DrawableHitCircle.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.Collections.Generic;
using System.Diagnostics;
using osu.Framework.Allocation;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Framework.Input.Bindings;
using osu.Framework.Input.Events;
using osu.Framework.Utils;
using osu.Game.Graphics.Containers;
using osu.Game.Rulesets.Judgements;
using osu.Game.Rulesets.Objects.Drawables;
using osu.Game.Rulesets.Osu.Judgements;
using osu.Game.Rulesets.Osu.Skinning;
using osu.Game.Rulesets.Osu.Skinning.Default;
using osu.Game.Rulesets.Osu.UI;
using osu.Game.Rulesets.Scoring;
using osu.Game.Skinning;
using osuTK;
using osuTK.Graphics;

namespace osu.Game.Rulesets.Osu.Objects.Drawables
{
    public partial class DrawableHitCircle : DrawableOsuHitObject, IHasApproachCircle
    {
        public OsuAction? HitAction => HitArea.HitAction;
        protected virtual OsuSkinComponents CirclePieceComponent => OsuSkinComponents.HitCircle;

        public SkinnableDrawable ApproachCircle { get; private set; } = null!;
        public HitReceptor HitArea { get; private set; } = null!;
        public SkinnableDrawable CirclePiece { get; private set; } = null!;

        protected override IEnumerable<Drawable> DimmablePieces => dimmablePieces;
        private Drawable[] dimmablePieces = null!;

        Drawable IHasApproachCircle.ApproachCircle => ApproachCircle;

        private Container scaleContainer = null!;
        private ShakeContainer shakeContainer = null!;

        public DrawableHitCircle()
            : this(null)
        {
        }

        public DrawableHitCircle(HitCircle? h = null)
            : base(h)
        {
        }

        [BackgroundDependencyLoader]
        private void load()
        {
            Origin = Anchor.Centre;

            AddRangeInternal(new Drawable[]
            {
                scaleContainer = new Container
                {
                    RelativeSizeAxes = Axes.Both,
                    Origin = Anchor.Centre,
                    Anchor = Anchor.Centre,
                    Children = new Drawable[]
                    {
                        HitArea = new HitReceptor
                        {
                            CanBeHit = () => !AllJudged,
                            Hit = () => UpdateResult(true)
                        },
                        shakeContainer = new ShakeContainer
                        {
                            ShakeDuration = 30,
                            RelativeSizeAxes = Axes.Both,
                            Children = new Drawable[]
                            {
                                CirclePiece = new SkinnableDrawable(new OsuSkinComponentLookup(CirclePieceComponent), _ => new MainCirclePiece())
                                {
                                    Anchor = Anchor.Centre,
                                    Origin = Anchor.Centre,
                                },
                                ApproachCircle = new ProxyableSkinnableDrawable(new OsuSkinComponentLookup(OsuSkinComponents.ApproachCircle), _ => new DefaultApproachCircle())
                                {
                                    Anchor = Anchor.Centre,
                                    Origin = Anchor.Centre,
                                    RelativeSizeAxes = Axes.Both,
                                    Alpha = 0,
                                    Scale = new Vector2(4),
                                }
                            }
                        }
                    }
                },
            });

            Size = HitArea.DrawSize;

            dimmablePieces = new Drawable[] { CirclePiece };

            PositionBindable.BindValueChanged(_ => UpdatePosition());
            StackHeightBindable.BindValueChanged(_ => UpdatePosition());
            ScaleBindable.BindValueChanged(scale => scaleContainer.Scale = new Vector2(scale.NewValue));
        }

        public override double LifetimeStart
        {
            get => base.LifetimeStart;
            set
            {
                base.LifetimeStart = value;
                ApproachCircle.LifetimeStart = value;
            }
        }

        public override double LifetimeEnd
        {
            get => base.LifetimeEnd;
            set
            {
                base.LifetimeEnd = value;
                ApproachCircle.LifetimeEnd = value;
            }
        }

        protected virtual void UpdatePosition()
        {
            Position = HitObject.StackedPosition;
        }

        public override void Shake() => shakeContainer.Shake();

        protected override void CheckForResult(bool userTriggered, double timeOffset)
        {
            Debug.Assert(HitObject.HitWindows != null);

            if (!userTriggered)
            {
                if (!HitObject.HitWindows.CanBeHit(timeOffset))
                {
                    ApplyResult((r, position) =>
                    {
                        var circleResult = (OsuHitCircleJudgementResult)r;

                        circleResult.Type = r.Judgement.MinResult;
                        circleResult.CursorPositionAtHit = position;
                    }, computeHitPosition());
                }

                return;
            }

            var result = ResultFor(timeOffset);
            var clickAction = CheckHittable?.Invoke(this, Time.Current, result);

            if (clickAction == ClickAction.Shake)
                Shake();

            if (result == HitResult.None || clickAction != ClickAction.Hit)
                return;

            ApplyResult<(HitResult result, Vector2? position)>((r, state) =>
            {
                var circleResult = (OsuHitCircleJudgementResult)r;

                circleResult.Type = state.result;
                circleResult.CursorPositionAtHit = state.position;
            }, (result, computeHitPosition()));
        }

        private Vector2? computeHitPosition()
        {
            if (HitArea.ClosestPressPosition is Vector2 screenSpaceHitPosition)
                return HitObject.StackedPosition + (ToLocalSpace(screenSpaceHitPosition) - DrawSize / 2);

            return null;
        }

        /// <summary>
        /// Retrieves the <see cref="HitResult"/> for a time offset.
        /// </summary>
        /// <param name="timeOffset">The time offset.</param>
        /// <returns>The hit result, or <see cref="HitResult.None"/> if <paramref name="timeOffset"/> doesn't result in a judgement.</returns>
        protected virtual HitResult ResultFor(double timeOffset) => HitObject.HitWindows.ResultFor(timeOffset);

