Polar walker - OpenProcessing

mySketch
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// For the #WCCCHallenge "branching"
​
// Just a random walker in polar coordinates. Sometimes, it randomly branches into a new walker
​
let cw, ch
let agents
function setup() {
  cw = windowWidth
  ch = windowHeight
  createCanvas(cw, ch)
  background('#E2E2E2')
  angleMode(DEGREES)
  drawingContext.shadowOffsetX = 5
  drawingContext.shadowOffsetY = 5
  drawingContext.shadowBlur = 10
  drawingContext.shadowColor = 'rgba(0,0,0,0.2)'
  agents = []
  for (let i = 0; i < 4; i++) {
    agents.push({
      r: 0,
      a: 90 * i,
      dir: 1,
      color: random(0, 160)
    })
  }
}
​
function draw() {
  translate(cw/2, ch/2)
  noFill()
  for (let agent of agents) {
    stroke(agent.color)
    strokeWeight(map(agent.r, 0, min(cw, ch), 0.5, 4))
    // If agent is out of bounds, mark it for deletion
    let x = agent.r * cos(agent.a)
    let y = agent.r * sin(agent.a)
    if (x > cw/2 || x < -cw/2 || y > ch/2 || y < -ch/2) {
      agent.die = true
      continue
    }
    let d = map(agent.r, 0, min(cw, ch), 5, 30)
​
    if (agent.target) {
      let newAngle = agent.a + random(1, 2) * agent.dir
      // Ensure that the arcs are clockwise
      if (agent.dir === 1) {
        arc(0, 0, agent.r*2, agent.r*2, agent.a, newAngle)
      } else {
        arc(0, 0, agent.r*2, agent.r*2, newAngle, agent.a)
      }
      // If we've reached the target angle, reset it
      if (abs(newAngle - agent.target) < 1) {
        agent.target = null
      }
      agent.a = newAngle
    } else {
      if (random() < 0.2) {
        // Assign a new target and direction
        agent.dir = random([-1, 1])
        agent.target = agent.a + random(10, 30) * agent.dir
      } else {
        agent.r += d * random(0.8, 1.5)
        let nx = agent.r * cos(agent.a)
        let ny = agent.r * sin(agent.a)
        line(x, y, nx, ny)
      }
    }
    // Finally, there's a random chance that the agent will split into a new agent
    if (random() < 0.01) {
      agents.push({
        r: agent.r,
        a: agent.a,
        dir: agent.dir,
        color: random(0, 160)
      })
    }
  }
  // Remove agents that are out of bounds
  agents = agents.filter(agent => !agent.die)
}
​
function mousePressed() {
  background('#E2E2E2')
  agents = []
  for (let i = 0; i < 4; i++) {
    agents.push({
      r: 0,
      a: 90 * i,
      dir: 1,
      color: random(0, 160)
    })
  }
}