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318 lines
11 KiB
C#
318 lines
11 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.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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/// <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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private double calculatedLength;
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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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foreach (var c in args.NewItems.Cast<PathControlPoint>())
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c.Changed += invalidate;
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break;
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case NotifyCollectionChangedAction.Remove:
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foreach (var c in args.OldItems.Cast<PathControlPoint>())
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c.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 ? (PathType?)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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/// <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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/// <returns></returns>
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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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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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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.Value;
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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.Value == 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.Value ?? PathType.Linear;
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foreach (Vector2 t in calculateSubPath(segmentVertices, segmentType))
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{
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if (calculatedPath.Count == 0 || calculatedPath.Last() != t)
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calculatedPath.Add(t);
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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)
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{
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case PathType.Linear:
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return PathApproximator.ApproximateLinear(subControlPoints);
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case PathType.PerfectCurve:
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if (subControlPoints.Length != 3)
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break;
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List<Vector2> subpath = PathApproximator.ApproximateCircularArc(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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case PathType.Catmull:
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return PathApproximator.ApproximateCatmull(subControlPoints);
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}
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return PathApproximator.ApproximateBezier(subControlPoints);
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}
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private void calculateLength()
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{
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calculatedLength = 0;
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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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if (ExpectedDistance.Value is double expectedDistance && calculatedLength != expectedDistance)
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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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