osu/osu.Game/Rulesets/Objects/SliderCurve.cs

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// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
using System.Collections.Generic;
using System.Linq;
using osu.Framework.MathUtils;
using osu.Game.Rulesets.Objects.Types;
using OpenTK;
namespace osu.Game.Rulesets.Objects
{
public class SliderCurve
{
public double Distance;
public List<Vector2> ControlPoints;
public CurveType CurveType = CurveType.PerfectCurve;
public Vector2 Offset;
private readonly List<Vector2> calculatedPath = new List<Vector2>();
private readonly List<double> cumulativeLength = new List<double>();
private List<Vector2> calculateSubpath(List<Vector2> subControlPoints)
{
switch (CurveType)
{
case CurveType.Linear:
return subControlPoints;
case CurveType.PerfectCurve:
//we can only use CircularArc iff we have exactly three control points and no dissection.
if (ControlPoints.Count != 3 || subControlPoints.Count != 3)
break;
// Here we have exactly 3 control points. Attempt to fit a circular arc.
List<Vector2> subpath = new CircularArcApproximator(subControlPoints[0], subControlPoints[1], subControlPoints[2]).CreateArc();
// If for some reason a circular arc could not be fit to the 3 given points, fall back to a numerically stable bezier approximation.
if (subpath.Count == 0)
break;
return subpath;
case CurveType.Catmull:
return new CatmullApproximator(subControlPoints).CreateCatmull();
}
return new BezierApproximator(subControlPoints).CreateBezier();
}
private void calculatePath()
{
calculatedPath.Clear();
// Sliders may consist of various subpaths separated by two consecutive vertices
// with the same position. The following loop parses these subpaths and computes
// their shape independently, consecutively appending them to calculatedPath.
List<Vector2> subControlPoints = new List<Vector2>();
for (int i = 0; i < ControlPoints.Count; ++i)
{
subControlPoints.Add(ControlPoints[i]);
if (i == ControlPoints.Count - 1 || ControlPoints[i] == ControlPoints[i + 1])
{
List<Vector2> subpath = calculateSubpath(subControlPoints);
foreach (Vector2 t in subpath)
if (calculatedPath.Count == 0 || calculatedPath.Last() != t)
calculatedPath.Add(t);
subControlPoints.Clear();
}
}
}
private void calculateCumulativeLengthAndTrimPath()
{
double l = 0;
cumulativeLength.Clear();
cumulativeLength.Add(l);
for (int i = 0; i < calculatedPath.Count - 1; ++i)
{
Vector2 diff = calculatedPath[i + 1] - calculatedPath[i];
double d = diff.Length;
// Shorten slider curves that are too long compared to what's
// in the .osu file.
if (Distance - l < d)
{
calculatedPath[i + 1] = calculatedPath[i] + diff * (float)((Distance - l) / d);
calculatedPath.RemoveRange(i + 2, calculatedPath.Count - 2 - i);
l = Distance;
cumulativeLength.Add(l);
break;
}
l += d;
cumulativeLength.Add(l);
}
// Lengthen slider curves that are too short compared to what's
// in the .osu file.
if (l < Distance && calculatedPath.Count > 1)
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{
Vector2 diff = calculatedPath[calculatedPath.Count - 1] - calculatedPath[calculatedPath.Count - 2];
double d = diff.Length;
if (d <= 0)
return;
calculatedPath[calculatedPath.Count - 1] += diff * (float)((Distance - l) / d);
cumulativeLength[calculatedPath.Count - 1] = Distance;
}
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}
public void Calculate()
{
calculatePath();
calculateCumulativeLengthAndTrimPath();
}
private int indexOfDistance(double d)
{
int i = cumulativeLength.BinarySearch(d);
if (i < 0) i = ~i;
return i;
}
private double progressToDistance(double progress)
{
return MathHelper.Clamp(progress, 0, 1) * Distance;
}
private Vector2 interpolateVertices(int i, double d)
{
if (calculatedPath.Count == 0)
return Vector2.Zero;
if (i <= 0)
return calculatedPath.First();
else if (i >= calculatedPath.Count)
return calculatedPath.Last();
Vector2 p0 = calculatedPath[i - 1];
Vector2 p1 = calculatedPath[i];
double d0 = cumulativeLength[i - 1];
double d1 = cumulativeLength[i];
// Avoid division by and almost-zero number in case two points are extremely close to each other.
if (Precision.AlmostEquals(d0, d1))
return p0;
double w = (d - d0) / (d1 - d0);
return p0 + (p1 - p0) * (float)w;
}
/// <summary>
/// Computes the slider curve until a given progress that ranges from 0 (beginning of the slider)
/// to 1 (end of the slider) and stores the generated path in the given list.
/// </summary>
/// <param name="path">The list to be filled with the computed curve.</param>
/// <param name="p0">Start progress. Ranges from 0 (beginning of the slider) to 1 (end of the slider).</param>
/// <param name="p1">End progress. Ranges from 0 (beginning of the slider) to 1 (end of the slider).</param>
public void GetPathToProgress(List<Vector2> path, double p0, double p1)
{
if (calculatedPath.Count == 0 && ControlPoints.Count > 0)
Calculate();
double d0 = progressToDistance(p0);
double d1 = progressToDistance(p1);
path.Clear();
int i = 0;
for (; i < calculatedPath.Count && cumulativeLength[i] < d0; ++i) { }
path.Add(interpolateVertices(i, d0) + Offset);
for (; i < calculatedPath.Count && cumulativeLength[i] <= d1; ++i)
path.Add(calculatedPath[i] + Offset);
path.Add(interpolateVertices(i, d1) + Offset);
}
/// <summary>
/// Computes the position on the slider at a given progress that ranges from 0 (beginning of the curve)
/// to 1 (end of the curve).
/// </summary>
/// <param name="progress">Ranges from 0 (beginning of the curve) to 1 (end of the curve).</param>
/// <returns></returns>
public Vector2 PositionAt(double progress)
{
if (calculatedPath.Count == 0 && ControlPoints.Count > 0)
Calculate();
double d = progressToDistance(progress);
return interpolateVertices(indexOfDistance(d), d) + Offset;
}
}
}