Initial implementation of osu! beat snapping grid

osu.Game.Rulesets.Osu.Tests/TestSceneOsuBeatSnapGrid.cs

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+// 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 NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Shapes;
+using osu.Framework.Graphics.UserInterface;
+using osu.Framework.Input.Events;
+using osu.Game.Beatmaps;
+using osu.Game.Beatmaps.ControlPoints;
+using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Osu.Beatmaps;
+using osu.Game.Rulesets.Osu.Objects;
+using osu.Game.Screens.Edit;
+using osu.Game.Screens.Edit.Compose.Components;
+using osu.Game.Tests.Visual;
+using osuTK;
+using osuTK.Graphics;
+
+namespace osu.Game.Rulesets.Osu.Tests
+{
+    public class TestSceneOsuBeatSnapGrid : ManualInputManagerTestScene
+    {
+        private const double beat_length = 100;
+        private static readonly Vector2 grid_position = new Vector2(512, 384);
+
+        [Cached(typeof(IEditorBeatmap))]
+        private readonly EditorBeatmap<OsuHitObject> editorBeatmap;
+
+        [Cached]
+        private readonly BindableBeatDivisor beatDivisor = new BindableBeatDivisor();
+
+        private OsuBeatSnapGrid grid;
+        private Drawable cursor;
+
+        public TestSceneOsuBeatSnapGrid()
+        {
+            editorBeatmap = new EditorBeatmap<OsuHitObject>(new OsuBeatmap());
+        }
+
+        [SetUp]
+        public void Setup() => Schedule(() =>
+        {
+            Clear();
+
+            editorBeatmap.ControlPointInfo.TimingPoints.Clear();
+            editorBeatmap.ControlPointInfo.TimingPoints.Add(new TimingControlPoint { BeatLength = beat_length });
+
+            beatDivisor.Value = 1;
+        });
+
+        protected override bool OnMouseMove(MouseMoveEvent e)
+        {
+            base.OnMouseMove(e);
+
+            if (cursor != null)
+                cursor.Position = grid?.GetSnapPosition(grid.ToLocalSpace(e.ScreenSpaceMousePosition)) ?? e.ScreenSpaceMousePosition;
+
+            return true;
+        }
+
+        [TestCase(1)]
+        [TestCase(2)]
+        [TestCase(3)]
+        [TestCase(4)]
+        [TestCase(6)]
+        [TestCase(8)]
+        [TestCase(12)]
+        [TestCase(16)]
+        public void TestBeatDivisor(int divisor)
+        {
+            AddStep($"set beat divisor = {divisor}", () => beatDivisor.Value = divisor);
+            createGrid();
+        }
+
+        private void createGrid()
+        {
+            AddStep("create grid", () =>
+            {
+                Children = new Drawable[]
+                {
+                    new Box
+                    {
+                        RelativeSizeAxes = Axes.Both,
+                        Colour = Color4.SlateGray
+                    },
+                    grid = new OsuBeatSnapGrid(new HitCircle { Position = grid_position }),
+                    cursor = new Circle
+                    {
+                        Origin = Anchor.Centre,
+                        Size = new Vector2(50),
+                        Colour = Color4.Red
+                    }
+                };
+            });
+        }
+
+        private abstract class CircularBeatSnapGrid : BeatSnapGrid
+        {
+            protected override void CreateGrid(Vector2 startPosition)
+            {
+                float maxDistance = Math.Max(
+                    Vector2.Distance(startPosition, Vector2.Zero),
+                    Math.Max(
+                        Vector2.Distance(startPosition, new Vector2(DrawWidth, 0)),
+                        Math.Max(
+                            Vector2.Distance(startPosition, new Vector2(0, DrawHeight)),
+                            Vector2.Distance(startPosition, DrawSize))));
+
+                int requiredCircles = (int)(maxDistance / DistanceSpacing);
+
+                for (int i = 0; i < requiredCircles; i++)
+                {
+                    float radius = (i + 1) * DistanceSpacing * 2;
+
+                    AddInternal(new CircularProgress
+                    {
+                        Origin = Anchor.Centre,
+                        Position = startPosition,
+                        Current = { Value = 1 },
+                        Size = new Vector2(radius),
+                        InnerRadius = 4 * 1f / radius,
+                        Colour = GetColourForBeatIndex(i)
+                    });
+                }
+            }
+
+            public override Vector2 GetSnapPosition(Vector2 position)
+            {
+                Vector2 direction = position - StartPosition;
+                float distance = direction.Length;
+
+                float radius = DistanceSpacing;
+                int radialCount = Math.Max(1, (int)Math.Round(distance / radius));
+
+                if (radialCount <= 0)
+                    return position;
+
+                Vector2 normalisedDirection = direction * new Vector2(1f / distance);
+
+                return StartPosition + normalisedDirection * radialCount * radius;
+            }
+        }
+
+        private class OsuBeatSnapGrid : CircularBeatSnapGrid
+        {
+            /// <summary>
+            /// Scoring distance with a speed-adjusted beat length of 1 second.
+            /// </summary>
+            private const float base_scoring_distance = 100;
+
+            public OsuBeatSnapGrid(OsuHitObject hitObject)
+                : base(hitObject, hitObject.StackedEndPosition)
+            {
+            }
+
+            protected override float GetVelocity(double time, ControlPointInfo controlPointInfo, BeatmapDifficulty difficulty)
+            {
+                TimingControlPoint timingPoint = controlPointInfo.TimingPointAt(time);
+                DifficultyControlPoint difficultyPoint = controlPointInfo.DifficultyPointAt(time);
+
+                double scoringDistance = base_scoring_distance * difficulty.SliderMultiplier * difficultyPoint.SpeedMultiplier;
+
+                return (float)(scoringDistance / timingPoint.BeatLength);
+            }
+        }
+    }
+}