Comment by minitech

Scroll down:

  u(t) is called 60 times per second.
  t: elapsed time in seconds.
  c: A 1920x1080 canvas.
  x: A 2D context for that canvas.
  S: Math.sin
  C: Math.cos
  T: Math.tan
  R: Generates rgba-strings, ex.: R(255, 255, 255, 0.5)