x, y, c); } color getpix(int x, int y) { while(x < 0) x+=width; while(x > width - 1) x-=width; while(y < 0) y+=height; while(y > height - 1) y-=height; return get(x, y); } } void mousePressed() { numcells = 0; setup(); }