Back property

Map<ETTypes, num Function(num, [num?])> Back
getter/setter pair

Implementation

static Map<ETTypes,num Function(num,[num?])> Back = {
  ETTypes.In:(amount,[power]) {
    var s = 1.70158;
    return amount == 1 ? 1 : amount * amount * ((s + 1) * amount - s);
  },
  ETTypes.Out:(amount,[power]) {
    var s = 1.70158;
    return amount == 0 ? 0 : --amount * amount * ((s + 1) * amount + s) + 1;
  },
  ETTypes.InOut:(amount,[power]) {
    var s = 1.70158 * 1.525;
    if ((amount *= 2) < 1) {
      return 0.5 * (amount * amount * ((s + 1) * amount - s));
    }
    return 0.5 * ((amount -= 2) * amount * ((s + 1) * amount + s) + 2);
  },
};