Merge pull request #9080 from bdach/sequential-scroll-lifetime-start

Fix display start time in sequential scroll algorithm

osu.Game.Tests/ScrollAlgorithms/SequentialScrollTest.cs

@@ -29,8 +29,22 @@ namespace osu.Game.Tests.ScrollAlgorithms
         [Test]
         public void TestDisplayStartTime()
         {
-            // Sequential scroll algorithm approximates the start time
+            // easy cases - time range adjusted for velocity fits within control point duration
-            // This should be fixed in the future
+            Assert.AreEqual(2500, algorithm.GetDisplayStartTime(5000, 0, 2500, 1)); // 5000 - (2500 / 1)
+            Assert.AreEqual(13750, algorithm.GetDisplayStartTime(15000, 0, 2500, 1)); // 15000 - (2500 / 2)
+            Assert.AreEqual(20000, algorithm.GetDisplayStartTime(25000, 0, 2500, 1)); // 25000 - (2500 / 0.5)
+
+            // hard case - time range adjusted for velocity exceeds control point duration
+
+            // 1st multiplier point takes 10000 / 2500 = 4 scroll lengths
+            // 2nd multiplier point takes 10000 / (2500 / 2) = 8 scroll lengths
+            // 3rd multiplier point takes 2500 / (2500 * 2) = 0.5 scroll lengths up to hitobject start
+
+            // absolute position of the hitobject = 1000 * (4 + 8 + 0.5) = 12500
+            // minus one scroll length allowance = 12500 - 1000 = 11500 = 11.5 [scroll lengths]
+            // therefore the start time lies within the second multiplier point (because 11.5 < 4 + 8)
+            // its exact time position is = 10000 + 7.5 * (2500 / 2) = 19375
+            Assert.AreEqual(19375, algorithm.GetDisplayStartTime(22500, 0, 2500, 1000));
         }
 
         [Test]

osu.Game.Tests/Visual/Gameplay/TestSceneScrollingHitObjects.cs

@@ -16,6 +16,7 @@ using osu.Game.Configuration;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
+using osu.Game.Rulesets.Scoring;
 using osu.Game.Rulesets.Timing;
 using osu.Game.Rulesets.UI.Scrolling;
 using osuTK;
@@ -77,19 +78,18 @@ namespace osu.Game.Tests.Visual.Gameplay
                 }
             };
 
-            setUpHitObjects();
+            hitObjectSpawnDelegate?.Cancel();
         });
 
-        private void setUpHitObjects()
+        private void setUpHitObjects() => AddStep("set up hit objects", () =>
         {
             scrollContainers.ForEach(c => c.ControlPoints.Add(new MultiplierControlPoint(0)));
 
             for (int i = spawn_rate / 2; i <= time_range; i += spawn_rate)
                 addHitObject(Time.Current + i);
 
-            hitObjectSpawnDelegate?.Cancel();
             hitObjectSpawnDelegate = Scheduler.AddDelayed(() => addHitObject(Time.Current + time_range), spawn_rate, true);
-        }
+        });
 
         private IList<MultiplierControlPoint> testControlPoints => new List<MultiplierControlPoint>
         {
@@ -101,6 +101,8 @@ namespace osu.Game.Tests.Visual.Gameplay
         [Test]
         public void TestScrollAlgorithms()
         {
+            setUpHitObjects();
+
             AddStep("constant scroll", () => setScrollAlgorithm(ScrollVisualisationMethod.Constant));
             AddStep("overlapping scroll", () => setScrollAlgorithm(ScrollVisualisationMethod.Overlapping));
             AddStep("sequential scroll", () => setScrollAlgorithm(ScrollVisualisationMethod.Sequential));
@@ -113,6 +115,8 @@ namespace osu.Game.Tests.Visual.Gameplay
         [Test]
         public void TestConstantScrollLifetime()
         {
+            setUpHitObjects();
+
             AddStep("set constant scroll", () => setScrollAlgorithm(ScrollVisualisationMethod.Constant));
             // scroll container time range must be less than the rate of spawning hitobjects
             // otherwise the hitobjects will spawn already partly visible on screen and look wrong
@@ -122,14 +126,40 @@ namespace osu.Game.Tests.Visual.Gameplay
         [Test]
         public void TestSequentialScrollLifetime()
         {
+            setUpHitObjects();
+
             AddStep("set sequential scroll", () => setScrollAlgorithm(ScrollVisualisationMethod.Sequential));
             AddStep("set time range", () => scrollContainers.ForEach(c => c.TimeRange = time_range / 2.0));
             AddStep("add control points", () => addControlPoints(testControlPoints, Time.Current));
         }
 
+        [Test]
+        public void TestSlowSequentialScroll()
+        {
+            AddStep("set sequential scroll", () => setScrollAlgorithm(ScrollVisualisationMethod.Sequential));
+            AddStep("set time range", () => scrollContainers.ForEach(c => c.TimeRange = time_range));
+            AddStep("add control points", () => addControlPoints(
+                new List<MultiplierControlPoint>
+                {
+                    new MultiplierControlPoint { Velocity = 0.1 }
+                },
+                Time.Current + time_range));
+
+            // All of the hit objects added below should be immediately visible on screen
+            AddStep("add hit objects", () =>
+            {
+                for (int i = 0; i < 20; ++i)
+                {
+                    addHitObject(Time.Current + time_range * (2 + 0.1 * i));
+                }
+            });
+        }
+
         [Test]
         public void TestOverlappingScrollLifetime()
         {
+            setUpHitObjects();
+
             AddStep("set overlapping scroll", () => setScrollAlgorithm(ScrollVisualisationMethod.Overlapping));
             AddStep("set time range", () => scrollContainers.ForEach(c => c.TimeRange = time_range / 2.0));
             AddStep("add control points", () => addControlPoints(testControlPoints, Time.Current));
@@ -221,7 +251,7 @@ namespace osu.Game.Tests.Visual.Gameplay
         private class TestDrawableControlPoint : DrawableHitObject<HitObject>
         {
             public TestDrawableControlPoint(ScrollingDirection direction, double time)
-                : base(new HitObject { StartTime = time })
+                : base(new HitObject { StartTime = time, HitWindows = HitWindows.Empty })
             {
                 Origin = Anchor.Centre;
 
@@ -252,7 +282,7 @@ namespace osu.Game.Tests.Visual.Gameplay
         private class TestDrawableHitObject : DrawableHitObject<HitObject>
         {
             public TestDrawableHitObject(double time)
-                : base(new HitObject { StartTime = time })
+                : base(new HitObject { StartTime = time, HitWindows = HitWindows.Empty })
             {
                 Origin = Anchor.Custom;
                 OriginPosition = new Vector2(75 / 4.0f);

osu.Game/Rulesets/UI/Scrolling/Algorithms/SequentialScrollAlgorithm.cs

@@ -22,8 +22,7 @@ namespace osu.Game.Rulesets.UI.Scrolling.Algorithms
 
         public double GetDisplayStartTime(double originTime, float offset, double timeRange, float scrollLength)
         {
-            double adjustedTime = TimeAt(-offset, originTime, timeRange, scrollLength);
+            return TimeAt(-(scrollLength + offset), originTime, timeRange, scrollLength);
-            return adjustedTime - timeRange - 1000;
         }
 
         public float GetLength(double startTime, double endTime, double timeRange, float scrollLength)