Tidy up code. Make trail smooth.

osu.Game/Graphics/Cursor/CursorTrail.cs

@@ -0,0 +1,155 @@
+//Copyright (c) 2007-2016 ppy Pty Ltd <contact@ppy.sh>.
+//Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System.Linq;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Batches;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shaders;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Graphics.Textures;
+using osu.Framework.Input;
+using osu.Framework.MathUtils;
+using OpenTK;
+
+namespace osu.Game.Graphics.Cursor
+{
+    class TrailSprite : Sprite
+    {
+        private Shader shader;
+
+        public TrailSprite()
+        {
+            Origin = Anchor.Centre;
+        }
+
+        protected override void ApplyDrawNode(DrawNode node)
+        {
+            base.ApplyDrawNode(node);
+
+            SpriteDrawNode sNode = node as SpriteDrawNode;
+            sNode.RoundedTextureShader = sNode.TextureShader = shader;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(ShaderManager shaders, TextureStore textures)
+        {
+            shader = shaders?.Load(@"CursorTrail", FragmentShaderDescriptor.Texture);
+            Texture = textures.Get(@"Cursor/cursortrail");
+        }
+    }
+
+    class CursorTrail : Container<TrailSprite>
+    {
+        public override bool Contains(Vector2 screenSpacePos) => true;
+
+        int currentIndex;
+
+        protected override bool CanBeFlattened => false;
+
+        Shader shader;
+
+        private double timeOffset;
+
+        private float time;
+
+        const int MAX_SPRITES = 2048;
+
+        protected override DrawNode CreateDrawNode() => new TrailDrawNode();
+
+        protected override void ApplyDrawNode(DrawNode node)
+        {
+            base.ApplyDrawNode(node);
+
+            TrailDrawNode tNode = node as TrailDrawNode;
+            tNode.Shader = shader;
+            tNode.Time = time;
+        }
+
+        Vector2? last;
+
+        protected override bool OnMouseMove(InputState state)
+        {
+            if (last == null)
+            {
+                last = state.Mouse.Position;
+                return base.OnMouseMove(state);
+            }
+
+            Vector2 pos1 = last.Value;
+            Vector2 pos2 = state.Mouse.Position;
+
+            Vector2 diff = (pos2 - pos1);
+            float distance = diff.Length;
+            Vector2 direction = diff / distance;
+
+            float interval = this[0].DrawSize.X / 2;
+
+            for (float d = interval; d < distance; d += interval)
+            {
+                last = pos1 + direction * d;
+                addPosition(last.Value);
+            }
+
+            return base.OnMouseMove(state);
+        }
+
+        private void addPosition(Vector2 pos)
+        {
+            var s = this[currentIndex];
+            s.Position = pos;
+            s.Alpha = time + 1f;
+
+            currentIndex = (currentIndex + 1) % MAX_SPRITES;
+        }
+
+        public CursorTrail()
+        {
+            RelativeSizeAxes = Axes.Both;
+
+            for (int i = 0; i < MAX_SPRITES; i++)
+                AddInternal(new TrailSprite());
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(ShaderManager shaders)
+        {
+            shader = shaders?.Load(@"CursorTrail", FragmentShaderDescriptor.Texture);
+        }
+
+        protected override void Update()
+        {
+            base.Update();
+
+            Invalidate(Invalidation.DrawNode);
+
+            int fadeClockResetThreshold = 1000000;
+
+            time = (float)(Time.Current - timeOffset) / 500f;
+            if (time > fadeClockResetThreshold)
+                ResetTime();
+        }
+
+        private void ResetTime()
+        {
+            foreach (var c in Children)
+                c.Alpha -= time;
+
+            time = 0;
+            timeOffset = Time.Current;
+        }
+
+        class TrailDrawNode : ContainerDrawNode
+        {
+            public Shader Shader;
+            public float Time;
+
+            public override void Draw(IVertexBatch vertexBatch)
+            {
+                Shader.GetUniform<float>("g_FadeClock").Value = Time;
+                base.Draw(vertexBatch);
+            }
+        }
+    }
+}

osu.Game/Graphics/Cursor/OsuCursorContainer.cs

@@ -1,15 +1,22 @@
 //Copyright (c) 2007-2016 ppy Pty Ltd <contact@ppy.sh>.
 //Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
+using System.Collections.Generic;
+using OpenTK;
 using osu.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Cursor;
+using osu.Framework.Graphics.OpenGL;
+using osu.Framework.Graphics.OpenGL.Buffers;
+using osu.Framework.Graphics.Primitives;
 using osu.Framework.Graphics.Sprites;
 using osu.Framework.Graphics.Textures;
 using osu.Framework.Graphics.Transformations;
 using osu.Framework.Input;
+using OpenTK.Graphics;
+using OpenTK.Graphics.ES30;
 
 namespace osu.Game.Graphics.Cursor
 {
@@ -17,9 +24,14 @@ namespace osu.Game.Graphics.Cursor
     {
         protected override Drawable CreateCursor() => new OsuCursor();
 
+        public OsuCursorContainer()
+        {
+            Add(new CursorTrail { Depth = -1 });
+        }
+
         protected override bool OnMouseDown(InputState state, MouseDownEventArgs args)
         {
-            ActiveCursor.Scale = new OpenTK.Vector2(1);
+            ActiveCursor.Scale = new Vector2(1);
             ActiveCursor.ScaleTo(1.2f, 100, EasingTypes.OutQuad);
             return base.OnMouseDown(state, args);
         }
@@ -52,5 +64,4 @@ namespace osu.Game.Graphics.Cursor
             }
         }
     }
-
 }

osu.Game/osu.Game.csproj

@@ -64,6 +64,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Beatmaps\Drawables\BeatmapBackgroundSprite.cs" />
+    <Compile Include="Graphics\Cursor\CursorTrail.cs" />
     <Compile Include="Modes\Objects\HitObjectParser.cs" />
     <Compile Include="Overlays\DragBar.cs" />
     <Compile Include="Overlays\MusicController.cs" />