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322 lines
13 KiB
C#
322 lines
13 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.Linq;
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using osu.Framework.Utils;
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using osu.Game.Rulesets.Objects;
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using osu.Game.Rulesets.Objects.Types;
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using osuTK;
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namespace osu.Game.Rulesets.Catch.Objects
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{
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/// <summary>
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/// Represents the path of a juice stream.
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/// <para>
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/// A <see cref="JuiceStream"/> holds a legacy <see cref="SliderPath"/> as the representation of the path.
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/// However, the <see cref="SliderPath"/> representation is difficult to work with.
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/// This <see cref="JuiceStreamPath"/> represents the path in a more convenient way, a polyline connecting list of <see cref="JuiceStreamPathVertex"/>s.
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/// </para>
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/// </summary>
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public class JuiceStreamPath
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{
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/// <summary>
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/// The height of legacy osu!standard playfield.
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/// The sliders converted by <see cref="ConvertToSliderPath"/> are vertically contained in this height.
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/// </summary>
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internal const float OSU_PLAYFIELD_HEIGHT = 384;
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/// <summary>
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/// The list of vertices of the path, which is represented as a polyline connecting the vertices.
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/// </summary>
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public IReadOnlyList<JuiceStreamPathVertex> Vertices => vertices;
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/// <summary>
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/// The current version number.
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/// This starts from <c>1</c> and incremented whenever this <see cref="JuiceStreamPath"/> is modified.
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/// </summary>
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public int InvalidationID { get; private set; } = 1;
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/// <summary>
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/// The difference between first vertex's <see cref="JuiceStreamPathVertex.Time"/> and last vertex's <see cref="JuiceStreamPathVertex.Time"/>.
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/// </summary>
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public double Duration => vertices[^1].Time - vertices[0].Time;
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/// <remarks>
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/// This list should always be non-empty.
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/// </remarks>
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private readonly List<JuiceStreamPathVertex> vertices = new List<JuiceStreamPathVertex>
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{
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new JuiceStreamPathVertex()
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};
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/// <summary>
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/// Compute the x-position of the path at the given <paramref name="time"/>.
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/// </summary>
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/// <remarks>
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/// When the given time is outside of the path, the x position at the corresponding endpoint is returned,
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/// </remarks>
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public float PositionAtTime(double time)
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{
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int index = vertexIndexAtTime(time);
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return positionAtTime(time, index);
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}
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/// <summary>
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/// Remove all vertices of this path, then add a new vertex <c>(0, 0)</c>.
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/// </summary>
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public void Clear()
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{
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vertices.Clear();
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vertices.Add(new JuiceStreamPathVertex());
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invalidate();
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}
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/// <summary>
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/// Insert a vertex at given <paramref name="time"/>.
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/// The <see cref="PositionAtTime"/> is used as the position of the new vertex.
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/// Thus, the set of points of the path is not changed (up to floating-point precision).
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/// </summary>
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/// <returns>The index of the new vertex.</returns>
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public int InsertVertex(double time)
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{
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if (!double.IsFinite(time))
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throw new ArgumentOutOfRangeException(nameof(time));
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int index = vertexIndexAtTime(time);
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float x = positionAtTime(time, index);
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vertices.Insert(index, new JuiceStreamPathVertex(time, x));
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invalidate();
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return index;
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}
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/// <summary>
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/// Move the vertex of given <paramref name="index"/> to the given position <paramref name="newX"/>.
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/// </summary>
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public void SetVertexPosition(int index, float newX)
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{
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if (index < 0 || index >= vertices.Count)
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throw new ArgumentOutOfRangeException(nameof(index));
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if (!float.IsFinite(newX))
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throw new ArgumentOutOfRangeException(nameof(newX));
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vertices[index] = new JuiceStreamPathVertex(vertices[index].Time, newX);
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invalidate();
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}
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/// <summary>
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/// Add a new vertex at given <paramref name="time"/> and position.
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/// </summary>
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public void Add(double time, float x)
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{
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int index = InsertVertex(time);
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SetVertexPosition(index, x);
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}
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/// <summary>
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/// Remove all vertices that satisfy the given <paramref name="predicate"/>.
