Group -> Connection

osu.Game.Rulesets.Osu/Objects/Drawables/Connections/FollowPointConnection.cs

@@ -0,0 +1,140 @@
+// 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;
+using JetBrains.Annotations;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Rulesets.Objects.Types;
+using osuTK;
+
+namespace osu.Game.Rulesets.Osu.Objects.Drawables.Connections
+{
+    /// <summary>
+    /// Visualises the <see cref="FollowPoint"/>s between two <see cref="DrawableOsuHitObject"/>s.
+    /// </summary>
+    public class FollowPointConnection : CompositeDrawable
+    {
+        // Todo: These shouldn't be constants
+        private const int spacing = 32;
+        private const double preempt = 800;
+
+        /// <summary>
+        /// The start time of <see cref="Start"/>.
+        /// </summary>
+        public readonly Bindable<double> StartTime = new Bindable<double>();
+
+        /// <summary>
+        /// The <see cref="DrawableOsuHitObject"/> which <see cref="FollowPoint"/>s will exit from.
+        /// </summary>
+        [NotNull]
+        public readonly DrawableOsuHitObject Start;
+
+        /// <summary>
+        /// Creates a new <see cref="FollowPointConnection"/>.
+        /// </summary>
+        /// <param name="start">The <see cref="DrawableOsuHitObject"/> which <see cref="FollowPoint"/>s will exit from.</param>
+        public FollowPointConnection([NotNull] DrawableOsuHitObject start)
+        {
+            Start = start;
+
+            RelativeSizeAxes = Axes.Both;
+
+            StartTime.BindTo(Start.HitObject.StartTimeBindable);
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+            bindEvents(Start);
+        }
+
+        private DrawableOsuHitObject end;
+
+        /// <summary>
+        /// The <see cref="DrawableOsuHitObject"/> which <see cref="FollowPoint"/>s will enter.
+        /// </summary>
+        [CanBeNull]
+        public DrawableOsuHitObject End
+        {
+            get => end;
+            set
+            {
+                end = value;
+
+                if (end != null)
+                    bindEvents(end);
+
+                if (IsLoaded)
+                    scheduleRefresh();
+                else
+                    refresh();
+            }
+        }
+
+        private void bindEvents(DrawableOsuHitObject drawableObject)
+        {
+            drawableObject.HitObject.PositionBindable.BindValueChanged(_ => scheduleRefresh());
+            drawableObject.HitObject.DefaultsApplied += scheduleRefresh;
+        }
+
+        private void scheduleRefresh() => Scheduler.AddOnce(refresh);
+
+        private void refresh()
+        {
+            ClearInternal();
+
+            if (End == null)
+                return;
+
+            OsuHitObject osuStart = Start.HitObject;
+            OsuHitObject osuEnd = End.HitObject;
+
+            if (osuEnd.NewCombo)
+                return;
+
+            if (osuStart is Spinner || osuEnd is Spinner)
+                return;
+
+            Vector2 startPosition = osuStart.EndPosition;
+            Vector2 endPosition = osuEnd.Position;
+            double startTime = (osuStart as IHasEndTime)?.EndTime ?? osuStart.StartTime;
+            double endTime = osuEnd.StartTime;
+
+            Vector2 distanceVector = endPosition - startPosition;
+            int distance = (int)distanceVector.Length;
+            float rotation = (float)(Math.Atan2(distanceVector.Y, distanceVector.X) * (180 / Math.PI));
+            double duration = endTime - startTime;
+
+            for (int d = (int)(spacing * 1.5); d < distance - spacing; d += spacing)
+            {
+                float fraction = (float)d / distance;
+                Vector2 pointStartPosition = startPosition + (fraction - 0.1f) * distanceVector;
+                Vector2 pointEndPosition = startPosition + fraction * distanceVector;
+                double fadeOutTime = startTime + fraction * duration;
+                double fadeInTime = fadeOutTime - preempt;
+
+                FollowPoint fp;
+
+                AddInternal(fp = new FollowPoint
+                {
+                    Position = pointStartPosition,
+                    Rotation = rotation,
+                    Alpha = 0,
+                    Scale = new Vector2(1.5f * osuEnd.Scale),
+                });
+
+                using (fp.BeginAbsoluteSequence(fadeInTime))
+                {
+                    fp.FadeIn(osuEnd.TimeFadeIn);
+                    fp.ScaleTo(osuEnd.Scale, osuEnd.TimeFadeIn, Easing.Out);
+                    fp.MoveTo(pointEndPosition, osuEnd.TimeFadeIn, Easing.Out);
+                    fp.Delay(fadeOutTime - fadeInTime).FadeOut(osuEnd.TimeFadeIn);
+                }
+
+                fp.Expire(true);
+            }
+        }
+    }
+}