diff --git a/osu.Game/Rulesets/UI/Scrolling/Visualisers/OverlappingSpeedChangeVisualiser.cs b/osu.Game/Rulesets/UI/Scrolling/Visualisers/OverlappingSpeedChangeVisualiser.cs index 6045ab50e7..e45e391dbc 100644 --- a/osu.Game/Rulesets/UI/Scrolling/Visualisers/OverlappingSpeedChangeVisualiser.cs +++ b/osu.Game/Rulesets/UI/Scrolling/Visualisers/OverlappingSpeedChangeVisualiser.cs @@ -80,10 +80,12 @@ namespace osu.Game.Rulesets.UI.Scrolling.Visualisers } /// - /// Computes the position of a at a point in time.
+ /// Computes the position of a at a point in time. + /// /// At t < startTime, position > 0.
/// At t = startTime, position = 0.
/// At t > startTime, position < 0. + ///
///
/// The . /// The time to find the position of at. diff --git a/osu.Game/Rulesets/UI/Scrolling/Visualisers/SequentialSpeedChangeVisualiser.cs b/osu.Game/Rulesets/UI/Scrolling/Visualisers/SequentialSpeedChangeVisualiser.cs index 708a2f173b..c8725fab56 100644 --- a/osu.Game/Rulesets/UI/Scrolling/Visualisers/SequentialSpeedChangeVisualiser.cs +++ b/osu.Game/Rulesets/UI/Scrolling/Visualisers/SequentialSpeedChangeVisualiser.cs @@ -25,23 +25,25 @@ namespace osu.Game.Rulesets.UI.Scrolling.Visualisers { foreach (var obj in hitObjects) { + // To reduce iterations when updating hitobject positions later on, their initial positions are cached var startPosition = hitObjectPositions[obj] = positionAt(obj.HitObject.StartTime, timeRange); + // Todo: This is approximate and will be incorrect in the case of extreme speed changes obj.LifetimeStart = obj.HitObject.StartTime - timeRange - 1000; if (obj.HitObject is IHasEndTime endTime) { - var diff = positionAt(endTime.EndTime, timeRange) - startPosition; + var hitObjectLength = positionAt(endTime.EndTime, timeRange) - startPosition; switch (direction) { case ScrollingDirection.Up: case ScrollingDirection.Down: - obj.Height = (float)(diff * length.Y); + obj.Height = (float)(hitObjectLength * length.Y); break; case ScrollingDirection.Left: case ScrollingDirection.Right: - obj.Width = (float)(diff * length.X); + obj.Width = (float)(hitObjectLength * length.X); break; } } @@ -49,6 +51,8 @@ namespace osu.Game.Rulesets.UI.Scrolling.Visualisers if (obj.HasNestedHitObjects) { ComputeInitialStates(obj.NestedHitObjects, direction, timeRange, length); + + // Nested hitobjects don't need to scroll, but they do need accurate positions ComputePositions(obj.NestedHitObjects, direction, obj.HitObject.StartTime, timeRange, length); } } @@ -80,21 +84,38 @@ namespace osu.Game.Rulesets.UI.Scrolling.Visualisers } } + /// + /// Finds the position which corresponds to a point in time. + /// This is a non-linear operation that depends on all the control points up to and including the one active at the time value. + /// + /// The time to find the position at. + /// The amount of time visualised by the scrolling area. + /// A positive value indicating the position at . private double positionAt(double time, double timeRange) { double length = 0; + + // We need to consider all timing points until the specified time and not just the currently-active one, + // since each timing point individually affects the positions of _all_ hitobjects after its start time for (int i = 0; i < controlPoints.Count; i++) { var current = controlPoints[i]; var next = i < controlPoints.Count - 1 ? controlPoints[i + 1] : null; + // We don't need to consider any control points beyond the current time, since it will not yet + // affect any hitobjects if (i > 0 && current.StartTime > time) continue; // Duration of the current control point var currentDuration = (next?.StartTime ?? double.PositiveInfinity) - current.StartTime; - length += Math.Min(currentDuration, time - current.StartTime) * current.Multiplier / timeRange; + // We want to consider the minimal amount of time that this control point has affected, + // which may be either its duration, or the amount of time that has passed within it + var durationInCurrent = Math.Min(currentDuration, time - current.StartTime); + + // Figure out how much of the time range the duration represents, and adjust it by the speed multiplier + length += durationInCurrent / timeRange * current.Multiplier; } return length;