const radius = 1.5

const minDist = 15

const maxDist = 40

​

const minDistance2 = minDist ** 2

const maxDistance2 = maxDist ** 2

​

const dim = 400

​

const particles = []

​

function setup() {

  createCanvas(dim, dim)

​

  for (let i = 0; i < n; ++i) {

    particles[i] = {

      x: Math.random() * dim,

      y: Math.random() * dim,

      vx: 0,

      vy: 0,

    }

  }

}

​

function draw() {

  background('#222')

   fill('white')

​

  for (let i = 0; i < n; ++i) {

    const p = particles[i]

    p.x += p.vx

    if (p.x < -maxDist) p.x += width + maxDist * 2

    else if (p.x > width + maxDist) p.x -= width + maxDist * 2

    p.y += p.vy

    if (p.y < -maxDist) p.y += height + maxDist * 2

    else if (p.y > height + maxDist) p.y -= height + maxDist * 2

    p.vx += 0.2 * (Math.random() - 0.5) - 0.01 * p.vx

    p.vy += 0.2 * (Math.random() - 0.5) - 0.01 * p.vy

​

    circle(p.x, p.y, radius * 2)

  }

​

  for (let i = 0; i < n; ++i) {

    for (let j = i + 1; j < n; ++j) {

      const pi = particles[i]

      const pj = particles[j]

      const dx = pi.x - pj.x

      const dy = pi.y - pj.y

      const d2 = dx * dx + dy * dy

      if (d2 < maxDistance2) {

        const alpha

          = d2 > minDistance2 ? (maxDistance2 - d2) / (maxDistance2 - minDistance2) : 1

        if (isDark.value)

          stroke(255, lerp(0, 255, alpha))

​

        else

          stroke(0, lerp(0, 255, alpha))

​

        line(pi.x, pi.y, pj.x, pj.y)

      }

    }

  }

}