int[][] data = new int[2][20 * 18];
int compute = 1;
int display = 0;

void setup() {
    background(255);
    size(300, 300);
    frameRate(6);
    fill(0);
    noStroke();
    data[display][5 + 50] = 1;
    data[display][6 + 70] = 1;
    data[display][4 + 90] = 1;
    data[display][5 + 90] = 1;
    data[display][6 + 90] = 1;
} 

void draw() {
    // corners
    conway(0, 1, 21, 20, 39, 19, 359, 340, 341); // top left
    conway(19, -19, 1, 20, 19, -1, 339, 340, 321); // top right
    conway(340, 1, -339, -340, -321, 19, -1, -20, -19); // bottom left
    conway(359, -19, -359, -340, -341, -1, -21, -20, -39); // bottom right
    
    // border rows
    for (int i = 1; i < 19; i++)
    {
        conway(i, 1, -1, 20, 19, 21, 340, 339, 341); // top
        conway(i + 340, -1, 1, -340, -339, -341, -20, -21, -19); // bot
    }
    
    // border columns
    for (int i = 20; i < 340; i += 20)
    {
        conway(i, 1, 21, 20, 39, 19, -1, -20, -19); // left
        conway(i + 19, -19, 1, 20, 19, -1, -21, -20, -39); // right
    }
    
    // inner
    for (int y = 20; y < 340; y += 20)
        for (int x = 1; x < 19; x++)
        {
            int i = x + y;
            conway(i, 1, -1, 20, 21, 19, -20, -21, -19);
        }       
  
    //fill(255, 16);
    //rect(0, 0, 20*10+10, 18*10+10);
    background(255);

    fill(0);
    for (int i = 0; i < 20*18; i++)
    {
        if (data[display][i] == 1)
        {
            int x = i % 20;
            int y = (int)(i / 20);
            ellipse(x * 10 + 5, y * 10 + 5, 5, 5);
        }
    }
    compute = 1 - compute;
    display = 1 - display;
}

void conway(int idx, int c0, int c1, int c2, int c3, int c4, int c5, int c6, int c7)
{
    int count = data[display][idx+c0] + data[display][idx+c1] + data[display][idx+c2]
		+ data[display][idx+c3] + data[display][idx+c7] + data[display][idx+c6]
		+ data[display][idx+c5] + data[display][idx+c4];
    if (data[display][idx] == 1)
        data[compute][idx] = (count == 2 || count == 3) ? 1 : 0;
    else
        data[compute][idx] = count == 3 ? 1 : 0;
}