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203 lines
7.7 KiB
C#
203 lines
7.7 KiB
C#
// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
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// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
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using System.Collections.Generic;
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using System.Linq;
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using osu.Framework.MathUtils;
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using osu.Game.Rulesets.Objects.Types;
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using OpenTK;
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namespace osu.Game.Rulesets.Objects
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{
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public class SliderCurve
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{
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public double Distance;
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public List<Vector2> ControlPoints;
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public CurveType CurveType = CurveType.PerfectCurve;
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public Vector2 Offset;
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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 List<Vector2> calculateSubpath(List<Vector2> subControlPoints)
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{
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switch (CurveType)
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{
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case CurveType.Linear:
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return subControlPoints;
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case CurveType.PerfectCurve:
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//we can only use CircularArc iff we have exactly three control points and no dissection.
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if (ControlPoints.Count != 3 || subControlPoints.Count != 3)
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break;
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// Here we have exactly 3 control points. Attempt to fit a circular arc.
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List<Vector2> subpath = new CircularArcApproximator(subControlPoints[0], subControlPoints[1], subControlPoints[2]).CreateArc();
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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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return new BezierApproximator(subControlPoints).CreateBezier();
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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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// Sliders may consist of various subpaths separated by two consecutive vertices
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// with the same position. The following loop parses these subpaths and computes
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// their shape independently, consecutively appending them to calculatedPath.
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List<Vector2> subControlPoints = new List<Vector2>();
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for (int i = 0; i < ControlPoints.Count; ++i)
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{
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subControlPoints.Add(ControlPoints[i]);
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if (i == ControlPoints.Count - 1 || ControlPoints[i] == ControlPoints[i + 1])
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{
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List<Vector2> subpath = calculateSubpath(subControlPoints);
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foreach (Vector2 t in subpath)
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if (calculatedPath.Count == 0 || calculatedPath.Last() != t)
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calculatedPath.Add(t);
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subControlPoints.Clear();
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}
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}
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}
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private void calculateCumulativeLengthAndTrimPath()
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{
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double l = 0;
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cumulativeLength.Clear();
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cumulativeLength.Add(l);
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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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double d = diff.Length;
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// Shorten slider curves that are too long compared to what's
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// in the .osu file.
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if (Distance - l < d)
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{
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calculatedPath[i + 1] = calculatedPath[i] + diff * (float)((Distance - l) / d);
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calculatedPath.RemoveRange(i + 2, calculatedPath.Count - 2 - i);
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l = Distance;
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cumulativeLength.Add(l);
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break;
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}
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l += d;
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cumulativeLength.Add(l);
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}
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//TODO: Figure out if the following code is needed in some cases. Judging by the map
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// "Transform" http://osu.ppy.sh/s/484689 it seems like we should _not_ be doing this.
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// Lengthen slider curves that are too short compared to what's
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// in the .osu file.
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/*if (l < Length && calculatedPath.Count > 1)
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{
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Vector2 diff = calculatedPath[calculatedPath.Count - 1] - calculatedPath[calculatedPath.Count - 2];
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double d = diff.Length;
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if (d <= 0)
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return;
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calculatedPath[calculatedPath.Count - 1] += diff * (float)((Length - l) / d);
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cumulativeLength[calculatedPath.Count - 1] = Length;
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}*/
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}
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public void Calculate()
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{
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calculatePath();
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calculateCumulativeLengthAndTrimPath();
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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 MathHelper.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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else 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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/// <summary>
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/// Computes the slider curve 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 curve.</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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if (calculatedPath.Count == 0 && ControlPoints.Count > 0)
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Calculate();
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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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path.Add(interpolateVertices(i, d0) + Offset);
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for (; i < calculatedPath.Count && cumulativeLength[i] <= d1; ++i)
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path.Add(calculatedPath[i] + Offset);
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path.Add(interpolateVertices(i, d1) + Offset);
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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 curve)
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/// to 1 (end of the curve).
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/// </summary>
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/// <param name="progress">Ranges from 0 (beginning of the curve) to 1 (end of the curve).</param>
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/// <returns></returns>
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public Vector2 PositionAt(double progress)
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{
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if (calculatedPath.Count == 0 && ControlPoints.Count > 0)
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Calculate();
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double d = progressToDistance(progress);
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return interpolateVertices(indexOfDistance(d), d) + Offset;
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}
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}
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} |