fix: Vulkan: honor stage-declared read-only depth access on worker command lists

Author: xen2

sources/engine/Stride.Graphics/CommandList.cs

@@ -52,6 +52,14 @@ public partial class CommandList : GraphicsResourceBase
         /// </summary>
         public int ViewportCount => boundViewportCount;
 
+        /// <summary>
+        ///   Gets how draws access the currently bound Depth-Stencil Buffer.
+        ///   Part of the binding: reset to <see cref="DepthStencilAccess.Write"/> by any
+        ///   <c>SetRenderTargets</c> call.
+        ///   Stopgap until render pass objects declare this per pass.
+        /// </summary>
+        internal DepthStencilAccess DepthStencilAccess { get; set; }
+
 
         /// <summary>
         ///   Binds a single viewport to the rasterizer stage of the pipeline.
@@ -238,6 +246,7 @@ public void ResetTargets()
             ResetTargetsImpl();
 
             depthStencilBuffer = null;
+            DepthStencilAccess = DepthStencilAccess.Write;
             renderTargets.AsSpan().Clear();
         }
 
@@ -260,6 +269,7 @@ public void ResetTargets()
         public void SetRenderTargetAndViewport(Texture depthStencilView, Texture renderTargetView)
         {
             depthStencilBuffer = depthStencilView;
+            DepthStencilAccess = DepthStencilAccess.Write;
 
             renderTargets[0] = renderTargetView;  // TODO: Should we clear the other entries?
             renderTargetCount = renderTargetView is not null ? 1 : 0;
@@ -286,6 +296,7 @@ public void SetRenderTargetAndViewport(Texture depthStencilView, Texture renderT
         public void SetRenderTargetsAndViewport(ReadOnlySpan<Texture> renderTargetViews)
         {
             depthStencilBuffer = null;
+            DepthStencilAccess = DepthStencilAccess.Write;
 
             renderTargetCount = renderTargetViews.Length;
             renderTargetViews.CopyTo(renderTargets);
@@ -315,6 +326,7 @@ public void SetRenderTargetsAndViewport(ReadOnlySpan<Texture> renderTargetViews)
         public void SetRenderTargetsAndViewport(Texture depthStencilView, params ReadOnlySpan<Texture> renderTargetViews)
         {
             depthStencilBuffer = depthStencilView;
+            DepthStencilAccess = DepthStencilAccess.Write;
 
             renderTargetCount = renderTargetViews.Length;
             renderTargetViews.CopyTo(renderTargets);  // TODO: Should we clear the other entries?
@@ -340,6 +352,7 @@ public void SetRenderTargetsAndViewport(Texture depthStencilView, params ReadOnl
         public void SetRenderTarget(Texture depthStencilView, Texture renderTargetView)
         {
             depthStencilBuffer = depthStencilView;
+            DepthStencilAccess = DepthStencilAccess.Write;
 
             renderTargetCount = renderTargetView is not null ? 1 : 0;
             renderTargets[0] = renderTargetView;  // TODO: Should we clear the other entries?
@@ -367,6 +380,7 @@ public void SetRenderTargets(ReadOnlySpan<Texture> renderTargetViews)
             ArgumentOutOfRangeException.ThrowIfGreaterThan(renderTargetViews.Length, MaxRenderTargetCount);
 
             depthStencilBuffer = null;
+            DepthStencilAccess = DepthStencilAccess.Write;
 
             renderTargetCount = renderTargetViews.Length;
             renderTargetViews.CopyTo(renderTargets);  // TODO: Should we clear the other entries?
@@ -397,6 +411,7 @@ public void SetRenderTargets(Texture depthStencilView, params ReadOnlySpan<Textu
             ArgumentOutOfRangeException.ThrowIfGreaterThan(renderTargetViews.Length, MaxRenderTargetCount);
 
             depthStencilBuffer = depthStencilView;
+            DepthStencilAccess = DepthStencilAccess.Write;
 
             renderTargetCount = renderTargetViews.Length;
             renderTargetViews.CopyTo(renderTargets);  // TODO: Should we clear the other entries?
@@ -482,6 +497,8 @@ public void ClearState()
         {
             ClearStateImpl();
 
