Sinusoidal property

Implementation

static Map<ETTypes,num Function(num,[num?])> Sinusoidal = {
  ETTypes.In:(amount,[power]) {
    return 1 - math.sin(((1.0 - amount) * math.pi) / 2);
  },
  ETTypes.Out:(amount,[power]) {
    return math.sin((amount * math.pi) / 2);
  },
  ETTypes.InOut:(amount,[power]) {
    return 0.5 * (1 - math.sin(math.pi * (0.5 - amount)));
  },
};