Merge pull request #410 from peppy/general-fixes

Add exponential fall-off of triangles' alpha values.

osu.Desktop.Tests/osu.Desktop.Tests.csproj

@@ -54,9 +54,6 @@
     <Reference Include="SQLite.Net.Platform.Generic">
       <HintPath>$(SolutionDir)\packages\SQLite.Net-PCL.3.1.1\lib\net40\SQLite.Net.Platform.Generic.dll</HintPath>
     </Reference>
-    <Reference Include="OpenTK">
-      <HintPath>$(SolutionDir)\packages\ppy.OpenTK.2.0.50727.1339\lib\net45\OpenTK.dll</HintPath>
-    </Reference>
   </ItemGroup>
   <ItemGroup>
     <Compile Include="BenchmarkTest.cs" />

osu.Game.Modes.Osu/Objects/Drawables/Pieces/TrianglesPiece.cs

@@ -14,6 +14,7 @@ namespace osu.Game.Modes.Osu.Objects.Drawables.Pieces
         public TrianglesPiece()
         {
             TriangleScale = 1.2f;
+            HideAlphaDiscrepancies = false;
         }
 
         protected override void Update()

osu.Game/Graphics/Backgrounds/Triangles.cs

@@ -10,6 +10,7 @@ using osu.Framework.MathUtils;
 using OpenTK;
 using OpenTK.Graphics;
 using System;
+using osu.Framework.Graphics.Colour;
 
 namespace osu.Game.Graphics.Backgrounds
 {
@@ -37,6 +38,13 @@ namespace osu.Game.Graphics.Backgrounds
 
         private float triangleScale = 1;
 
+        /// <summary>
+        /// Whether we should drop-off alpha values of triangles more quickly to improve
+        /// the visual appearance of fading. This defaults to on as it is generally more
+        /// aesthetically pleasing, but should be turned off in <see cref="BufferedContainer{T}"/>s.
+        /// </summary>
+        public bool HideAlphaDiscrepancies = true;
+
         public float TriangleScale
         {
             get { return triangleScale; }
@@ -63,8 +71,14 @@ namespace osu.Game.Graphics.Backgrounds
         {
             base.Update();
 
+            float adjustedAlpha = HideAlphaDiscrepancies ?
+                // Cubically scale alpha to make it drop off more sharply.
+                (float)Math.Pow(DrawInfo.Colour.AverageColour.Linear.A, 3) :
+                1;
+
             foreach (var t in Children)
             {
+                t.Alpha = adjustedAlpha;
                 t.Position -= new Vector2(0, (float)(t.Scale.X * (50 / DrawHeight) * (Time.Elapsed / 950)) / triangleScale);
                 if (ExpireOffScreenTriangles && t.DrawPosition.Y + t.DrawSize.Y * t.Scale.Y < 0)
                     t.Expire();