Add TextureArraySlicer

Penumbra/Interop/Services/TextureArraySlicer.cs

@@ -0,0 +1,119 @@
+using FFXIVClientStructs.FFXIV.Client.Graphics.Kernel;
+using OtterGui.Services;
+using SharpDX.Direct3D;
+using SharpDX.Direct3D11;
+
+namespace Penumbra.Interop.Services;
+
+/// <summary>
+/// Creates ImGui handles over slices of array textures, and manages their lifetime.
+/// </summary>
+public sealed unsafe class TextureArraySlicer : IUiService, IDisposable
+{
+    private const uint InitialTimeToLive = 2;
+
+    private readonly Dictionary<(nint XivTexture, byte SliceIndex), SliceState> _activeSlices = [];
+    private readonly HashSet<(nint XivTexture, byte SliceIndex)>                _expiredKeys  = [];
+
+    /// <remarks> Caching this across frames will cause a crash to desktop. </remarks>
+    public nint GetImGuiHandle(Texture* texture, byte sliceIndex)
+    {
+        if (texture == null)
+            throw new ArgumentNullException(nameof(texture));
+        if (sliceIndex >= texture->ArraySize)
+            throw new ArgumentOutOfRangeException(nameof(sliceIndex), $"Slice index ({sliceIndex}) is greater than or equal to the texture array size ({texture->ArraySize})");
+        if (_activeSlices.TryGetValue(((nint)texture, sliceIndex), out var state))
+        {
+            state.Refresh();
+            return (nint)state.ShaderResourceView;
+        }
+        var srv = (ShaderResourceView)(nint)texture->D3D11ShaderResourceView;
+        var description = srv.Description;
+        switch (description.Dimension)
+        {
+            case ShaderResourceViewDimension.Texture1D:
+            case ShaderResourceViewDimension.Texture2D:
+            case ShaderResourceViewDimension.Texture2DMultisampled:
+            case ShaderResourceViewDimension.Texture3D:
+            case ShaderResourceViewDimension.TextureCube:
+                // This function treats these as single-slice arrays.
+                // As per the range check above, the only valid slice (i. e. 0) has been requested, therefore there is nothing to do.
+                break;
+            case ShaderResourceViewDimension.Texture1DArray:
+                description.Texture1DArray.FirstArraySlice = sliceIndex;
+                description.Texture2DArray.ArraySize = 1;
+                break;
+            case ShaderResourceViewDimension.Texture2DArray:
+                description.Texture2DArray.FirstArraySlice = sliceIndex;
+                description.Texture2DArray.ArraySize = 1;
+                break;
+            case ShaderResourceViewDimension.Texture2DMultisampledArray:
+                description.Texture2DMSArray.FirstArraySlice = sliceIndex;
+                description.Texture2DMSArray.ArraySize = 1;
+                break;
+            case ShaderResourceViewDimension.TextureCubeArray:
+                description.TextureCubeArray.First2DArrayFace = sliceIndex * 6;
+                description.TextureCubeArray.CubeCount = 1;
+                break;
+            default:
+                throw new NotSupportedException($"{nameof(TextureArraySlicer)} does not support dimension {description.Dimension}");
+        }
+        state = new SliceState(new ShaderResourceView(srv.Device, srv.Resource, description));
+        _activeSlices.Add(((nint)texture, sliceIndex), state);
+        return (nint)state.ShaderResourceView;
+    }
+
+    public void Tick()
+    {
+        try
+        {
+            foreach (var (key, slice) in _activeSlices)
+            {
+                if (!slice.Tick())
+                    _expiredKeys.Add(key);
+            }
+            foreach (var key in _expiredKeys)
+            {
+                _activeSlices.Remove(key);
+            }
+        }
+        finally
+        {
+            _expiredKeys.Clear();
+        }
+    }
+
+    public void Dispose()
+    {
+        foreach (var slice in _activeSlices.Values)
+        {
+            slice.Dispose();
+        }
+    }
+
+    private sealed class SliceState(ShaderResourceView shaderResourceView) : IDisposable
+    {
+        public readonly ShaderResourceView ShaderResourceView = shaderResourceView;
+
+        private uint _timeToLive = InitialTimeToLive;
+
+        public void Refresh()
+        {
+            _timeToLive = InitialTimeToLive;
+        }
+
+        public bool Tick()
+        {
+            if (unchecked(_timeToLive--) > 0)
+                return true;
+
+            ShaderResourceView.Dispose();
+            return false;
+        }
+
+        public void Dispose()
+        {
+            ShaderResourceView.Dispose();
+        }
+    }
+}