osu-lazer/osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs

// 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 System.Linq;
using JetBrains.Annotations;
using osu.Framework.Allocation;
using osu.Framework.Bindables;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Game.Audio;
using osu.Game.Rulesets.Objects;
using osu.Game.Rulesets.Objects.Drawables;
using osu.Game.Rulesets.Osu.Skinning;
using osu.Game.Rulesets.Osu.Skinning.Default;
using osu.Game.Rulesets.Scoring;
using osu.Game.Skinning;
using osuTK;
using osuTK.Graphics;

namespace osu.Game.Rulesets.Osu.Objects.Drawables
{
    public class DrawableSlider : DrawableOsuHitObject
    {
        public new Slider HitObject => (Slider)base.HitObject;

        public DrawableSliderHead HeadCircle => headContainer.Child;
        public DrawableSliderTail TailCircle => tailContainer.Child;

        public SliderBall Ball { get; private set; }
        public SkinnableDrawable Body { get; private set; }

        /// <summary>
        /// A target container which can be used to add top level elements to the slider's display.
        /// Intended to be used for proxy purposes only.
        /// </summary>
        public Container OverlayElementContainer { get; private set; }

        public override bool DisplayResult => !HitObject.OnlyJudgeNestedObjects;

        [CanBeNull]
        public PlaySliderBody SliderBody => Body.Drawable as PlaySliderBody;

        public IBindable<int> PathVersion => pathVersion;
        private readonly Bindable<int> pathVersion = new Bindable<int>();

        private Container<DrawableSliderHead> headContainer;
        private Container<DrawableSliderTail> tailContainer;
        private Container<DrawableSliderTick> tickContainer;
        private Container<DrawableSliderRepeat> repeatContainer;
        private PausableSkinnableSound slidingSample;

        public DrawableSlider()
            : this(null)
        {
        }

        public DrawableSlider([CanBeNull] Slider s = null)
            : base(s)
        {
        }

        [BackgroundDependencyLoader]
        private void load()
        {
            InternalChildren = new Drawable[]
            {
                Body = new SkinnableDrawable(new OsuSkinComponent(OsuSkinComponents.SliderBody), _ => new DefaultSliderBody(), confineMode: ConfineMode.NoScaling),
                tailContainer = new Container<DrawableSliderTail> { RelativeSizeAxes = Axes.Both },
                tickContainer = new Container<DrawableSliderTick> { RelativeSizeAxes = Axes.Both },
                repeatContainer = new Container<DrawableSliderRepeat> { RelativeSizeAxes = Axes.Both },
                headContainer = new Container<DrawableSliderHead> { RelativeSizeAxes = Axes.Both },
                OverlayElementContainer = new Container { RelativeSizeAxes = Axes.Both, },
                Ball = new SliderBall(this)
                {
                    GetInitialHitAction = () => HeadCircle.HitAction,
                    BypassAutoSizeAxes = Axes.Both,
                    AlwaysPresent = true,
                    Alpha = 0
                },
                slidingSample = new PausableSkinnableSound { Looping = true }
            };

            PositionBindable.BindValueChanged(_ => Position = HitObject.StackedPosition);
            StackHeightBindable.BindValueChanged(_ => Position = HitObject.StackedPosition);
            ScaleBindable.BindValueChanged(scale => Ball.Scale = new Vector2(scale.NewValue));

            AccentColour.BindValueChanged(colour =>
            {
                foreach (var drawableHitObject in NestedHitObjects)
                    drawableHitObject.AccentColour.Value = colour.NewValue;
                updateBallTint();
            }, true);

            Tracking.BindValueChanged(updateSlidingSample);
        }

        protected override void OnApply()
        {
            base.OnApply();

            // Ensure that the version will change after the upcoming BindTo().
            pathVersion.Value = int.MaxValue;
            PathVersion.BindTo(HitObject.Path.Version);
        }

        protected override void OnFree()
        {
            base.OnFree();

            PathVersion.UnbindFrom(HitObject.Path.Version);

            slidingSample.Samples = null;
        }

        protected override void LoadSamples()
        {
            // Note: base.LoadSamples() isn't called since the slider plays the tail's hitsounds for the time being.

            if (HitObject.SampleControlPoint == null)
            {
                throw new InvalidOperationException($"{nameof(HitObject)}s must always have an attached {nameof(HitObject.SampleControlPoint)}."
                                                    + $" This is an indication that {nameof(HitObject.ApplyDefaults)} has not been invoked on {this}.");
            }

            Samples.Samples = HitObject.TailSamples.Select(s => HitObject.SampleControlPoint.ApplyTo(s)).Cast<ISampleInfo>().ToArray();
            slidingSample.Samples = HitObject.CreateSlidingSamples().Select(s => HitObject.SampleControlPoint.ApplyTo(s)).Cast<ISampleInfo>().ToArray();
        }

        public override void StopAllSamples()
        {
            base.StopAllSamples();
            slidingSample?.Stop();
        }

        private void updateSlidingSample(ValueChangedEvent<bool> tracking)
        {
            if (tracking.NewValue)
                slidingSample?.Play();
            else
                slidingSample?.Stop();
        }

        protected override void AddNestedHitObject(DrawableHitObject hitObject)
        {
            base.AddNestedHitObject(hitObject);

            switch (hitObject)
            {
                case DrawableSliderHead head:
                    headContainer.Child = head;
                    break;

                case DrawableSliderTail tail:
                    tailContainer.Child = tail;
                    break;

                case DrawableSliderTick tick:
                    tickContainer.Add(tick);
                    break;

                case DrawableSliderRepeat repeat:
                    repeatContainer.Add(repeat);
                    break;
            }
        }

        protected override void ClearNestedHitObjects()
        {
            base.ClearNestedHitObjects();

            headContainer.Clear(false);
            tailContainer.Clear(false);
            repeatContainer.Clear(false);
            tickContainer.Clear(false);

