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510 lines
20 KiB
C#
510 lines
20 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 System.Collections.Specialized;
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using System.Diagnostics;
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using System.Linq;
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using Newtonsoft.Json;
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using osu.Framework.Bindables;
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using osu.Framework.Caching;
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using osu.Framework.Utils;
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using osu.Game.Rulesets.Objects.Types;
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using osuTK;
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namespace osu.Game.Rulesets.Objects
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{
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public class SliderPath
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{
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/// <summary>
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/// The current version of this <see cref="SliderPath"/>. Updated when any change to the path occurs.
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/// </summary>
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[JsonIgnore]
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public IBindable<int> Version => version;
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private readonly Bindable<int> version = new Bindable<int>();
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/// <summary>
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/// The user-set distance of the path. If non-null, <see cref="Distance"/> will match this value,
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/// and the path will be shortened/lengthened to match this length.
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/// </summary>
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public readonly Bindable<double?> ExpectedDistance = new Bindable<double?>();
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public bool HasValidLength => Precision.DefinitelyBigger(Distance, 0);
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/// <summary>
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/// The control points of the path.
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/// </summary>
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public readonly BindableList<PathControlPoint> ControlPoints = new BindableList<PathControlPoint>();
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private readonly List<Vector2> calculatedPath = new List<Vector2>();
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private readonly List<double> cumulativeLength = new List<double>();
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private readonly Cached pathCache = new Cached();
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/// <summary>
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/// Any additional length of the path which was optimised out during piecewise approximation, but should still be considered as part of <see cref="calculatedLength"/>.
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/// </summary>
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/// <remarks>
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/// This is a hack for Catmull paths.
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/// </remarks>
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private double optimisedLength;
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/// <summary>
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/// The final calculated length of the path.
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/// </summary>
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private double calculatedLength;
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private readonly List<int> segmentEnds = new List<int>();
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private double[] segmentEndDistances = Array.Empty<double>();
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/// <summary>
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/// Creates a new <see cref="SliderPath"/>.
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/// </summary>
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public SliderPath()
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{
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ExpectedDistance.ValueChanged += _ => invalidate();
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ControlPoints.CollectionChanged += (_, args) =>
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{
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switch (args.Action)
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{
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case NotifyCollectionChangedAction.Add:
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Debug.Assert(args.NewItems != null);
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foreach (object? newItem in args.NewItems)
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((PathControlPoint)newItem).Changed += invalidate;
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break;
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case NotifyCollectionChangedAction.Reset:
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case NotifyCollectionChangedAction.Remove:
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Debug.Assert(args.OldItems != null);
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foreach (object? oldItem in args.OldItems)
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((PathControlPoint)oldItem).Changed -= invalidate;
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break;
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}
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invalidate();
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};
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}
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/// <summary>
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/// Creates a new <see cref="SliderPath"/> initialised with a list of control points.
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/// </summary>
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/// <param name="controlPoints">An optional set of <see cref="PathControlPoint"/>s to initialise the path with.</param>
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/// <param name="expectedDistance">A user-set distance of the path that may be shorter or longer than the true distance between all control points.
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/// The path will be shortened/lengthened to match this length. If null, the path will use the true distance between all control points.</param>
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[JsonConstructor]
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public SliderPath(PathControlPoint[] controlPoints, double? expectedDistance = null)
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: this()
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{
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ControlPoints.AddRange(controlPoints);
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ExpectedDistance.Value = expectedDistance;
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}
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public SliderPath(PathType type, Vector2[] controlPoints, double? expectedDistance = null)
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: this(controlPoints.Select((c, i) => new PathControlPoint(c, i == 0 ? type : null)).ToArray(), expectedDistance)
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{
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}
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/// <summary>
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/// The distance of the path after lengthening/shortening to account for <see cref="ExpectedDistance"/>.
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/// </summary>
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[JsonIgnore]
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public double Distance
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{
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get
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{
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ensureValid();
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return cumulativeLength.Count == 0 ? 0 : cumulativeLength[^1];
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}
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}
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/// <summary>
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/// The distance of the path prior to lengthening/shortening to account for <see cref="ExpectedDistance"/>.
