Sawtooth

let t = 0;
let n = 25;
let rs;
let domain;

function setup() {
  domain = [-2 * PI, 2 * PI];
  createCanvas(500, 500);
  background(255);
  describe(
    "arcs of sawtooth and scribbly curves drawn on radial graph paper with larger arcs at the edges and smaller towards the center. The sketch is staticky and with greys and whites. "
  );
  rectMode(CENTER);
  strokeWeight(0.5);
  strokeCap(SQUARE);
  rs = [];
  t = random(-10, 10);
  r1 = random([3, 5, 6, 10]);
  r2 = r1 + 1;
  r3 = random([-2, -3, -4]);
  r4 = random([-1, -5, -6]);
  for (let i = 0; i < 30; i++) {
    rs[i] = random([-6, -7, -8, -10, 8, 7, 6, 10]);
  }
}

function draw() {
  background(245, 250, 255, 20);
  translate(width / 2, height / 2);
  stroke(100, 110, 120, 10);
  drawGrid();
  t += 0.002;
  noFill();
  stroke(80, 90, 100);
  for (let j = 0; j < 35; j++) {
    stroke(j * 5 + 20, j * 5 + 30, j * 5 + 40, 20);
    strokeWeight(abs(rs[j]));
    push();
    r = (width / 25) * 15 - (j * (width / 25)) / 2;
    beginShape();
    cnt = 0;
    for (let i = domain[0]; i < domain[1]; i += 0.5) {
      cnt++;
      if (cnt % 2 === 0) {
        vertex(
          r * cos(i / rs[j + 1] + t / rs[j] + j * 2),
          r * sin(i / rs[j + 1] + t / rs[j] + j * 2)
        );
      } else {
        vertex(
          r * cos(i / rs[j] + t / rs[j] + j * 2) * 0.95,
          r * sin(i / rs[j] + t / rs[j] + j * 2) * 0.95
        );
      }
    }
    endShape();
    pop();
  }
  if (frameCount % 500 == 0) {
    r1 = random([1, 2, 4, 5]);
    r2 = random([3, 3, 6, 7]);
    r3 = random([-2, -3, -4]);
    r4 = random([-1, -5, -6]);
  }

  strokeWeight(1);
  noFill();
  stroke(100, 110, 120, 30);
  rect(0, 0, width / 1.02, width / 1.02);
  rect(0, 0, width / 1.04, width / 1.04);
}

function drawGrid() {
  for (let i = 0; i < n; i++) {
    rotate((2 * PI) / n);
    line(-width / 1.5, 0, width / 1.5, 0);
    circle(0, 0, (width / n) * 2 * i);
  }
  noStroke();
  for (let i = 0; i < 500; i++) {
    x = random(-width / 2, width / 2);
    y = random(-width / 2, width / 2);
    fill(245, 250, 255, 150);
    circle(x, y, 2);
  }
}

function mousePressed() {
  setup();
  draw();
}