From 7ecf81d3a0c4e5a9b8ae791823b4ca4720fa19f3 Mon Sep 17 00:00:00 2001
From: marvin <minetoblend@gmail.com>
Date: Wed, 4 Jun 2025 19:58:04 +0200
Subject: [PATCH] Add ghost drawable

---
 .../UserInterface/TestSceneGhostIcon.cs       |  22 +++
 osu.Game/Graphics/GhostIcon.cs                | 130 ++++++++++++++++++
 2 files changed, 152 insertions(+)
 create mode 100644 osu.Game.Tests/Visual/UserInterface/TestSceneGhostIcon.cs
 create mode 100644 osu.Game/Graphics/GhostIcon.cs

diff --git a/osu.Game.Tests/Visual/UserInterface/TestSceneGhostIcon.cs b/osu.Game.Tests/Visual/UserInterface/TestSceneGhostIcon.cs
new file mode 100644
index 0000000000..5ae46d0224
--- /dev/null
+++ b/osu.Game.Tests/Visual/UserInterface/TestSceneGhostIcon.cs
@@ -0,0 +1,22 @@
+// 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 osu.Framework.Graphics;
+using osu.Game.Graphics;
+using osuTK;
+
+namespace osu.Game.Tests.Visual.UserInterface
+{
+    public partial class TestSceneGhostIcon : OsuTestScene
+    {
+        public TestSceneGhostIcon()
+        {
+            Add(new GhostIcon
+            {
+                Size = new Vector2(64),
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+            });
+        }
+    }
+}
diff --git a/osu.Game/Graphics/GhostIcon.cs b/osu.Game/Graphics/GhostIcon.cs
new file mode 100644
index 0000000000..e72359219c
--- /dev/null
+++ b/osu.Game/Graphics/GhostIcon.cs
@@ -0,0 +1,130 @@
+// 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 System.Runtime.InteropServices;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Primitives;
+using osu.Framework.Graphics.Rendering;
+using osu.Framework.Graphics.Rendering.Vertices;
+using osu.Framework.Graphics.Shaders;
+using osu.Framework.Graphics.Shaders.Types;
+using osuTK;
+
+namespace osu.Game.Graphics
+{
+    public partial class GhostIcon : Drawable
+    {
+        private IShader ghostShader = null!;
+
+        [BackgroundDependencyLoader]
+        private void load(ShaderManager shaders)
+        {
+            ghostShader = shaders.Load(VertexShaderDescriptor.TEXTURE_2, "Ghost");
+        }
+
+        protected override void Update()
+        {
+            base.Update();
+
+            Invalidate(Invalidation.DrawNode);
+        }
+
+        protected override DrawNode CreateDrawNode() => new GhostIconDrawNode(this);
+
+        private class GhostIconDrawNode : DrawNode
+        {
+            protected new GhostIcon Source => (GhostIcon)base.Source;
+
+            public GhostIconDrawNode(IDrawable source)
+                : base(source)
+            {
+            }
+
+            private Quad screenSpaceDrawQuad;
+            private Vector4 drawRectangle;
+            private Vector2 blend;
+            private IShader shader = null!;
+            private float time;
+
+            public override void ApplyState()
+            {
+                base.ApplyState();
+
+                screenSpaceDrawQuad = Source.ScreenSpaceDrawQuad;
+                drawRectangle = new Vector4(0, 0, Source.DrawWidth, Source.DrawHeight);
+                shader = Source.ghostShader;
+                blend = new Vector2(Math.Min(Source.DrawWidth, Source.DrawHeight) / Math.Min(screenSpaceDrawQuad.Width, screenSpaceDrawQuad.Height));
+                time = (float)(Source.Time.Current % 1000f) * 0.0005f;
+            }
+
+            private IUniformBuffer<GhostParameters>? ghostParametersBuffer;
+
+            private IVertexBatch<TexturedVertex2D>? quadBatch;
+
+            protected override void Draw(IRenderer renderer)
+            {
+                base.Draw(renderer);
+
+                if (!renderer.BindTexture(renderer.WhitePixel))
+                    return;
+
+                quadBatch ??= renderer.CreateQuadBatch<TexturedVertex2D>(1, 2);
+                ghostParametersBuffer ??= renderer.CreateUniformBuffer<GhostParameters>();
+
+                ghostParametersBuffer.Data = new GhostParameters
+                {
+                    Time = time
+                };
+
+                shader.Bind();
+                shader.BindUniformBlock("m_GhostParameters", ghostParametersBuffer);
+
+                var vertexAction = quadBatch.AddAction;
+
+                vertexAction(new TexturedVertex2D(renderer)
+                {
+                    Position = screenSpaceDrawQuad.BottomLeft,
+                    TexturePosition = new Vector2(0, 1),
+                    TextureRect = drawRectangle,
+                    BlendRange = blend,
+                    Colour = DrawColourInfo.Colour.BottomLeft.SRGB,
+                });
+                vertexAction(new TexturedVertex2D(renderer)
+                {
+                    Position = screenSpaceDrawQuad.BottomRight,
+                    TexturePosition = new Vector2(1, 1),
+                    TextureRect = drawRectangle,
+                    BlendRange = blend,
+                    Colour = DrawColourInfo.Colour.BottomRight.SRGB,
+                });
+                vertexAction(new TexturedVertex2D(renderer)
+                {
+                    Position = screenSpaceDrawQuad.TopRight,
+                    TexturePosition = new Vector2(1, 0),
+                    TextureRect = drawRectangle,
+                    BlendRange = blend,
+                    Colour = DrawColourInfo.Colour.TopRight.SRGB,
+                });
+                vertexAction(new TexturedVertex2D(renderer)
+                {
+                    Position = screenSpaceDrawQuad.TopLeft,
+                    TexturePosition = Vector2.Zero,
+                    TextureRect = drawRectangle,
+                    BlendRange = blend,
+                    Colour = DrawColourInfo.Colour.TopLeft.SRGB,
+                });
+
+                shader.Unbind();
+            }
+
+            [StructLayout(LayoutKind.Sequential, Pack = 1)]
+            private record struct GhostParameters
+            {
+                public UniformFloat Time;
+                private UniformPadding12 pad;
+            }
+        }
+    }
+}