Catmull-Rom Spline in GDScript

catmull-rom.gd

func catmull_rom_spline(
	_points: Array, resolution: int = 10, extrapolate_end_points = true
) -> PackedVector2Array:
  var points = _points.duplicate()
  if extrapolate_end_points:
    points.insert(0, points[0] - (points[1] - points[0]))
    points.append(points[-1] + (points[-1] - points[-2]))

  var smooth_points := PackedVector2Array()
  if points.size() < 4:
    return points

  for i in range(1, points.size() - 2):
    var p0 = points[i - 1]
    var p1 = points[i]
    var p2 = points[i + 1]
    var p3 = points[i + 2]

    for t in range(0, resolution):
      var tt = t / float(resolution)
      var tt2 = tt * tt
      var tt3 = tt2 * tt

      var q = (
        0.5
        * (
          (2.0 * p1)
          + (-p0 + p2) * tt
          + (2.0 * p0 - 5.0 * p1 + 4 * p2 - p3) * tt2
          + (-p0 + 3.0 * p1 - 3.0 * p2 + p3) * tt3
        )
      )

      smooth_points.append(q)

  return smooth_points