Ulam Prime Spiral [Base]

let x,y;

let px, py;

let step = 1;

let stepSize = 20;

let numSteps = 1;

let state = 0;

let turnCounter = 0;

​

function isPrime(value) {

  if (value == 1) return false;

  for (let i = 2; i <= sqrt(value); i++) {

    if (value % i == 0) {

      return false;

    }

}

return true;

}

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  x = width / 2;

  y = height / 2;

  px = x;

  py = y;

  background(0);

}

​

function draw() {

  text(step, x, y);

  fill(50);

  stroke(50);

  rectMode(CENTER);

  square(x, y, stepSize);

  fill(255,255,0);

  stroke(255,255,0);

  strokeWeight(1);

  line(x, y, px, py);

  px = x;

  py = y;

  fill(255,255,0);

  stroke(255,255,0);

  if (isPrime(step)) {

    circle(x, y, stepSize * 0.75);

    fill(255,0,0);

    stroke(255,0,0);

    textSize(stepSize/2);

    textAlign(CENTER,CENTER);

    text(step, x, y);

  }

  //SWITCH

  switch(state){case 0:x+=stepSize;break;case 1:y-=stepSize;break;case 2:x-=stepSize;break;case 3:y+=stepSize}

​

  if (step % numSteps == 0) {

    state = (state + 1) % 4;

    turnCounter++;

    if (turnCounter % 2 == 0) {

      numSteps++;

    }

    if (turnCounter == 70) {

      noLoop();

    }

  }

  step++;

}