Fix: Re-bind inline constant buffers after update when using compatible SRB

Author: hzqst

Graphics/GraphicsEngineOpenGL/include/PipelineResourceSignatureGLImpl.hpp

@@ -143,7 +143,12 @@ class PipelineResourceSignatureGLImpl final : public PipelineResourceSignatureBa
 
     // Updates inline constant buffers by mapping the shared dynamic UBOs and copying
     // data from the CPU-side staging buffer in the resource cache.
-    void UpdateInlineConstantBuffers(const ShaderResourceCacheGL& ResourceCache, class GLContextState& CtxState) const;
+    // Also re-binds the inline constant buffers to the correct GL slots to ensure
+    // the signature's shared buffers are used even when an SRB from a compatible
+    // but different signature is used.
+    void UpdateInlineConstantBuffers(const ShaderResourceCacheGL& ResourceCache,
+                                     class GLContextState&        CtxState,
+                                     const TBindings&             BaseBindings) const;
 
     bool HasInlineConstants() const
     {

Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp

@@ -756,7 +756,7 @@ void DeviceContextGLImpl::BindProgramResources(Uint32 BindSRBMask, bool DynamicB
             {
                 if (PipelineResourceSignatureGLImpl* pSign = m_pPipelineState->GetResourceSignature(sign))
                 {
-                    pSign->UpdateInlineConstantBuffers(*pResourceCache, GetContextState());
+                    pSign->UpdateInlineConstantBuffers(*pResourceCache, GetContextState(), BaseBindings);
                 }
                 else
                 {

Graphics/GraphicsEngineOpenGL/src/PipelineResourceSignatureGLImpl.cpp

@@ -605,8 +605,12 @@ void PipelineResourceSignatureGLImpl::CopyStaticResources(ShaderResourceCacheGL&
 #endif
 }
 
-void PipelineResourceSignatureGLImpl::UpdateInlineConstantBuffers(const ShaderResourceCacheGL& ResourceCache, GLContextState& CtxState) const
+void PipelineResourceSignatureGLImpl::UpdateInlineConstantBuffers(const ShaderResourceCacheGL& ResourceCache,
+                                                                   GLContextState&              CtxState,
+                                                                   const TBindings&             BaseBindings) const
 {
+    const Uint16 BaseUBOBinding = BaseBindings[BINDING_RANGE_UNIFORM_BUFFER];
+
     for (Uint32 i = 0; i < m_NumInlineConstantBuffers; ++i)
     {
         const InlineConstantBufferAttribsGL& InlineCBAttr = GetInlineConstantBuffer(i);
@@ -616,11 +620,24 @@ void PipelineResourceSignatureGLImpl::UpdateInlineConstantBuffers(const ShaderRe
         VERIFY(InlineCBAttr.NumConstants * sizeof(Uint32) == InlineCB.RangeSize, "Inline constant buffer size mismatch");
         VERIFY(InlineCB.pInlineConstantData != nullptr, "Inline constant data pointer is null");
 
+        const Uint32 BufferSize = InlineCBAttr.NumConstants * sizeof(Uint32);
+
         // Map the shared buffer and copy the data
         PVoid pMappedData = nullptr;
         InlineCBAttr.pBuffer->Map(CtxState, MAP_WRITE, MAP_FLAG_DISCARD, pMappedData);
-        memcpy(pMappedData, InlineCB.pInlineConstantData, InlineCBAttr.NumConstants * sizeof(Uint32));
+        memcpy(pMappedData, InlineCB.pInlineConstantData, BufferSize);
         InlineCBAttr.pBuffer->Unmap(CtxState);
+
+        // Re-bind the signature's shared inline constant buffer to the GL slot.
+        // This is necessary because when an SRB created from a compatible but different
+        // signature is used, the SRB's cache contains buffer pointers to the original
+        // signature's shared buffers. BindResources() binds those buffers, but we need
+        // to bind *this* signature's shared buffers which now contain the updated data.
+        InlineCBAttr.pBuffer->BufferMemoryBarrier(MEMORY_BARRIER_UNIFORM_BUFFER, CtxState);
+        CtxState.BindUniformBuffer(BaseUBOBinding + InlineCBAttr.CacheOffset,
+                                   InlineCBAttr.pBuffer->GetGLHandle(),
+                                   0, // BaseOffset
+                                   BufferSize);
     }
 }