[D3D11] Fixed undefined behavior of UpdateSubresource() on deferred c…

…ommand context (#156). Use UpdateSubresource1() when the destination offset is non-zero or emulate it as described in the MSDN docs: https://learn.microsoft.com/en-us/windows/win32/api/d3d11/nf-d3d11-id3d11devicecontext-updatesubresource#calling-updatesubresource-on-a-deferred-context
LukasBanana · Feb 6, 2025 · 2ae011f · 2ae011f
1 parent 89617e5
commit 2ae011f
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Showing 5 changed files with 38 additions and 5 deletions.
diff --git a/sources/Renderer/Direct3D11/Buffer/D3D11Buffer.cpp b/sources/Renderer/Direct3D11/Buffer/D3D11Buffer.cpp
@@ -84,7 +84,7 @@ BufferDescriptor D3D11Buffer::GetDesc() const
     return bufferDesc;
 }
 
-void D3D11Buffer::WriteSubresource(ID3D11DeviceContext* context, const void* data, UINT dataSize, UINT offset)
+void D3D11Buffer::WriteSubresource(ID3D11DeviceContext* context, const void* data, UINT dataSize, UINT offset, bool needsCommandListEmulation)
 {
     /* Validate parameters */
     LLGL_ASSERT_RANGE(dataSize + offset, GetSize());
@@ -127,7 +127,28 @@ void D3D11Buffer::WriteSubresource(ID3D11DeviceContext* context, const void* dat
         {
             /* Update subresource region of buffer */
             const D3D11_BOX dstBox{ offset, 0, 0, offset + dataSize, 1, 1 };
-            context->UpdateSubresource(GetNative(), 0, &dstBox, data, 0, 0);
+            if (offset != 0 && needsCommandListEmulation && context->GetType() == D3D11_DEVICE_CONTEXT_DEFERRED)
+            {
+                #if LLGL_D3D11_ENABLE_FEATURELEVEL >= 1
+                ComPtr<ID3D11DeviceContext1> context1;
+                if (SUCCEEDED(context->QueryInterface(IID_PPV_ARGS(&context1))))
+                {
+                    /* Update buffer with UpdateSubresource1() which fixes the issue described below */
+                    context1->UpdateSubresource1(GetNative(), 0, &dstBox, data, 0, 0, 0);
+                }
+                else
+                #endif
+                {
+                    /*
+                    Update subresource region of buffer with adjusted source pointer to workaround limitation of emulated command lists.
+                    See https://learn.microsoft.com/en-us/windows/win32/api/d3d11/nf-d3d11-id3d11devicecontext-updatesubresource#calling-updatesubresource-on-a-deferred-context
+                    */
+                    const char* dataWithOffset = static_cast<const char*>(data) - offset;
+                    context->UpdateSubresource(GetNative(), 0, &dstBox, dataWithOffset, 0, 0);
+                }
+            }
+            else
+                context->UpdateSubresource(GetNative(), 0, &dstBox, data, 0, 0);
         }
     }
 }

diff --git a/sources/Renderer/Direct3D11/Buffer/D3D11Buffer.h b/sources/Renderer/Direct3D11/Buffer/D3D11Buffer.h
@@ -34,7 +34,7 @@ class D3D11Buffer : public Buffer
 
         D3D11Buffer(ID3D11Device* device, const BufferDescriptor& desc, const void* initialData = nullptr);
 
-        void WriteSubresource(ID3D11DeviceContext* context, const void* data, UINT dataSize, UINT offset);
+        void WriteSubresource(ID3D11DeviceContext* context, const void* data, UINT dataSize, UINT offset, bool needsCommandListEmulation);
         void ReadSubresource(ID3D11DeviceContext* context, void* data, UINT dataSize, UINT offset);
 
         void* Map(ID3D11DeviceContext* context, const CPUAccess access, UINT offset, UINT length);

diff --git a/sources/Renderer/Direct3D11/Command/D3D11PrimaryCommandBuffer.cpp b/sources/Renderer/Direct3D11/Command/D3D11PrimaryCommandBuffer.cpp
@@ -96,7 +96,8 @@ void D3D11PrimaryCommandBuffer::UpdateBuffer(
     std::uint16_t   dataSize)
 {
     auto& dstBufferD3D = LLGL_CAST(D3D11Buffer&, dstBuffer);
-    dstBufferD3D.WriteSubresource(GetNative(), data, static_cast<UINT>(dataSize), static_cast<UINT>(dstOffset));
+    const bool needsCommandListEmulation = context_.GetStateManager().NeedsCommandListEmulation();
+    dstBufferD3D.WriteSubresource(GetNative(), data, static_cast<UINT>(dataSize), static_cast<UINT>(dstOffset), needsCommandListEmulation);
 }
 
 void D3D11PrimaryCommandBuffer::CopyBuffer(

diff --git a/sources/Renderer/Direct3D11/D3D11RenderSystem.cpp b/sources/Renderer/Direct3D11/D3D11RenderSystem.cpp
@@ -195,7 +195,7 @@ void D3D11RenderSystem::Release(BufferArray& bufferArray)
 void D3D11RenderSystem::WriteBuffer(Buffer& buffer, std::uint64_t offset, const void* data, std::uint64_t dataSize)
 {
     auto& bufferD3D = LLGL_CAST(D3D11Buffer&, buffer);
-    bufferD3D.WriteSubresource(context_.Get(), data, static_cast<UINT>(dataSize), static_cast<UINT>(offset));
+    bufferD3D.WriteSubresource(context_.Get(), data, static_cast<UINT>(dataSize), static_cast<UINT>(offset), stateMngr_->NeedsCommandListEmulation());
 }
 
 void D3D11RenderSystem::ReadBuffer(Buffer& buffer, std::uint64_t offset, void* data, std::uint64_t dataSize)

diff --git a/sources/Renderer/Direct3D11/RenderState/D3D11StateManager.h b/sources/Renderer/Direct3D11/RenderState/D3D11StateManager.h
@@ -110,6 +110,17 @@ class D3D11StateManager
             return bindingTable_;
         }
 
+        // Returns whether the device context this state manager operates on needs command list emulation.
+        // This is true if the D3D device does not natively support command lists.
+        inline bool NeedsCommandListEmulation() const
+        {
+            #if LLGL_D3D11_ENABLE_FEATURELEVEL >= 1
+            return needsCommandListEmulation_;
+            #else
+            return true;
+            #endif
+        }
+
     private:
 
         struct D3DInputAssemblyState