            OverlayElementContainer.Clear(false);
        }

        protected override DrawableHitObject CreateNestedHitObject(HitObject hitObject)
        {
            switch (hitObject)
            {
                case SliderTailCircle tail:
                    return new DrawableSliderTail(tail);

                case SliderHeadCircle head:
                    return new DrawableSliderHead(head);

                case SliderTick tick:
                    return new DrawableSliderTick(tick);

                case SliderRepeat repeat:
                    return new DrawableSliderRepeat(repeat);
            }

            return base.CreateNestedHitObject(hitObject);
        }

        public readonly Bindable<bool> Tracking = new Bindable<bool>();

        protected override void Update()
        {
            base.Update();

            Tracking.Value = Ball.Tracking;

            if (Tracking.Value && slidingSample != null)
                // keep the sliding sample playing at the current tracking position
                slidingSample.Balance.Value = CalculateSamplePlaybackBalance(CalculateDrawableRelativePosition(Ball));

            double completionProgress = Math.Clamp((Time.Current - HitObject.StartTime) / HitObject.Duration, 0, 1);

            Ball.UpdateProgress(completionProgress);
            SliderBody?.UpdateProgress(completionProgress);

            foreach (DrawableHitObject hitObject in NestedHitObjects)
            {
                if (hitObject is ITrackSnaking s) s.UpdateSnakingPosition(HitObject.Path.PositionAt(SliderBody?.SnakedStart ?? 0), HitObject.Path.PositionAt(SliderBody?.SnakedEnd ?? 0));
                if (hitObject is IRequireTracking t) t.Tracking = Ball.Tracking;
            }

            Size = SliderBody?.Size ?? Vector2.Zero;
            OriginPosition = SliderBody?.PathOffset ?? Vector2.Zero;

            if (DrawSize != Vector2.Zero)
            {
                var childAnchorPosition = Vector2.Divide(OriginPosition, DrawSize);
                foreach (var obj in NestedHitObjects)
                    obj.RelativeAnchorPosition = childAnchorPosition;
                Ball.RelativeAnchorPosition = childAnchorPosition;
            }
        }

        public override void OnKilled()
        {
            base.OnKilled();
            SliderBody?.RecyclePath();
        }

        protected override void ApplySkin(ISkinSource skin, bool allowFallback)
        {
            base.ApplySkin(skin, allowFallback);

            updateBallTint();
        }

        private void updateBallTint()
        {
            if (CurrentSkin == null)
                return;

            bool allowBallTint = CurrentSkin.GetConfig<OsuSkinConfiguration, bool>(OsuSkinConfiguration.AllowSliderBallTint)?.Value ?? false;
            Ball.AccentColour = allowBallTint ? AccentColour.Value : Color4.White;
        }

        protected override void CheckForResult(bool userTriggered, double timeOffset)
        {
            if (userTriggered || Time.Current < HitObject.EndTime)
                return;

            // If only the nested hitobjects are judged, then the slider's own judgement is ignored for scoring purposes.
            // But the slider needs to still be judged with a reasonable hit/miss result for visual purposes (hit/miss transforms, etc).
            if (HitObject.OnlyJudgeNestedObjects)
            {
                ApplyResult(r => r.Type = NestedHitObjects.Any(h => h.Result.IsHit) ? r.Judgement.MaxResult : r.Judgement.MinResult);
                return;
            }

            // Otherwise, if this slider also needs to be judged, apply judgement proportionally to the number of nested hitobjects hit. This is the classic osu!stable scoring.
            ApplyResult(r =>
            {
                int totalTicks = NestedHitObjects.Count;
                int hitTicks = NestedHitObjects.Count(h => h.IsHit);

                if (hitTicks == totalTicks)
                    r.Type = HitResult.Great;
                else if (hitTicks == 0)
                    r.Type = HitResult.Miss;
                else
                {
                    double hitFraction = (double)hitTicks / totalTicks;
                    r.Type = hitFraction >= 0.5 ? HitResult.Ok : HitResult.Meh;
                }
            });
        }

        public override void PlaySamples()
        {
            // rather than doing it this way, we should probably attach the sample to the tail circle.
            // this can only be done after we stop using LegacyLastTick.
            if (!TailCircle.SamplePlaysOnlyOnHit || TailCircle.IsHit)
                base.PlaySamples();
        }

        protected override void UpdateInitialTransforms()
        {
            base.UpdateInitialTransforms();

            Body.FadeInFromZero(HitObject.TimeFadeIn);
        }

        protected override void UpdateStartTimeStateTransforms()
        {
            base.UpdateStartTimeStateTransforms();

            Ball.FadeIn();
            Ball.ScaleTo(HitObject.Scale);
        }

        protected override void UpdateHitStateTransforms(ArmedState state)
        {
            base.UpdateHitStateTransforms(state);

            const float fade_out_time = 450;

            // intentionally pile on an extra FadeOut to make it happen much faster.
            Ball.FadeOut(fade_out_time / 4, Easing.Out);

            switch (state)
            {
                case ArmedState.Hit:
                    Ball.ScaleTo(HitObject.Scale * 1.4f, fade_out_time, Easing.Out);
                    if (SliderBody?.SnakingOut.Value == true)
                        Body.FadeOut(40); // short fade to allow for any body colour to smoothly disappear.
                    break;
            }

            this.FadeOut(fade_out_time, Easing.OutQuint).Expire();
        }

        public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) => SliderBody?.ReceivePositionalInputAt(screenSpacePos) ?? base.ReceivePositionalInputAt(screenSpacePos);

        private class DefaultSliderBody : PlaySliderBody
        {
        }
    }
}