OsuDistanceSnapProvider.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.Linq;
using System.Numerics;
using osu.Game.Graphics.UserInterface;
using osu.Game.Input.Bindings;
using osu.Game.Rulesets.Edit;
using osu.Game.Rulesets.Objects;
using osu.Game.Rulesets.Objects.Types;
using osu.Game.Rulesets.Osu.Beatmaps;
using osu.Game.Rulesets.Osu.Objects;

namespace osu.Game.Rulesets.Osu.Edit
{
    public partial class OsuDistanceSnapProvider : ComposerDistanceSnapProvider
    {
        public override double ReadCurrentDistanceSnap(HitObject before, HitObject after)
        {
            // If the pair of hit objects in question here could feasibly be on the same stack, do not provide a distance snap value -
            // they're likely too close to one another for the distance snap value to be useful anyway even if they somehow are not.
            if (Vector2.DistanceSquared(((OsuHitObject)before).EndPosition, ((OsuHitObject)after).Position) < OsuBeatmapProcessor.STACK_DISTANCE * OsuBeatmapProcessor.STACK_DISTANCE)
                return 0;

            var lastObjectWithVelocity = EditorBeatmap.HitObjects.TakeWhile(ho => ho != after).OfType<IHasSliderVelocity>().LastOrDefault();

            float expectedDistance = DurationToDistance(after.StartTime - before.GetEndTime(), before.StartTime, lastObjectWithVelocity);
            float actualDistance = Vector2.Distance(((OsuHitObject)before).StackedEndPosition, ((OsuHitObject)after).StackedPosition);

            return actualDistance / expectedDistance;
        }

        protected override bool AdjustDistanceSpacing(GlobalAction action, float amount)
        {
            // To allow better visualisation, ensure that the spacing grid is visible before adjusting.
            DistanceSnapToggle.Value = TernaryState.True;

            return base.AdjustDistanceSpacing(action, amount);
        }
    }
}