Adjust minimum triangle movement speed to avoid "static" triangles in logo

Closes #14584.

osu.Game.Tests/Visual/UserInterface/TestSceneOsuLogo.cs

@@ -0,0 +1,25 @@
+// 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 NUnit.Framework;
+using osu.Framework.Graphics;
+using osu.Game.Screens.Menu;
+
+namespace osu.Game.Tests.Visual.UserInterface
+{
+    public class TestSceneOsuLogo : OsuTestScene
+    {
+        [Test]
+        public void TestBasic()
+        {
+            AddStep("Add logo", () =>
+            {
+                Child = new OsuLogo
+                {
+                    Anchor = Anchor.Centre,
+                    Origin = Anchor.Centre,
+                };
+            });
+        }
+    }
+}

osu.Game/Graphics/Backgrounds/Triangles.cs

@@ -153,7 +153,7 @@ protected override void Update()
                 TriangleParticle newParticle = parts[i];
 
                 // Scale moved distance by the size of the triangle. Smaller triangles should move more slowly.
-                newParticle.Position.Y += parts[i].Scale * movedDistance;
+                newParticle.Position.Y += Math.Max(0.5f, parts[i].Scale) * movedDistance;
                 newParticle.Colour.A = adjustedAlpha;
 
                 parts[i] = newParticle;