private double calculateDifficulty(List <CatchDifficultyHitObject> objects, double timeRate)
{
// The strain step needs to be adjusted for the algorithm to be considered equal with speed changing mods
double actualStrainStep = strain_step * timeRate;
// Find the highest strain value within each strain step
var highestStrains = new List <double>();
double intervalEndTime = actualStrainStep;
double maximumStrain = 0; // We need to keep track of the maximum strain in the current interval
CatchDifficultyHitObject previousHitObject = null;
foreach (CatchDifficultyHitObject hitObject in objects)
{
// While we are beyond the current interval push the currently available maximum to our strain list
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(CatchDifficultyHitObject.DECAY_BASE, (intervalEndTime - previousHitObject.BaseHitObject.StartTime) / 1000);
maximumStrain = previousHitObject.Strain * decay;
}
// Go to the next time interval
intervalEndTime += actualStrainStep;
}
// Obtain maximum strain
maximumStrain = Math.Max(hitObject.Strain, 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);
}
private bool calculateStrainValues(List <CatchDifficultyHitObject> objects, double timeRate)
{
CatchDifficultyHitObject lastObject = null;
if (!objects.Any())
{
return(false);
}
// Traverse hitObjects in pairs to calculate the strain value of NextHitObject from the strain value of CurrentHitObject and environment.
foreach (var currentObject in objects)
{
if (lastObject != null)
{
currentObject.CalculateStrains(lastObject, timeRate);
}
lastObject = currentObject;
}
return(true);
}
internal void CalculateStrains(CatchDifficultyHitObject previousHitObject, double timeRate)
{
// Rather simple, but more specialized things are inherently inaccurate due to the big difference playstyles and opinions make.
// See Taiko feedback thread.
double timeElapsed = (BaseHitObject.StartTime - previousHitObject.BaseHitObject.StartTime) / timeRate;
double decay = Math.Pow(DECAY_BASE, timeElapsed / 1000);
// Update new position with lazy movement.
PlayerPositionOffset =
MathHelper.Clamp(
previousHitObject.ActualNormalizedPosition,
NormalizedPosition - (normalized_hitobject_radius - playerPositioningError),
NormalizedPosition + (normalized_hitobject_radius - playerPositioningError)) // Obtain new lazy position, but be stricter by allowing for an error of a certain degree of the player.
- NormalizedPosition; // Subtract HitObject position to obtain offset
LastMovement = DistanceTo(previousHitObject);
double addition = spacingWeight(LastMovement);
if (NormalizedPosition < previousHitObject.NormalizedPosition)
{
LastMovement = -LastMovement;
}
CatchHitObject previousHitCircle = previousHitObject.BaseHitObject;
double additionBonus = 0;
double sqrtTime = Math.Sqrt(Math.Max(timeElapsed, 25));
// Direction changes give an extra point!
if (Math.Abs(LastMovement) > 0.1)
{
if (Math.Abs(previousHitObject.LastMovement) > 0.1 && Math.Sign(LastMovement) != Math.Sign(previousHitObject.LastMovement))
{
double bonus = direction_change_bonus / sqrtTime;
// Weight bonus by how
double bonusFactor = Math.Min(playerPositioningError, Math.Abs(LastMovement)) / playerPositioningError;
// We want time to play a role twice here!
addition += bonus * bonusFactor;
// Bonus for tougher direction switches and "almost" hyperdashes at this point
if (previousHitCircle != null && previousHitCircle.DistanceToHyperDash <= 10.0f / CatchPlayfield.BASE_WIDTH)
{
additionBonus += 0.3 * bonusFactor;
}
}
// Base bonus for every movement, giving some weight to streams.
addition += 7.5 * Math.Min(Math.Abs(LastMovement), normalized_hitobject_radius * 2) / (normalized_hitobject_radius * 6) / sqrtTime;
}
// Bonus for "almost" hyperdashes at corner points
if (previousHitCircle != null && previousHitCircle.DistanceToHyperDash <= 10.0f / CatchPlayfield.BASE_WIDTH)
{
if (!previousHitCircle.HyperDash)
{
additionBonus += 1.0;
}
else
{
// After a hyperdash we ARE in the correct position. Always!
PlayerPositionOffset = 0;
}
addition *= 1.0 + additionBonus * ((10 - previousHitCircle.DistanceToHyperDash * CatchPlayfield.BASE_WIDTH) / 10);
}
addition *= 850.0 / Math.Max(timeElapsed, 25);
Strain = previousHitObject.Strain * decay + addition;
}
internal float DistanceTo(CatchDifficultyHitObject other)
{
return(Math.Abs(ActualNormalizedPosition - other.ActualNormalizedPosition));
}