public double CalculateDifficulty(DifficultyType type)
{
var highestStrains = new List <double>();
var intervalEndTime = STRAIN_STEP * _modSpeed;
double maximumStrain = 0;
TpHitObject previousHitObject = null;
foreach (var hitObject in TpHitObjects)
{
while (hitObject.BaseHitObject.StartTime > intervalEndTime)
{
highestStrains.Add(maximumStrain);
if (previousHitObject == null)
{
maximumStrain = 0;
}
else
{
var decay = Math.Pow(TpHitObject.DECAY_BASE[(int)type], (intervalEndTime - previousHitObject.BaseHitObject.StartTime) / 1000);
maximumStrain = previousHitObject.Strains[(int)type] * decay;
}
intervalEndTime += STRAIN_STEP;
}
if (hitObject.Strains[(int)type] > maximumStrain)
{
maximumStrain = hitObject.Strains[(int)type];
}
previousHitObject = hitObject;
}
double difficulty = 0;
double weight = 1;
highestStrains.Sort((a, b) => b.CompareTo(a));
foreach (var strain in highestStrains)
{
difficulty += weight * strain;
weight *= DECAY_WEIGHT;
}
return(difficulty);
}
private void CalculateSpecificStrain(TpHitObject previousHitObject, DifficultyType type, double speedMultiplier)
{
double addition = 0;
var timeElapsed = (BaseHitObject.StartTime - previousHitObject.BaseHitObject.StartTime) * speedMultiplier;
var decay = Math.Pow(DECAY_BASE[(int)type], timeElapsed / 1000);
switch (BaseHitObject.Type)
{
case HitObjectType.Slider:
switch (type)
{
case DifficultyType.Speed:
addition =
SpacingWeight(previousHitObject._lazySliderLengthFirst +
previousHitObject._lazySliderLengthSubsequent * ((previousHitObject.BaseHitObject).SegmentCount - 1) +
DistanceTo(previousHitObject), type) *
SPACING_WEIGHT_SCALING[(int)type];
break;
case DifficultyType.Aim:
addition =
(
SpacingWeight(previousHitObject._lazySliderLengthFirst, type) +
SpacingWeight(previousHitObject._lazySliderLengthSubsequent, type) * ((previousHitObject.BaseHitObject).SegmentCount - 1) +
SpacingWeight(DistanceTo(previousHitObject), type)
) *
SPACING_WEIGHT_SCALING[(int)type];
break;
}
break;
case HitObjectType.HitCircle:
addition = SpacingWeight(DistanceTo(previousHitObject), type) * SPACING_WEIGHT_SCALING[(int)type];
break;
}
addition /= Math.Max(timeElapsed, 50);
Strains[(int)type] = previousHitObject.Strains[(int)type] * decay + addition;
}
public double DistanceTo(TpHitObject other) => _normalizedStartPosition.Distance(other._normalizedEndPosition);
public void CalculateStrains(TpHitObject previousHitObject, double speedMultiplier)
{
CalculateSpecificStrain(previousHitObject, DifficultyType.Speed, speedMultiplier);
CalculateSpecificStrain(previousHitObject, DifficultyType.Aim, speedMultiplier);
}