// http://codingtra.in

// http://patreon.com/codingtrain

​

// Sandpiles

// https://youtu.be/diGjw5tghYU

​

let defaultColor = [255, 0, 0];

let colors = [

  [255, 255, 0],

  [0, 185, 63],

  [0, 104, 255],

  [122, 0, 229]

];

​

let sandpiles;

let nextpiles;

​

function setup() {

  createCanvas(600, 600);

  pixelDensity(1);

​

  sandpiles = new Array(width).fill().map(i => new Array(height).fill(0));

  nextpiles = new Array(width).fill().map(i => new Array(height).fill(0));

​

  sandpiles[width / 2][height / 2] = 1000000000;

​

  background(defaultColor[0], defaultColor[1], defaultColor[2]);

}

​

function topple() {

  for (let x = 0; x < width; x++) {

    for (let y = 0; y < height; y++) {

      nextpiles[x][y] = sandpiles[x][y];

    }

  }

​

  for (let x = 0; x < width; x++) {

    for (let y = 0; y < height; y++) {

      let num = sandpiles[x][y];

      if (num >= 4) {

        nextpiles[x][y] -= 4;

        if (x + 1 < width)

          nextpiles[x + 1][y]++;

        if (x - 1 >= 0)

          nextpiles[x - 1][y]++;

        if (y + 1 < height)

          nextpiles[x][y + 1]++;

        if (y - 1 >= 0)

          nextpiles[x][y - 1]++;

      }

    }

  }

​

  let tmp = sandpiles;

  sandpiles = nextpiles;

  nextpiles = tmp;

}

​

function render() {

  loadPixels();

  for (let x = 0; x < width; x++) {

    for (let y = 0; y < height; y++) {

      let num = sandpiles[x][y];

      let col = defaultColor;

      if (num == 0) {

        col = colors[0];

      } else if (num == 1) {

        col = colors[1];

      } else if (num == 2) {

        col = colors[2];

      } else if (num == 3) {

        col = colors[3];

      }

​

      let pix = (x + y * width) * 4;

      pixels[pix] = col[0];

      pixels[pix + 1] = col[1];

      pixels[pix + 2] = col[2];

      // pixels[pix + 3] = 255;

    }

  }

​

  updatePixels();

}

​

function draw() {

  render();

​

  for (let i = 0; i < 50; i++) {

    topple();

  }

}