im so fuckin' _dangerously defensive_. bite me.

20170106.js

// ulam spiral leggo

var start;
var N;
var sideLen;

function setup() {
  createCanvas(500,500);
  background(0);
  sideLen = 20;
  N = 401;
  rectMode(CENTER);
  start = createVector(width/2, height/2);
  noLoop();
}

function draw() {
  var loopsAround = 0;
  // how the fuck do i draw a spiral
  // this was a programming question that i once failed
  // this is taking me absurdly long

  drawSq(start.x, start.y, 1);

  for (var i = 2; i < N; i++) {
    var nextLargestSq = Math.ceil(Math.sqrt(i));
    var spiralSide = nextLargestSq%2 == 0 ? nextLargestSq+1 : nextLargestSq;
    var tier = Math.floor(spiralSide/2); // integer diviz?
    var numPerSide = spiralSide-1;
    var prevSpiralSide = 2*tier - 1;
    var thisTierStart = Math.pow(prevSpiralSide, 2) + 1;
    //console.log("i", i, "spiralside", spiralSide, "tier", tier, "number per side in this spiralside", numPerSide, "previous spiral side length", prevSpiralSide, "this tier starts at",thisTierStart);
    // these names are horrible. i am truly sorry.
    var sideIdx = ((i - thisTierStart)%numPerSide) + 1;
    var relSideIdx = sideIdx - tier;
    var side = Math.floor((i - thisTierStart)/numPerSide)+1;

    var dx, dy;
    // giant switch statement? lol
    if (side == 1) {
      dx = tier;
      dy = -1*relSideIdx;
    } else if (side == 2) {
      dx = -1*relSideIdx;
      dy = -1*tier;
    } else if (side == 3) {
      dx = -1*tier;
      dy = relSideIdx;
    } else {
      dx = relSideIdx;
      dy = tier;
    }

    var coorx = start.x + dx * sideLen;
    var coory = start.y + dy * sideLen;

    drawSq(coorx, coory, i);
  }
}

function drawSq(x, y, num) {
  // check properties of num and color accordingly

  var rectColor = color(0,0,0);
  if (isPrime(num)) {
    rectColor = color(200,200,0);
  }

  fill(rectColor);
  stroke(255);
  rect(x, y, sideLen, sideLen);

  fill(255);
  noStroke();
  textSize(10);
  textAlign(CENTER, CENTER);
  var num = "" + num;
  text(num, x, y);
}

function isPrime(num) {
  // yeah fuck you too this part isn't the point of this project
  // #dangerouslyDefensive
  if (num == 1) { return false; }
  for (var i = 2; i <= Math.sqrt(num); i++) {
    if (num%i == 0) {
      return false;
    }
  }
  return true;
}