// Note that it is possible to randomly get a boring rug. Just press play again until you get a nice one!

​

// Read about the Persian rug algorithm; https://archive.bridgesmathart.org/2005/bridges2005-9.pdf

​

// Learn more here: https://github.com/kfahn22/Persian-Rug

​

// To learn more about recursion, watch Daniel Shiffman's Recursion Coding Challenge

// https://thecodingtrain.com/challenges/77-recursion

​

// Based on this Processing sketch (https://github.com/kfahn22/Persian-Rug/blob/main/sketch.pdez), which is adapted from https://stackoverflow.com/questions/26226531/persian-rug-recursion

​

// I am using the method for choosing colors from Dr. Eric Gossett https://www.youtube.com/watch?v=0wfPlzPvZiQ

​

let n = 10; 

let sw = 2;  // Adjust as desired to change look of rug

let palette = [];

let colorIndexArray = [];

​

​

// I am getting the palette from supercolorpalette.com because this is a convienent way to get a consistent color array with 12 values

let url = "https://supercolorpalette.com/?scp=G0-hsl-FFDA1F-FBAC23-F68128-F25A2C-1FB4FF-23DEFB-28F6E8-2CF2BD-691FFF-4023FB-2835F6-2C61F2"

​

// Helper functions to convert the url to the color palette

function extractHexCodes(url) {

  let startIndex = url.indexOf("=");

  let hexPart = url.substring(startIndex + 1);

  let parts = hexPart.split("-");

​

  // Filter valid hex codes

  return parts.filter((part) => /^[0-9A-Fa-f]{6}$/.test(part));

}

​

function hexToColor(hex) {

  let r = parseInt(hex.substring(0, 2), 16);

  let g = parseInt(hex.substring(2, 4), 16);

  let b = parseInt(hex.substring(4, 6), 16);

  return color(r, g, b);

}

​

function generatePaletteArray(url) {

  let hexCodes = extractHexCodes(url);

  return hexCodes.map((hex) => hexToColor(hex));

}

​

function setup() {

  let canvasSize = Math.pow(2, n) + 1; // 257 x 257 for n = 8

  createCanvas(canvasSize, canvasSize);

  noLoop();

  palette = generatePaletteArray(url);

  //console.log(palette);

​

  // Initialize the color index array

  colorIndexArray = Array(canvasSize)

    .fill()

    .map(() => Array(canvasSize).fill(0));

​

  // Draw border

  let w = canvasSize - 1;

  drawBorder(0, 0, w, w, 0);

​

  // Choose colors for the internal grid

  let shift = floor(random(1, palette.length));

  chooseColor(0, w, 0, w, shift);

​

  // Save the result

  // saveCanvas("persian_rug", "jpg");

}

​

function drawBorder(left, top, right, bottom, colorIndex) {

  let c = palette[colorIndex];

  stroke(c);

  strokeWeight(sw);

  line(left, top, right, top); // Top

  line(left, bottom, right, bottom); // Bottom

  line(left, top, left, bottom); // Left

  line(right, top, right, bottom); // Right

}

​

function chooseColor(left, right, top, bottom, shift) {

  if (left < right - 1) {

    let newIndex =

      (getIndex(colorIndexArray[left][top]) +

        getIndex(colorIndexArray[right][top]) +

        getIndex(colorIndexArray[left][bottom]) +

        getIndex(colorIndexArray[right][bottom]) +

        shift) %

      palette.length;

​

    let col = palette[newIndex];

    let midCol = floor((left + right) / 2);

    let midRow = floor((top + bottom) / 2);

​

    // Draw middle lines

    stroke(col);

    strokeWeight(sw);

    line(left + 1, midRow, right - 1, midRow); // Horizontal

    line(midCol, top + 1, midCol, bottom - 1); // Vertical

​

    // Update color index array

    colorIndexArray[midCol][midRow] = newIndex;

​

    // Recursive calls

    chooseColor(left, midCol, top, midRow, shift);

    chooseColor(midCol, right, top, midRow, shift);

    chooseColor(left, midCol, midRow, bottom, shift);

    chooseColor(midCol, right, midRow, bottom, shift);

  }

}

​

function getIndex(colorIndex) {

  // Directly use the color index from the array

  return colorIndex;

}

​

// function mousePressed() {

//   save("rug.png");

// }

​