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Code Issues Releases Wiki Activity

Fix incorrect way of calculating SliderCurve.PositionAt.

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This commit is contained in:
Thomas Müller 2016-12-03 10:41:03 +01:00
parent 08f9d329b9
commit c6e099d725
1 changed files with 36 additions and 8 deletions
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44
osu.Game.Mode.Osu/Objects/SliderCurve.cs
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@ -1,5 +1,8 @@
using System.Collections.Generic; using System.Collections.Generic;
using OpenTK; using OpenTK;
using System.Linq;
using System.Diagnostics;
using osu.Framework.MathUtils;
namespace osu.Game.Modes.Osu.Objects namespace osu.Game.Modes.Osu.Objects
{ {
@ -11,7 +14,8 @@ namespace osu.Game.Modes.Osu.Objects
public CurveTypes CurveType; public CurveTypes CurveType;
private List<Vector2> calculatedPath; private List<Vector2> calculatedPath = new List<Vector2>();
private List<double> cumulativeLength = new List<double>();
private List<Vector2> calculateSubpath(List<Vector2> subpath) private List<Vector2> calculateSubpath(List<Vector2> subpath)
{ {
@ -26,7 +30,7 @@ namespace osu.Game.Modes.Osu.Objects
public void Calculate() public void Calculate()
{ {
calculatedPath = new List<Vector2>(); calculatedPath.Clear();
// Sliders may consist of various subpaths separated by two consecutive vertices // Sliders may consist of various subpaths separated by two consecutive vertices
// with the same position. The following loop parses these subpaths and computes // with the same position. The following loop parses these subpaths and computes
@ -48,20 +52,44 @@ namespace osu.Game.Modes.Osu.Objects
subpath.Clear(); subpath.Clear();
} }
} }
cumulativeLength.Clear();
cumulativeLength.Add(Length = 0);
for (int i = 0; i < calculatedPath.Count - 1; ++i)
{
double d = (calculatedPath[i + 1] - calculatedPath[i]).Length;
Debug.Assert(d >= 0, "Cumulative lengths have to be strictly increasing.");
cumulativeLength.Add(Length += d);
}
} }
public Vector2 PositionAt(double progress) public Vector2 PositionAt(double progress)
{ {
progress = MathHelper.Clamp(progress, 0, 1); progress = MathHelper.Clamp(progress, 0, 1);
double index = progress * (calculatedPath.Count - 1); double d = progress * Length;
int flooredIndex = (int)index; int i = cumulativeLength.BinarySearch(d);
if (i < 0) i = ~i;
Vector2 pos = calculatedPath[flooredIndex]; if (i >= calculatedPath.Count)
if (index != flooredIndex) return calculatedPath.Last();
pos += (calculatedPath[flooredIndex + 1] - pos) * (float)(index - flooredIndex);
return pos; if (i <= 0)
return calculatedPath.First();
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;
} }
} }
} }