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

            CirclePiece.FadeInFromZero(HitObject.TimeFadeIn);

            ApproachCircle.FadeTo(0.9f, Math.Min(HitObject.TimeFadeIn * 2, HitObject.TimePreempt));
            ApproachCircle.ScaleTo(1f, HitObject.TimePreempt);
            ApproachCircle.Expire(true);
        }

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

            // always fade out at the circle's start time (to match user expectations).
            ApproachCircle.FadeOut(50);
        }

        protected override void UpdateHitStateTransforms(ArmedState state)
        {
            Debug.Assert(HitObject.HitWindows != null);

            // todo: temporary / arbitrary, used for lifetime optimisation.
            this.Delay(800).FadeOut();

            switch (state)
            {
                default:
                    ApproachCircle.FadeOut();
                    break;

                case ArmedState.Idle:
                    HitArea.Reset();
                    break;

                case ArmedState.Miss:
                    this.FadeOut(100);
                    break;
            }

            Expire();
        }

        public Drawable ProxiedLayer => ApproachCircle;

        protected override JudgementResult CreateResult(Judgement judgement) => new OsuHitCircleJudgementResult(HitObject, judgement);

        public partial class HitReceptor : CompositeDrawable, IKeyBindingHandler<OsuAction>
        {
            // IsHovered is used
            public override bool HandlePositionalInput => true;

            /// <summary>
            /// Whether the hitobject can still be hit at the current point in time.
            /// </summary>
            public required Func<bool> CanBeHit { get; set; }

            /// <summary>
            /// An action that's invoked to perform the hit.
            /// </summary>
            public required Action Hit { get; set; }

            /// <summary>
            /// The <see cref="OsuAction"/> with which the hit was attempted.
            /// </summary>
            public OsuAction? HitAction { get; private set; }

            /// <summary>
            /// The closest position to the hit receptor at the point where the hit was attempted.
            /// </summary>
            public Vector2? ClosestPressPosition { get; private set; }

            public HitReceptor()
            {
                Size = OsuHitObject.OBJECT_DIMENSIONS;

                Anchor = Anchor.Centre;
                Origin = Anchor.Centre;

                CornerRadius = OsuHitObject.OBJECT_RADIUS;
                CornerExponent = 2;
            }

            public bool OnPressed(KeyBindingPressEvent<OsuAction> e)
            {
                if (!CanBeHit())
                    return false;

                switch (e.Action)
                {
                    case OsuAction.LeftButton:
                    case OsuAction.RightButton:
                        if (ClosestPressPosition is Vector2 curClosest)
                        {
                            float oldDist = Vector2.DistanceSquared(curClosest, ScreenSpaceDrawQuad.Centre);
                            float newDist = Vector2.DistanceSquared(e.ScreenSpaceMousePosition, ScreenSpaceDrawQuad.Centre);

                            if (newDist < oldDist)
                                ClosestPressPosition = e.ScreenSpaceMousePosition;
                        }
                        else
                            ClosestPressPosition = e.ScreenSpaceMousePosition;

                        if (IsHovered)
                        {
                            Hit();
                            HitAction ??= e.Action;
                            return true;
                        }

                        break;
                }

                return false;
            }

            public void OnReleased(KeyBindingReleaseEvent<OsuAction> e)
            {
            }

            /// <summary>
            /// Resets to a fresh state.
            /// </summary>
            public void Reset()
            {
                HitAction = null;
                ClosestPressPosition = null;
            }
        }

        private partial class ProxyableSkinnableDrawable : SkinnableDrawable
        {
            public override bool RemoveWhenNotAlive => false;

            public ProxyableSkinnableDrawable(ISkinComponentLookup lookup, Func<ISkinComponentLookup, Drawable>? defaultImplementation = null, ConfineMode confineMode = ConfineMode.NoScaling)
                : base(lookup, defaultImplementation, confineMode)
            {
            }
        }

        #region FOR EDITOR USE ONLY, DO NOT USE FOR ANY OTHER PURPOSE

        internal void SuppressHitAnimations()
        {
            UpdateState(ArmedState.Idle);
            UpdateComboColour();

            // This method is called every frame in editor contexts, thus the lack of need for transforms.

            if (Time.Current >= HitStateUpdateTime)
            {
                // More or less matches stable (see https://github.com/peppy/osu-stable-reference/blob/bb57924c1552adbed11ee3d96cdcde47cf96f2b6/osu!/GameplayElements/HitObjects/Osu/HitCircleOsu.cs#L336-L338)
                AccentColour.Value = Color4.White;
                Alpha = Interpolation.ValueAt(Time.Current, 1f, 0f, HitStateUpdateTime, HitStateUpdateTime + 700);
            }

            LifetimeEnd = HitStateUpdateTime + 700;
        }

        internal void RestoreHitAnimations()
        {
            UpdateState(ArmedState.Hit, force: true);
            UpdateComboColour();
        }

        #endregion
    }
}