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/// </summary>
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/// <remarks>
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/// If all vertices are removed, a new vertex <c>(0, 0)</c> is added.
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/// </remarks>
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/// <param name="predicate">The predicate to determine whether a vertex should be removed given the vertex and its index in the path.</param>
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/// <returns>The number of removed vertices.</returns>
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public int RemoveVertices(Func<JuiceStreamPathVertex, int, bool> predicate)
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{
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int index = 0;
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int removeCount = vertices.RemoveAll(vertex => predicate(vertex, index++));
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if (vertices.Count == 0)
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vertices.Add(new JuiceStreamPathVertex());
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if (removeCount != 0)
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invalidate();
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return removeCount;
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}
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/// <summary>
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/// Recreate this path by using difference set of vertices at given time points.
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/// In addition to the given <paramref name="sampleTimes"/>, the first vertex and the last vertex are always added to the new path.
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/// New vertices use the positions on the original path. Thus, <see cref="PositionAtTime"/>s at <paramref name="sampleTimes"/> are preserved.
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/// </summary>
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public void ResampleVertices(IEnumerable<double> sampleTimes)
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{
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var sampledVertices = new List<JuiceStreamPathVertex>();
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foreach (double time in sampleTimes)
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{
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if (!double.IsFinite(time))
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throw new ArgumentOutOfRangeException(nameof(sampleTimes));
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double clampedTime = Math.Clamp(time, vertices[0].Time, vertices[^1].Time);
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float x = PositionAtTime(clampedTime);
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sampledVertices.Add(new JuiceStreamPathVertex(clampedTime, x));
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}
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sampledVertices.Sort();
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// The first vertex and the last vertex are always used in the result.
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vertices.RemoveRange(1, vertices.Count - (vertices.Count == 1 ? 1 : 2));
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vertices.InsertRange(1, sampledVertices);
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invalidate();
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}
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/// <summary>
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/// Convert a <see cref="SliderPath"/> to list of vertices and write the result to this <see cref="JuiceStreamPath"/>.
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/// </summary>
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/// <remarks>
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/// Duplicated vertices are automatically removed.
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/// </remarks>
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public void ConvertFromSliderPath(SliderPath sliderPath, double velocity)
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{
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var sliderPathVertices = new List<Vector2>();
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sliderPath.GetPathToProgress(sliderPathVertices, 0, 1);
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double time = 0;
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vertices.Clear();
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vertices.Add(new JuiceStreamPathVertex(0, sliderPathVertices.FirstOrDefault().X));
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for (int i = 1; i < sliderPathVertices.Count; i++)
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{
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time += Vector2.Distance(sliderPathVertices[i - 1], sliderPathVertices[i]) / velocity;
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if (!Precision.AlmostEquals(vertices[^1].Time, time))
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Add(time, sliderPathVertices[i].X);
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}
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invalidate();
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}
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/// <summary>
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/// Computes the minimum slider velocity required to convert this path to a <see cref="SliderPath"/>.
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/// </summary>
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public double ComputeRequiredVelocity()
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{
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double maximumSlope = 0;
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for (int i = 1; i < vertices.Count; i++)
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{
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double xDifference = Math.Abs((double)vertices[i].X - vertices[i - 1].X);
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double timeDifference = vertices[i].Time - vertices[i - 1].Time;
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// A short segment won't affect the resulting path much anyways so ignore it to avoid divide-by-zero.
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if (Precision.AlmostEquals(timeDifference, 0))
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continue;
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maximumSlope = Math.Max(maximumSlope, xDifference / timeDifference);
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}
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return maximumSlope;
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}
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/// <summary>
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/// Convert the path of this <see cref="JuiceStreamPath"/> to a <see cref="SliderPath"/> and write the result to <paramref name="sliderPath"/>.
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/// The resulting slider is "folded" to make it vertically contained in the playfield `(0..<see cref="OSU_PLAYFIELD_HEIGHT"/>)` assuming the slider start position is <paramref name="sliderStartY"/>.
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///
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/// The velocity of the converted slider is assumed to be <paramref name="velocity"/>.
