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CoffeeScript Ikeda Map

  1. canvas = document.querySelector "canvas"
  2. c = canvas.getContext "2d"
  3. locX = 120
  4. locY = 400
  5. xn1 = xn = yn1 = yn = tn = 0
  6. u = .7
  7. steps = 10
  8. iterations = 200
  9. scale = 180
  10.  
  11. c.fillStyle = "black"
  12. c.fillRect 0, 0, canvas.width, canvas.height
  13. c.fillStyle = "rgba(255,255,255,0.2)"
  14.  
  15. run = setInterval ->
  16.   clearInterval run if u > 1
  17.   i = 0
  18.  
  19.   while i < steps
  20.     u += 0.00015
  21.     j = 0
  22.  
  23.     while j < iterations
  24.       xn = xn1
  25.       yn = yn1
  26.       tn = 0.4 - (6 / (1 + xn * xn + yn * yn))
  27.       xn1 = 1 + u * (xn * Math.cos(tn) - yn * Math.sin tn)
  28.       yn1 = u * (xn * Math.sin(tn) + yn * Math.cos tn)
  29.       c.fillRect locX + xn1 * scale, locY + yn1 * scale, 1, 1
  30.       j++
  31.     i++
  32. , 30

I do quite miss CoffeeScript sometimes… here is an old codepen of the Ikeda Map:

See the Pen Ikeda Map by Zevan Rosser (@ZevanRosser) on CodePen.

snippet.zone ~ 2021-22 /// {s/z}