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/// </summary>
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public double CalculatedDistance
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{
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get
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{
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ensureValid();
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return calculatedLength;
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}
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}
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private bool optimiseCatmull;
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/// <summary>
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/// Whether to optimise Catmull path segments, usually resulting in removing bulbs around stacked knots.
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/// </summary>
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/// <remarks>
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/// This changes the path shape and should therefore not be used.
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/// </remarks>
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public bool OptimiseCatmull
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{
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get => optimiseCatmull;
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set
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{
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optimiseCatmull = value;
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invalidate();
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}
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}
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/// <summary>
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/// Computes the slider path until a given progress that ranges from 0 (beginning of the slider)
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/// to 1 (end of the slider) and stores the generated path in the given list.
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/// </summary>
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/// <param name="path">The list to be filled with the computed path.</param>
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/// <param name="p0">Start progress. Ranges from 0 (beginning of the slider) to 1 (end of the slider).</param>
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/// <param name="p1">End progress. Ranges from 0 (beginning of the slider) to 1 (end of the slider).</param>
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public void GetPathToProgress(List<Vector2> path, double p0, double p1)
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{
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ensureValid();
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double d0 = progressToDistance(p0);
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double d1 = progressToDistance(p1);
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path.Clear();
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int i = 0;
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for (; i < calculatedPath.Count && cumulativeLength[i] < d0; ++i)
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{
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}
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path.Add(interpolateVertices(i, d0));
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for (; i < calculatedPath.Count && cumulativeLength[i] <= d1; ++i)
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path.Add(calculatedPath[i]);
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path.Add(interpolateVertices(i, d1));
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}
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/// <summary>
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/// Computes the position on the slider at a given progress that ranges from 0 (beginning of the path)
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/// to 1 (end of the path).
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/// </summary>
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/// <param name="progress">Ranges from 0 (beginning of the path) to 1 (end of the path).</param>
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public Vector2 PositionAt(double progress)
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{
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ensureValid();
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double d = progressToDistance(progress);
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return interpolateVertices(indexOfDistance(d), d);
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}
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/// <summary>
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/// Returns the control points belonging to the same segment as the one given.
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/// The first point has a PathType which all other points inherit.
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/// </summary>
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/// <param name="controlPoint">One of the control points in the segment.</param>
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public List<PathControlPoint> PointsInSegment(PathControlPoint controlPoint)
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{
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bool found = false;
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List<PathControlPoint> pointsInCurrentSegment = new List<PathControlPoint>();
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foreach (PathControlPoint point in ControlPoints)
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{
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if (point.Type != null)
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{
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if (!found)
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pointsInCurrentSegment.Clear();
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else
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{
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pointsInCurrentSegment.Add(point);
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break;
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}
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}
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pointsInCurrentSegment.Add(point);
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if (point == controlPoint)
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found = true;
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}
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return pointsInCurrentSegment;
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}
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/// <summary>
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/// Returns the progress values at which (control point) segments of the path end.
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/// Ranges from 0 (beginning of the path) to 1 (end of the path) to infinity (beyond the end of the path).
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/// </summary>
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/// <remarks>
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/// <see cref="PositionAt"/> truncates the progression values to [0,1],
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/// so you can't use this method in conjunction with that one to retrieve the positions of segment ends beyond the end of the path.
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/// </remarks>
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/// <example>
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/// <para>
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/// In case <see cref="Distance"/> is less than <see cref="CalculatedDistance"/>,
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/// the last segment ends after the end of the path, hence it returns a value greater than 1.
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/// </para>
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/// <para>
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/// In case <see cref="Distance"/> is greater than <see cref="CalculatedDistance"/>,
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/// the last segment ends before the end of the path, hence it returns a value less than 1.