+            DepthStencilAccess = DepthStencilAccess.Write;
+
             // Setup empty viewports
             Array.Clear(viewports);
 

sources/engine/Stride.Graphics/DepthStencilAccess.cs

@@ -0,0 +1,21 @@
+// Copyright (c) .NET Foundation and Contributors (https://dotnetfoundation.org/ & https://stride3d.net)
+// Distributed under the MIT license. See the LICENSE.md file in the project root for more information.
+
+namespace Stride.Graphics;
+
+/// <summary>
+///   Defines how draws access the bound Depth-Stencil Buffer.
+/// </summary>
+internal enum DepthStencilAccess
+{
+    /// <summary>
+    ///   Depth and stencil writes are allowed.
+    /// </summary>
+    Write,
+
+    /// <summary>
+    ///   Read-only: the buffer can be depth-tested and sampled at the same time.
+    ///   Depth and stencil writes are dropped.
+    /// </summary>
+    Read,
+}

sources/engine/Stride.Graphics/Vulkan/CommandList.Vulkan.cs

@@ -281,7 +281,7 @@ private unsafe void PrepareDraw()
             // A read-only depth view drops depth and stencil writes instead of being invalid
             // usage, matching D3D12's read-only depth-stencil view behavior
             var depthStencilState = activePipeline.Description.DepthStencilState;
-            bool depthWritesAllowed = depthStencilBuffer?.IsDepthStencilReadOnly != true;
+            bool depthWritesAllowed = !(depthStencilBuffer != null && (depthStencilBuffer.IsDepthStencilReadOnly || DepthStencilAccess == DepthStencilAccess.Read));
             GraphicsDevice.NativeDeviceApi.vkCmdSetDepthWriteEnable(currentCommandList.NativeCommandBuffer, depthStencilState.DepthBufferWriteEnable && depthWritesAllowed);
             GraphicsDevice.NativeDeviceApi.vkCmdSetStencilWriteMask(currentCommandList.NativeCommandBuffer, VkStencilFaceFlags.FrontAndBack, depthWritesAllowed ? depthStencilState.StencilWriteMask : 0u);
         }
@@ -384,7 +384,8 @@ private unsafe void BindDescriptorSets()
                             // Sampling the depth buffer while it is bound as a read-only attachment:
                             // the image rides in DepthStencilReadOnlyOptimal, including on worker
                             // command lists that did not record the transition themselves.
-                            bool sampledBoundReadOnlyDepth = depthStencilBuffer?.IsDepthStencilReadOnly == true
+                            bool sampledBoundReadOnlyDepth = depthStencilBuffer != null
+                                && (depthStencilBuffer.IsDepthStencilReadOnly || DepthStencilAccess == DepthStencilAccess.Read)
                                 && parent == (depthStencilBuffer.ParentTexture ?? depthStencilBuffer);
                             var imageLayout = perCb == BarrierLayout.DepthStencilRead || (perCb == null && sampledBoundReadOnlyDepth)
                                 ? VkImageLayout.DepthStencilReadOnlyOptimal
@@ -1654,9 +1655,10 @@ private unsafe void EnsureRenderPass()
             if (activePipeline == null || activePipeline.NativePipeline == VkPipeline.Null)
                 return;
 
-            // The depth attachment layout follows the bound view: a read-only depth view keeps the
-            // image in DepthStencilReadOnlyOptimal so it can be sampled at the same time
-            bool depthReadOnly = depthStencilBuffer?.IsDepthStencilReadOnly == true;
+            // The depth attachment layout follows the bound view and the declared stage access:
+            // a read-only depth keeps the image in DepthStencilReadOnlyOptimal so it can be
+            // sampled at the same time
+            bool depthReadOnly = depthStencilBuffer != null && (depthStencilBuffer.IsDepthStencilReadOnly || DepthStencilAccess == DepthStencilAccess.Read);
 
             // The render pass instance stays active across pipeline changes as long as the
             // attachments and the depth layout stay the same

sources/engine/Stride.Rendering/Rendering/RenderSystem.cs

@@ -447,6 +447,14 @@ public void Draw(RenderDrawContext renderDrawContext, RenderView renderView, Ren
                             : BarrierLayout.DepthStencilWrite);
                 }
 
+                // Let command lists know the depth buffer stays readable during this stage, so the
+                // depth attachment layout and descriptors can declare it (e.g. sampling the depth
+                // while it stays bound)
+                var depthStencilAccess = stageDepthAccess == RenderStageDepthAccess.Read
+                    ? DepthStencilAccess.Read
+                    : DepthStencilAccess.Write;
+                commandList.DepthStencilAccess = depthStencilAccess;
+
                 // Collect one command list per batch and the main one up to this point
                 if (commandLists == null || (commandLists.Length < batchCount + 1))
                 {
@@ -465,6 +473,7 @@ public void Draw(RenderDrawContext renderDrawContext, RenderView renderView, Ren
                     threadContext.CommandList.SetRenderTargets(depthStencilBuffer, renderTargetsToSet);
                     threadContext.CommandList.SetViewport(viewport);
                     threadContext.CommandList.SetScissorRectangle(scissor);
+                    threadContext.CommandList.DepthStencilAccess = depthStencilAccess;
 
                     var currentStart = batchSize * batchIndex;
                     int currentEnd;