Starfield

defmodule PhxDemo.Examples.Starfield do
  def render do
    :rand.seed(:exsss, {100, 200, 300})
    width = 600
    height = 400

    canvas =
      Easel.new(width, height)
      |> Easel.set_fill_style("#0a0a2e")
      |> Easel.fill_rect(0, 0, width, height)

    canvas =
      Enum.reduce(1..200, canvas, fn _, acc ->
        x = :rand.uniform(width)
        y = :rand.uniform(height)
        radius = :rand.uniform() * 2.5 + 0.5
        brightness = :rand.uniform(155) + 100

        color =
          "rgba(#{brightness}, #{brightness}, #{min(255, brightness + 50)}, #{Float.round(:rand.uniform(), 2)})"

        acc
        |> Easel.begin_path()
        |> Easel.arc(x, y, radius, 0, :math.pi() * 2)
        |> Easel.set_fill_style(color)
        |> Easel.fill()
      end)

    Enum.reduce(1..8, canvas, fn _, acc ->
      x = :rand.uniform(width)
      y = :rand.uniform(height)

      acc
      |> Easel.save()
      |> Easel.set_global_alpha(0.3)
      |> Easel.begin_path()
      |> Easel.arc(x, y, 8, 0, :math.pi() * 2)
      |> Easel.set_fill_style("rgba(200, 200, 255, 0.3)")
      |> Easel.fill()
      |> Easel.set_global_alpha(1.0)
      |> Easel.begin_path()
      |> Easel.arc(x, y, 2, 0, :math.pi() * 2)
      |> Easel.set_fill_style("white")
      |> Easel.fill()
      |> Easel.restore()
    end)
    |> Easel.render()
  end
end