From 7ef7c5148f21c35426a45f4ae02d6a60755fc584 Mon Sep 17 00:00:00 2001
From: ekrctb <ekrctb@gmail.com>
Date: Tue, 6 Jul 2021 16:19:31 +0900
Subject: [PATCH] Add `ScrollingPath` for visualization of the real path of a
 `JuiceStream`

---
 .../Blueprints/Components/ScrollingPath.cs    | 79 +++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 osu.Game.Rulesets.Catch/Edit/Blueprints/Components/ScrollingPath.cs

diff --git a/osu.Game.Rulesets.Catch/Edit/Blueprints/Components/ScrollingPath.cs b/osu.Game.Rulesets.Catch/Edit/Blueprints/Components/ScrollingPath.cs
new file mode 100644
index 0000000000..337b8de92e
--- /dev/null
+++ b/osu.Game.Rulesets.Catch/Edit/Blueprints/Components/ScrollingPath.cs
@@ -0,0 +1,79 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using System.Linq;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Lines;
+using osu.Game.Rulesets.Catch.Objects;
+using osu.Game.Rulesets.UI.Scrolling;
+using osuTK;
+
+namespace osu.Game.Rulesets.Catch.Edit.Blueprints.Components
+{
+    public class ScrollingPath : CompositeDrawable
+    {
+        private readonly Path drawablePath;
+
+        private readonly List<(double Distance, float X)> vertices = new List<(double, float)>();
+
+        public ScrollingPath()
+        {
+            Anchor = Anchor.BottomLeft;
+
+            InternalChildren = new Drawable[]
+            {
+                drawablePath = new SmoothPath
+                {
+                    PathRadius = 2,
+                    Alpha = 0.5f
+                },
+            };
+        }
+
+        public void UpdatePositionFrom(ScrollingHitObjectContainer hitObjectContainer, CatchHitObject hitObject)
+        {
+            X = hitObject.OriginalX;
+            Y = hitObjectContainer.PositionAtTime(hitObject.StartTime);
+        }
+
+        public void UpdatePathFrom(ScrollingHitObjectContainer hitObjectContainer, JuiceStream hitObject)
+        {
+            double distanceToYFactor = -hitObjectContainer.LengthAtTime(hitObject.StartTime, hitObject.StartTime + 1 / hitObject.Velocity);
+
+            computeDistanceXs(hitObject);
+            drawablePath.Vertices = vertices
+                                    .Select(v => new Vector2(v.X, (float)(v.Distance * distanceToYFactor)))
+                                    .ToArray();
+            drawablePath.OriginPosition = drawablePath.PositionInBoundingBox(Vector2.Zero);
+        }
+
+        private void computeDistanceXs(JuiceStream hitObject)
+        {
+            vertices.Clear();
+
+            var sliderVertices = new List<Vector2>();
+            hitObject.Path.GetPathToProgress(sliderVertices, 0, 1);
+
+            if (sliderVertices.Count == 0)
+                return;
+
+            double distance = 0;
+            Vector2 lastPosition = Vector2.Zero;
+
+            for (int repeat = 0; repeat < hitObject.RepeatCount + 1; repeat++)
+            {
+                foreach (var position in sliderVertices)
+                {
+                    distance += Vector2.Distance(lastPosition, position);
+                    lastPosition = position;
+
+                    vertices.Add((distance, position.X));
+                }
+
+                sliderVertices.Reverse();
+            }
+        }
+    }
+}