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/// </para>
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/// </example>
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public IEnumerable<double> GetSegmentEnds()
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{
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ensureValid();
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return segmentEndDistances.Select(d => d / Distance);
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}
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private void invalidate()
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{
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pathCache.Invalidate();
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version.Value++;
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}
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private void ensureValid()
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{
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if (pathCache.IsValid)
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return;
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calculatePath();
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calculateLength();
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pathCache.Validate();
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}
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private void calculatePath()
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{
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calculatedPath.Clear();
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segmentEnds.Clear();
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optimisedLength = 0;
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if (ControlPoints.Count == 0)
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return;
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Vector2[] vertices = new Vector2[ControlPoints.Count];
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for (int i = 0; i < ControlPoints.Count; i++)
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vertices[i] = ControlPoints[i].Position;
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int start = 0;
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for (int i = 0; i < ControlPoints.Count; i++)
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{
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if (ControlPoints[i].Type == null && i < ControlPoints.Count - 1)
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continue;
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// The current vertex ends the segment
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var segmentVertices = vertices.AsSpan().Slice(start, i - start + 1);
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var segmentType = ControlPoints[start].Type ?? PathType.LINEAR;
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// No need to calculate path when there is only 1 vertex
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if (segmentVertices.Length == 1)
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calculatedPath.Add(segmentVertices[0]);
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else if (segmentVertices.Length > 1)
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{
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List<Vector2> subPath = calculateSubPath(segmentVertices, segmentType);
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// Skip the first vertex if it is the same as the last vertex from the previous segment
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bool skipFirst = calculatedPath.Count > 0 && subPath.Count > 0 && calculatedPath.Last() == subPath[0];
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for (int j = skipFirst ? 1 : 0; j < subPath.Count; j++)
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calculatedPath.Add(subPath[j]);
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}
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if (i > 0)
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{
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// Remember the index of the segment end
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segmentEnds.Add(calculatedPath.Count - 1);
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}
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// Start the new segment at the current vertex
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start = i;
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}
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}
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private List<Vector2> calculateSubPath(ReadOnlySpan<Vector2> subControlPoints, PathType type)
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{
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switch (type.Type)
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{
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case SplineType.Linear:
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return PathApproximator.LinearToPiecewiseLinear(subControlPoints);
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case SplineType.PerfectCurve:
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{
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if (subControlPoints.Length != 3)
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break;
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CircularArcProperties circularArcProperties = new CircularArcProperties(subControlPoints);
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// `PathApproximator` will already internally revert to B-spline if the arc isn't valid.
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if (!circularArcProperties.IsValid)
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break;
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// taken from https://github.com/ppy/osu-framework/blob/1201e641699a1d50d2f6f9295192dad6263d5820/osu.Framework/Utils/PathApproximator.cs#L181-L186
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int subPoints = (2f * circularArcProperties.Radius <= 0.1f) ? 2 : Math.Max(2, (int)Math.Ceiling(circularArcProperties.ThetaRange / (2.0 * Math.Acos(1f - (0.1f / circularArcProperties.Radius)))));
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// 1000 subpoints requires an arc length of at least ~120 thousand to occur
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// See here for calculations https://www.desmos.com/calculator/umj6jvmcz7
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if (subPoints >= 1000)
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break;
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List<Vector2> subPath = PathApproximator.CircularArcToPiecewiseLinear(subControlPoints);
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// If for some reason a circular arc could not be fit to the 3 given points, fall back to a numerically stable bezier approximation.
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if (subPath.Count == 0)
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break;
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return subPath;
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}
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case SplineType.Catmull:
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{
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List<Vector2> subPath = PathApproximator.CatmullToPiecewiseLinear(subControlPoints);
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if (!OptimiseCatmull)
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return subPath;
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// At draw time, osu!stable optimises paths by only keeping piecewise segments that are 6px apart.
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// For the most part we don't care about this optimisation, and its additional heuristics are hard to reproduce in every implementation.
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//
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// However, it matters for Catmull paths which form "bulbs" around sequential knots with identical positions,
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// so we'll apply a very basic form of the optimisation here and return a length representing the optimised portion.
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// The returned length is important so that the optimisation doesn't cause the path to get extended to match the value of ExpectedDistance.
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List<Vector2> optimisedPath = new List<Vector2>(subPath.Count);
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Vector2? lastStart = null;
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double lengthRemovedSinceStart = 0;
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for (int i = 0; i < subPath.Count; i++)
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{
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if (lastStart == null)
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{
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optimisedPath.Add(subPath[i]);
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lastStart = subPath[i];
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continue;
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}
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Debug.Assert(i > 0);
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double distFromStart = Vector2.Distance(lastStart.Value, subPath[i]);
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lengthRemovedSinceStart += Vector2.Distance(subPath[i - 1], subPath[i]);
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// See PathApproximator.catmull_detail.