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/// To preserve the path, <paramref name="velocity"/> should be at least the value returned by <see cref="ComputeRequiredVelocity"/>.
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/// </summary>
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public void ConvertToSliderPath(SliderPath sliderPath, float sliderStartY, double velocity)
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{
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const float margin = 1;
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// Note: these two variables and `sliderPath` are modified by the local functions.
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double currentTime = 0;
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Vector2 lastPosition = new Vector2(vertices[0].X, 0);
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sliderPath.ControlPoints.Clear();
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sliderPath.ControlPoints.Add(new PathControlPoint(lastPosition));
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for (int i = 1; i < vertices.Count; i++)
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{
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sliderPath.ControlPoints[^1].Type = PathType.Linear;
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float deltaX = vertices[i].X - lastPosition.X;
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double length = (vertices[i].Time - currentTime) * velocity;
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// Should satisfy `deltaX^2 + deltaY^2 = length^2`.
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// The expression inside the `sqrt` is (almost) non-negative if the slider velocity is large enough.
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double deltaY = Math.Sqrt(Math.Max(0, length * length - (double)deltaX * deltaX));
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// When `deltaY` is small, one segment is always enough.
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// This case is handled separately to prevent divide-by-zero.
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if (deltaY <= OSU_PLAYFIELD_HEIGHT / 2 - margin)
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{
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float nextX = vertices[i].X;
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float nextY = (float)(lastPosition.Y + getYDirection() * deltaY);
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addControlPoint(nextX, nextY);
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continue;
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}
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// When `deltaY` is large or when the slider velocity is fast, the segment must be partitioned to subsegments to stay in bounds.
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for (double currentProgress = 0; currentProgress < deltaY;)
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{
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double nextProgress = Math.Min(currentProgress + getMaxDeltaY(), deltaY);
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float nextX = (float)(vertices[i - 1].X + nextProgress / deltaY * deltaX);
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float nextY = (float)(lastPosition.Y + getYDirection() * (nextProgress - currentProgress));
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addControlPoint(nextX, nextY);
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currentProgress = nextProgress;
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}
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}
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int getYDirection()
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{
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float lastSliderY = sliderStartY + lastPosition.Y;
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return lastSliderY < OSU_PLAYFIELD_HEIGHT / 2 ? 1 : -1;
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}
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float getMaxDeltaY()
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{
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float lastSliderY = sliderStartY + lastPosition.Y;
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return Math.Max(lastSliderY, OSU_PLAYFIELD_HEIGHT - lastSliderY) - margin;
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}
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void addControlPoint(float nextX, float nextY)
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{
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Vector2 nextPosition = new Vector2(nextX, nextY);
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sliderPath.ControlPoints.Add(new PathControlPoint(nextPosition));
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currentTime += Vector2.Distance(lastPosition, nextPosition) / velocity;
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lastPosition = nextPosition;
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}
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}
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/// <summary>
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/// Find the index at which a new vertex with <paramref name="time"/> can be inserted.
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/// </summary>
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private int vertexIndexAtTime(double time)
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{
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// The position of `(time, Infinity)` is uniquely determined because infinite positions are not allowed.
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int i = vertices.BinarySearch(new JuiceStreamPathVertex(time, float.PositiveInfinity));
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return i < 0 ? ~i : i;
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}
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/// <summary>
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/// Compute the position at the given <paramref name="time"/>, assuming <paramref name="index"/> is the vertex index returned by <see cref="vertexIndexAtTime"/>.
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/// </summary>
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private float positionAtTime(double time, int index)
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{
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if (index <= 0)
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return vertices[0].X;
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if (index >= vertices.Count)
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return vertices[^1].X;
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double duration = vertices[index].Time - vertices[index - 1].Time;
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if (Precision.AlmostEquals(duration, 0))
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return vertices[index].X;
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float deltaX = vertices[index].X - vertices[index - 1].X;
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return (float)(vertices[index - 1].X + deltaX * ((time - vertices[index - 1].Time) / duration));
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}
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private void invalidate() => InvalidationID++;
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}
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}
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