​

function setup() {

  createCanvas(800, 800);

  translate(0,0);

  noFill();

  let w = 400;

  let h = 400;

             // NW    // NE   // SW                           // SE

  quadtree = [2,0,0,0,

              3,0,0,0,3,0,0,0,3,0,0,0,

              4,0,0,0,4,0,0,0,4,0,0,0,4,0,0,0,

              2,0,0,0,

              2,0,0,0]

  // # draw quadtree

  let cursor = createVector(0,0); // top left of blocks of 4 rectangles

  let context = 2;

  let qid = -1 ;

  let retenue = [];

  for(let i = 0 ; i < quadtree.length ; i+=4){

    strokeWeight(0.5 + i / 10); // # graphics

    stroke(0,10*i,20*i);

    let subdiv = quadtree[i] - 1;

    let qwidth = w/2**subdiv; // cell width

    let qheight = h/2**subdiv; // cell height

    if(context == quadtree[i]){ // no subdivision

      qid += 1; // we move forward to next quadrant id

    }

    else{ // there is a subdivision

      retenue.push([context, cursor, qid+1]) // put in retenue the rect that we are subdividing

      print(retenue);

      cursor = getCursor(context, cursor, qid+1) // qid + 1 of old cursor and old context

      context = quadtree[i];

      qid = 0;

      print(cursor)

    }

    getRect(context, cursor, qid);

    if(qid == 3){

      // GET ONLY THE LAST OF THE RETENUE

      context = retenue[0][0];

      cursor = retenue[0][1];

      qid = retenue[0][2];

      // THEN POP THE LAST ELEMENT OF THE RETENUE

    }

​

  }

  function getRect(context, cursor, qid){

    let rectw = w/2**(context - 1); // context - 1 is the number of subdivisions

    let recth = h/2**(context - 1);

    let x = 0;

    let y = 0;

    if(qid == 1 || qid == 3) { x = rectw; }

    if(qid > 1) { y = recth; }

    let rectx = cursor.x + x;

    let recty = cursor.y + y;

    rect(rectx,recty,rectw, recth);

  }

  function getCursor(context, cursor, qid){

    let rectw = w/2**(context - 1); // context - 1 is the number of subdivisions

    let recth = h/2**(context - 1);

    let x = 0;

    let y = 0;

    if(qid == 1 || qid == 3) { x = rectw; }

    if(qid > 1) { y = recth; }

    let rectx = cursor.x + x;

    let recty = cursor.y + y;

    let newCursor = createVector(rectx,recty);

    return newCursor;

  }

}

​

function draw() {

  //background(220);

​

}