From 85c42456f25c9a27cd4871fb2cc71e1e3caf1b17 Mon Sep 17 00:00:00 2001 From: smoogipoo Date: Tue, 30 Jun 2020 21:38:51 +0900 Subject: [PATCH] Improve performance of sequential scrolling algorithm --- .../Algorithms/SequentialScrollAlgorithm.cs | 164 +++++++++++------- 1 file changed, 104 insertions(+), 60 deletions(-) diff --git a/osu.Game/Rulesets/UI/Scrolling/Algorithms/SequentialScrollAlgorithm.cs b/osu.Game/Rulesets/UI/Scrolling/Algorithms/SequentialScrollAlgorithm.cs index 0052c877f6..a1f68d7201 100644 --- a/osu.Game/Rulesets/UI/Scrolling/Algorithms/SequentialScrollAlgorithm.cs +++ b/osu.Game/Rulesets/UI/Scrolling/Algorithms/SequentialScrollAlgorithm.cs @@ -3,21 +3,26 @@ using System; using System.Collections.Generic; +using System.Diagnostics; +using JetBrains.Annotations; using osu.Game.Rulesets.Timing; namespace osu.Game.Rulesets.UI.Scrolling.Algorithms { public class SequentialScrollAlgorithm : IScrollAlgorithm { - private readonly Dictionary positionCache; + private static readonly IComparer by_position_comparer = Comparer.Create((c1, c2) => c1.Position.CompareTo(c2.Position)); private readonly IReadOnlyList controlPoints; + /// + /// Stores a mapping of time -> position for each control point. + /// + private readonly List positionMappings = new List(); + public SequentialScrollAlgorithm(IReadOnlyList controlPoints) { this.controlPoints = controlPoints; - - positionCache = new Dictionary(); } public double GetDisplayStartTime(double originTime, float offset, double timeRange, float scrollLength) @@ -27,55 +32,31 @@ namespace osu.Game.Rulesets.UI.Scrolling.Algorithms public float GetLength(double startTime, double endTime, double timeRange, float scrollLength) { - var objectLength = relativePositionAtCached(endTime, timeRange) - relativePositionAtCached(startTime, timeRange); + var objectLength = relativePositionAt(endTime, timeRange) - relativePositionAt(startTime, timeRange); return (float)(objectLength * scrollLength); } public float PositionAt(double time, double currentTime, double timeRange, float scrollLength) { - // Caching is not used here as currentTime is unlikely to have been previously cached - double timelinePosition = relativePositionAt(currentTime, timeRange); - return (float)((relativePositionAtCached(time, timeRange) - timelinePosition) * scrollLength); + double timelineLength = relativePositionAt(time, timeRange) - relativePositionAt(currentTime, timeRange); + return (float)(timelineLength * scrollLength); } public double TimeAt(float position, double currentTime, double timeRange, float scrollLength) { - // Convert the position to a length relative to time = 0 - double length = position / scrollLength + relativePositionAt(currentTime, timeRange); + if (controlPoints.Count == 0) + return position * timeRange; - // 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; + // Find the position at the current time, and the given length. + double relativePosition = relativePositionAt(currentTime, timeRange) + position / scrollLength; - // Duration of the current control point - var currentDuration = (next?.StartTime ?? double.PositiveInfinity) - current.StartTime; + var positionMapping = findControlPointMapping(timeRange, new PositionMapping(0, null, relativePosition), by_position_comparer); - // Figure out the length of control point - var currentLength = currentDuration / timeRange * current.Multiplier; - - if (currentLength > length) - { - // The point is within this control point - return current.StartTime + length * timeRange / current.Multiplier; - } - - length -= currentLength; - } - - return 0; // Should never occur + // Begin at the control point's time and add the remaining time to reach the given position. + return positionMapping.Time + (relativePosition - positionMapping.Position) * timeRange / positionMapping.ControlPoint.Multiplier; } - private double relativePositionAtCached(double time, double timeRange) - { - if (!positionCache.TryGetValue(time, out double existing)) - positionCache[time] = existing = relativePositionAt(time, timeRange); - return existing; - } - - public void Reset() => positionCache.Clear(); + public void Reset() => positionMappings.Clear(); /// /// Finds the position which corresponds to a point in time. @@ -84,37 +65,100 @@ namespace osu.Game.Rulesets.UI.Scrolling.Algorithms /// 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 relativePositionAt(double time, double timeRange) + private double relativePositionAt(in double time, in double timeRange) { if (controlPoints.Count == 0) return time / timeRange; - double length = 0; + var mapping = findControlPointMapping(timeRange, new PositionMapping(time)); - // 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++) + // Begin at the control point's position and add the remaining distance to reach the given time. + return mapping.Position + (time - mapping.Time) / timeRange * mapping.ControlPoint.Multiplier; + } + + /// + /// Finds a 's that is relevant to a given . + /// + /// + /// This is used to find the last occuring prior to a time value, or prior to a position value (if is used). + /// + /// The time range. + /// The to find the closest to. + /// The comparison. If null, the default comparer is used (by time). + /// The 's that is relevant for . + private PositionMapping findControlPointMapping(in double timeRange, in PositionMapping search, IComparer comparer = null) + { + generatePositionMappings(timeRange); + + var mappingIndex = positionMappings.BinarySearch(search, comparer ?? Comparer.Default); + + if (mappingIndex < 0) { - var current = controlPoints[i]; - var next = i < controlPoints.Count - 1 ? controlPoints[i + 1] : null; + // If the search value isn't found, the _next_ control point is returned, but we actually want the _previous_ control point. + // In doing so, we must make sure to not underflow the position mapping list (i.e. always use the 0th control point for time < first_control_point_time). + mappingIndex = Math.Max(0, ~mappingIndex - 1); - // 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; - - // 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; + Debug.Assert(mappingIndex < positionMappings.Count); } - return length; + var mapping = positionMappings[mappingIndex]; + Debug.Assert(mapping.ControlPoint != null); + + return mapping; + } + + /// + /// Generates the mapping of (and their respective start times) to their relative position from 0. + /// + /// The time range. + private void generatePositionMappings(in double timeRange) + { + if (positionMappings.Count > 0) + return; + + if (controlPoints.Count == 0) + return; + + positionMappings.Add(new PositionMapping(controlPoints[0].StartTime, controlPoints[0])); + + for (int i = 0; i < controlPoints.Count - 1; i++) + { + var current = controlPoints[i]; + var next = controlPoints[i + 1]; + + // Figure out how much of the time range the duration represents, and adjust it by the speed multiplier + float length = (float)((next.StartTime - current.StartTime) / timeRange * current.Multiplier); + + positionMappings.Add(new PositionMapping(next.StartTime, next, positionMappings[^1].Position + length)); + } + } + + private readonly struct PositionMapping : IComparable + { + /// + /// The time corresponding to this position. + /// + public readonly double Time; + + /// + /// The at . + /// + [CanBeNull] + public readonly MultiplierControlPoint ControlPoint; + + /// + /// The relative position from 0 of . + /// + public readonly double Position; + + public PositionMapping(double time, MultiplierControlPoint controlPoint = null, double position = default) + { + Time = time; + ControlPoint = controlPoint; + Position = position; + } + + public int CompareTo(PositionMapping other) => Time.CompareTo(other.Time); } } }