/*
  Reference: https://makezine.com/2011/05/11/codebox-explore-recursion-with-processing/
*/
 
let number = 3;  // Number of recursive steps
 
//Draw the first image
function setup() {
  createCanvas(500, 500);
  piet(1, 1, 500, 500, number);
}

// Draw a Mondarian-inspired image using recursion
function piet(x0, y0, x1, y1, N) {
  if (N == 0) {
    // Base case -- draw a colorful rectangle with a thick black border 
    let sw = 10; //this is the stroke width for the rectangle's border
    let c = ['#ff0000', '#0000ff', '#ffff00', '#ffffff']; //Mondarian color palatte    
    fill(c[int(random(c.length))]);
    stroke(0);
    strokeWeight(sw);
    rect (x0, y0, x1-x0, y1-y0);
    return;
  } else {
    //Recursive step -- recursively break the current rectangle into 4 new random rectangles
    let i = int(random(x0, x1)); //Pick a random x coordinate inside the current rectangle
    let j = int(random(y0, y1)); //Pick a random y coordinate inside the current rectangle
    piet(x0, y0, i, j, N-1); // Recurse on upper left rectangle
    piet(i, y0, x1, j, N-1); // Recurse on upper right rectangle
    piet(x0, j, i, y1, N-1); // Recurse on lower left rectangle
    piet(i, j, x1, y1, N-1); // Recurse on lower right rectangle
    return;
  }  
  //save("mondorian.png");
}
 
// keep draw() here to continue looping while waiting for keys
function draw() {
}
 
//Draw a new image each time a key is pressed
function keyPressed() {
  background(0);
  piet(1, 1, 500, 500, number);
}