// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(1);

const PI2 = Math.PI * 0.5;
const PI4 = Math.PI * 0.25;
const SQRT2 = Math.sqrt(2)

const STARTX = -100
const STARTY = -100

var marginx = 0
var marginy = 0
var iter = 0;

const cols = 12  // min=8, max=100, step=1
const rows = 22  // min=8, max=100, step=1
const side = 6;  // min=2, max=20, step=1

var r = side * SQRT2;

// Global code will be evaluated once.
const turtle = new Turtle();
turtle.penup();
turtle.goto(-100,-100);

// The walk function will be called until it returns false.
function walk(i) {
  marginx = (200 - cols*r)/2
  if (marginx<0) marginx=0
  for (row = 1; row <= rows; row++) {
    for (col = 1; col <= cols; col++) {
      drawQuad(col, row);
    }
  }
  return false
}

function drawQuad(p, q) {
  step = iter / 264;
  d = {min:-side * step, max: side * step};
  a = { min: PI4 * (1 - step), max: PI4 * (1 + step) };
  psi = map(Math.random(), 0,1, a.min, a.max)

  x = STARTX + marginx + p*r + map(Math.random(),0,1,d.min, d.max)
  y = STARTX + marginy + q*r + map(Math.random(),0,1,d.min, d.max)

  for (s = 0; s <= 4; s++) {
    if (s==0) turtle.penup()
    else turtle.pendown()
    psi += PI2;
    turtle.goto(x+side * Math.cos(psi), y+side * Math.sin(psi));
  }
  turtle.penup()
  iter += 1;
}


function map(number, inMin, inMax, outMin, outMax) {
    return (number - inMin) * (outMax - outMin) / (inMax - inMin) + outMin;
}