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118 lines
5.2 KiB
C#
118 lines
5.2 KiB
C#
// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
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// See the LICENCE file in the repository root for full licence text.
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using System;
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using System.Collections.Generic;
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using osu.Game.Rulesets.Timing;
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namespace osu.Game.Rulesets.UI.Scrolling.Algorithms
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{
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public class SequentialScrollAlgorithm : IScrollAlgorithm
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{
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private readonly Dictionary<double, double> positionCache;
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private readonly IReadOnlyList<MultiplierControlPoint> controlPoints;
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public SequentialScrollAlgorithm(IReadOnlyList<MultiplierControlPoint> controlPoints)
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{
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this.controlPoints = controlPoints;
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positionCache = new Dictionary<double, double>();
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}
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public double GetDisplayStartTime(double time, double timeRange) => time - timeRange - 1000;
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public float GetLength(double startTime, double endTime, double timeRange, float scrollLength)
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{
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var objectLength = relativePositionAtCached(endTime, timeRange) - relativePositionAtCached(startTime, timeRange);
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return (float)(objectLength * scrollLength);
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}
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public float PositionAt(double time, double currentTime, double timeRange, float scrollLength)
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{
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// Caching is not used here as currentTime is unlikely to have been previously cached
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double timelinePosition = relativePositionAt(currentTime, timeRange);
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return (float)((relativePositionAtCached(time, timeRange) - timelinePosition) * scrollLength);
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}
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public double TimeAt(float position, double currentTime, double timeRange, float scrollLength)
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{
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// Convert the position to a length relative to time = 0
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double length = position / scrollLength + relativePositionAt(currentTime, timeRange);
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// We need to consider all timing points until the specified time and not just the currently-active one,
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// since each timing point individually affects the positions of _all_ hitobjects after its start time
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for (int i = 0; i < controlPoints.Count; i++)
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{
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var current = controlPoints[i];
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var next = i < controlPoints.Count - 1 ? controlPoints[i + 1] : null;
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// Duration of the current control point
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var currentDuration = (next?.StartTime ?? double.PositiveInfinity) - current.StartTime;
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// Figure out the length of control point
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var currentLength = currentDuration / timeRange * current.Multiplier;
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if (currentLength > length)
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{
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// The point is within this control point
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return current.StartTime + length * timeRange / current.Multiplier;
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}
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length -= currentLength;
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}
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return 0; // Should never occur
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}
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private double relativePositionAtCached(double time, double timeRange)
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{
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if (!positionCache.TryGetValue(time, out double existing))
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positionCache[time] = existing = relativePositionAt(time, timeRange);
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return existing;
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}
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public void Reset() => positionCache.Clear();
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/// <summary>
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/// Finds the position which corresponds to a point in time.
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/// This is a non-linear operation that depends on all the control points up to and including the one active at the time value.
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/// </summary>
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/// <param name="time">The time to find the position at.</param>
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/// <param name="timeRange">The amount of time visualised by the scrolling area.</param>
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/// <returns>A positive value indicating the position at <paramref name="time"/>.</returns>
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private double relativePositionAt(double time, double timeRange)
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{
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if (controlPoints.Count == 0)
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return time / timeRange;
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double length = 0;
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// We need to consider all timing points until the specified time and not just the currently-active one,
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// since each timing point individually affects the positions of _all_ hitobjects after its start time
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for (int i = 0; i < controlPoints.Count; i++)
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{
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var current = controlPoints[i];
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var next = i < controlPoints.Count - 1 ? controlPoints[i + 1] : null;
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// We don't need to consider any control points beyond the current time, since it will not yet
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// affect any hitobjects
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if (i > 0 && current.StartTime > time)
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continue;
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// Duration of the current control point
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var currentDuration = (next?.StartTime ?? double.PositiveInfinity) - current.StartTime;
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// We want to consider the minimal amount of time that this control point has affected,
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// which may be either its duration, or the amount of time that has passed within it
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var durationInCurrent = Math.Min(currentDuration, time - current.StartTime);
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// Figure out how much of the time range the duration represents, and adjust it by the speed multiplier
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length += durationInCurrent / timeRange * current.Multiplier;
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}
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return length;
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}
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}
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}
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