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const int catmull_detail = 50;
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const int catmull_segment_length = catmull_detail * 2;
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// Either 6px from the start, the last vertex at every knot, or the end of the path.
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if (distFromStart > 6 || (i + 1) % catmull_segment_length == 0 || i == subPath.Count - 1)
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{
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optimisedPath.Add(subPath[i]);
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optimisedLength += lengthRemovedSinceStart - distFromStart;
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lastStart = null;
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lengthRemovedSinceStart = 0;
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}
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}
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return optimisedPath;
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}
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}
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return PathApproximator.BSplineToPiecewiseLinear(subControlPoints, type.Degree ?? subControlPoints.Length);
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}
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private void calculateLength()
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{
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calculatedLength = optimisedLength;
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cumulativeLength.Clear();
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cumulativeLength.Add(0);
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for (int i = 0; i < calculatedPath.Count - 1; i++)
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{
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Vector2 diff = calculatedPath[i + 1] - calculatedPath[i];
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calculatedLength += diff.Length;
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cumulativeLength.Add(calculatedLength);
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}
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// Store the distances of the segment ends now, because after shortening the indices may be out of range
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segmentEndDistances = new double[segmentEnds.Count];
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for (int i = 0; i < segmentEnds.Count; i++)
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{
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segmentEndDistances[i] = cumulativeLength[segmentEnds[i]];
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}
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if (ExpectedDistance.Value is double expectedDistance && calculatedLength != expectedDistance)
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{
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// In osu-stable, if the last two path points of a slider are equal, extension is not performed.
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if (calculatedPath.Count >= 2 && calculatedPath[^1] == calculatedPath[^2] && expectedDistance > calculatedLength)
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{
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cumulativeLength.Add(calculatedLength);
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return;
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}
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// The last length is always incorrect
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cumulativeLength.RemoveAt(cumulativeLength.Count - 1);
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int pathEndIndex = calculatedPath.Count - 1;
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if (calculatedLength > expectedDistance)
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{
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// The path will be shortened further, in which case we should trim any more unnecessary lengths and their associated path segments
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while (cumulativeLength.Count > 0 && cumulativeLength[^1] >= expectedDistance)
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{
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cumulativeLength.RemoveAt(cumulativeLength.Count - 1);
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calculatedPath.RemoveAt(pathEndIndex--);
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}
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}
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if (pathEndIndex <= 0)
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{
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// The expected distance is negative or zero
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// TODO: Perhaps negative path lengths should be disallowed altogether
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cumulativeLength.Add(0);
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return;
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}
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// The direction of the segment to shorten or lengthen
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Vector2 dir = (calculatedPath[pathEndIndex] - calculatedPath[pathEndIndex - 1]).Normalized();
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calculatedPath[pathEndIndex] = calculatedPath[pathEndIndex - 1] + dir * (float)(expectedDistance - cumulativeLength[^1]);
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cumulativeLength.Add(expectedDistance);
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}
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}
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private int indexOfDistance(double d)
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{
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int i = cumulativeLength.BinarySearch(d);
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if (i < 0) i = ~i;
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return i;
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}
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private double progressToDistance(double progress)
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{
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return Math.Clamp(progress, 0, 1) * Distance;
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}
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private Vector2 interpolateVertices(int i, double d)
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{
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if (calculatedPath.Count == 0)
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return Vector2.Zero;
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if (i <= 0)
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return calculatedPath.First();
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if (i >= calculatedPath.Count)
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return calculatedPath.Last();
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Vector2 p0 = calculatedPath[i - 1];
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Vector2 p1 = calculatedPath[i];
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double d0 = cumulativeLength[i - 1];
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double d1 = cumulativeLength[i];
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// Avoid division by and almost-zero number in case two points are extremely close to each other.
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if (Precision.AlmostEquals(d0, d1))
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return p0;
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double w = (d - d0) / (d1 - d0);
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return p0 + (p1 - p0) * (float)w;
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}
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}
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}
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