protected double CalculateDifficulty(DifficultyType type)
{
double actualStrainStep = STRAIN_STEP * TimeRate;
List <double> highestStrains = new List <double>();
double intervalEndTime = actualStrainStep;
double maximumStrain = 0;
VitaruHitObjectDifficulty previousHitObject = null;
foreach (VitaruHitObjectDifficulty hitObject in DifficultyHitObjects)
{
while (hitObject.BaseHitObject.StartTime > intervalEndTime)
{
highestStrains.Add(maximumStrain);
// The maximum strain of the next interval is not zero by default! We need to take the last hitObject we encountered, take its strain and apply the decay
// until the beginning of the next interval.
if (previousHitObject == null)
{
maximumStrain = 0;
}
else
{
double decay = Math.Pow(VitaruHitObjectDifficulty.DECAY_BASE[(int)type], (intervalEndTime - previousHitObject.BaseHitObject.StartTime) / 1000);
maximumStrain = previousHitObject.Strains[(int)type] * decay;
}
// Go to the next time interval
intervalEndTime += actualStrainStep;
}
// Obtain maximum strain
maximumStrain = Math.Max(hitObject.Strains[(int)type], maximumStrain);
previousHitObject = hitObject;
}
// Build the weighted sum over the highest strains for each interval
double difficulty = 0;
double weight = 1;
highestStrains.Sort((a, b) => b.CompareTo(a)); // Sort from highest to lowest strain.
foreach (double strain in highestStrains)
{
difficulty += weight * strain;
weight *= DECAY_WEIGHT;
}
return(difficulty);
}
protected bool CalculateStrainValues()
{
// Traverse hitObjects in pairs to calculate the strain value of NextHitObject from the strain value of CurrentHitObject and environment.
using (List <VitaruHitObjectDifficulty> .Enumerator hitObjectsEnumerator = DifficultyHitObjects.GetEnumerator())
{
if (!hitObjectsEnumerator.MoveNext())
{
return(false);
}
VitaruHitObjectDifficulty current = hitObjectsEnumerator.Current;
// First hitObject starts at strain 1. 1 is the default for strain values, so we don't need to set it here. See DifficultyHitObject.
while (hitObjectsEnumerator.MoveNext())
{
var next = hitObjectsEnumerator.Current;
next?.CalculateStrains(current, TimeRate);
current = next;
}
return(true);
}
}
