feat(app): add TextureCache for Surface→GL texture handle caching

src/AcDream.App/Rendering/TextureCache.cs

@@ -0,0 +1,92 @@
+// src/AcDream.App/Rendering/TextureCache.cs
+using AcDream.Core.Textures;
+using DatReaderWriter;
+using DatReaderWriter.DBObjs;
+using Silk.NET.OpenGL;
+
+namespace AcDream.App.Rendering;
+
+public sealed unsafe class TextureCache : IDisposable
+{
+    private readonly GL _gl;
+    private readonly DatCollection _dats;
+    private readonly Dictionary<uint, uint> _handlesBySurfaceId = new();
+    private uint _magentaHandle;
+
+    public TextureCache(GL gl, DatCollection dats)
+    {
+        _gl = gl;
+        _dats = dats;
+    }
+
+    /// <summary>
+    /// Get or upload the GL texture handle for a Surface id. Returns a
+    /// 1x1 magenta fallback if the Surface or its RenderSurface chain is
+    /// missing or uses an unsupported format.
+    /// </summary>
+    public uint GetOrUpload(uint surfaceId)
+    {
+        if (_handlesBySurfaceId.TryGetValue(surfaceId, out var h))
+            return h;
+
+        var decoded = DecodeFromDats(surfaceId);
+        h = UploadRgba8(decoded);
+        _handlesBySurfaceId[surfaceId] = h;
+        return h;
+    }
+
+    private DecodedTexture DecodeFromDats(uint surfaceId)
+    {
+        var surface = _dats.Get<Surface>(surfaceId);
+        if (surface is null)
+            return DecodedTexture.Magenta;
+
+        var surfaceTexture = _dats.Get<SurfaceTexture>((uint)surface.OrigTextureId);
+        if (surfaceTexture is null || surfaceTexture.Textures.Count == 0)
+            return DecodedTexture.Magenta;
+
+        var rs = _dats.Get<RenderSurface>((uint)surfaceTexture.Textures[0]);
+        if (rs is null)
+            return DecodedTexture.Magenta;
+
+        return SurfaceDecoder.DecodeRenderSurface(rs);
+    }
+
+    private uint UploadRgba8(DecodedTexture decoded)
+    {
+        uint tex = _gl.GenTexture();
+        _gl.BindTexture(TextureTarget.Texture2D, tex);
+
+        fixed (byte* p = decoded.Rgba8)
+            _gl.TexImage2D(
+                TextureTarget.Texture2D,
+                0,
+                InternalFormat.Rgba8,
+                (uint)decoded.Width,
+                (uint)decoded.Height,
+                0,
+                PixelFormat.Rgba,
+                PixelType.UnsignedByte,
+                p);
+
+        _gl.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
+        _gl.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
+        _gl.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)TextureWrapMode.Repeat);
+        _gl.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)TextureWrapMode.Repeat);
+
+        _gl.BindTexture(TextureTarget.Texture2D, 0);
+        return tex;
+    }
+
+    public void Dispose()
+    {
+        foreach (var h in _handlesBySurfaceId.Values)
+            _gl.DeleteTexture(h);
+        _handlesBySurfaceId.Clear();
+        if (_magentaHandle != 0)
+        {
+            _gl.DeleteTexture(_magentaHandle);
+            _magentaHandle = 0;
+        }
+    }
+}