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Code Issues Releases Wiki Activity

Improve performance of sequential scrolling algorithm

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smoogipoo 2020-06-30 21:38:51 +09:00
parent 50ae69b111
commit 85c42456f2
1 changed files with 104 additions and 60 deletions
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164
osu.Game/Rulesets/UI/Scrolling/Algorithms/SequentialScrollAlgorithm.cs
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@ -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<double, double> positionCache;
private static readonly IComparer<PositionMapping> by_position_comparer = Comparer<PositionMapping>.Create((c1, c2) => c1.Position.CompareTo(c2.Position));
private readonly IReadOnlyList<MultiplierControlPoint> controlPoints;
/// <summary>
/// Stores a mapping of time -> position for each control point.
/// </summary>
private readonly List<PositionMapping> positionMappings = new List<PositionMapping>();
public SequentialScrollAlgorithm(IReadOnlyList<MultiplierControlPoint> controlPoints)
{
this.controlPoints = controlPoints;
positionCache = new Dictionary<double, double>();
}
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();
/// <summary>
/// Finds the position which corresponds to a point in time.
@ -84,37 +65,100 @@ namespace osu.Game.Rulesets.UI.Scrolling.Algorithms
/// <param name="time">The time to find the position at.</param>
/// <param name="timeRange">The amount of time visualised by the scrolling area.</param>
/// <returns>A positive value indicating the position at <paramref name="time"/>.</returns>
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;
}
/// <summary>
/// Finds a <see cref="MultiplierControlPoint"/>'s <see cref="PositionMapping"/> that is relevant to a given <see cref="PositionMapping"/>.
/// </summary>
/// <remarks>
/// This is used to find the last <see cref="MultiplierControlPoint"/> occuring prior to a time value, or prior to a position value (if <see cref="by_position_comparer"/> is used).
/// </remarks>
/// <param name="timeRange">The time range.</param>
/// <param name="search">The <see cref="PositionMapping"/> to find the closest <see cref="PositionMapping"/> to.</param>
/// <param name="comparer">The comparison. If null, the default comparer is used (by time).</param>
/// <returns>The <see cref="MultiplierControlPoint"/>'s <see cref="PositionMapping"/> that is relevant for <paramref name="search"/>.</returns>
private PositionMapping findControlPointMapping(in double timeRange, in PositionMapping search, IComparer<PositionMapping> comparer = null)
{
generatePositionMappings(timeRange);
var mappingIndex = positionMappings.BinarySearch(search, comparer ?? Comparer<PositionMapping>.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;
}
/// <summary>
/// Generates the mapping of <see cref="MultiplierControlPoint"/> (and their respective start times) to their relative position from 0.
/// </summary>
/// <param name="timeRange">The time range.</param>
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<PositionMapping>
{
/// <summary>
/// The time corresponding to this position.
/// </summary>
public readonly double Time;
/// <summary>
/// The <see cref="MultiplierControlPoint"/> at <see cref="Time"/>.
/// </summary>
[CanBeNull]
public readonly MultiplierControlPoint ControlPoint;
/// <summary>
/// The relative position from 0 of <see cref="ControlPoint"/>.
/// </summary>
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);
}
}
}