From bbbf3434aefd105662f9efd4bf9e7d56f9e8170b Mon Sep 17 00:00:00 2001
From: Egor Yusov <egor.yusov@gmail.com>
Date: Sun, 11 Mar 2018 12:07:09 -0700
Subject: Implemented PSO compatibility in D3D11

---
 Graphics/GraphicsEngine/include/DeviceContextBase.h |  8 +++++---
 Graphics/GraphicsEngine/include/PipelineStateBase.h |  8 ++++++++
 Graphics/GraphicsEngine/interface/PipelineState.h   | 16 ++++++++++++++++
 3 files changed, 29 insertions(+), 3 deletions(-)

(limited to 'Graphics/GraphicsEngine')

diff --git a/Graphics/GraphicsEngine/include/DeviceContextBase.h b/Graphics/GraphicsEngine/include/DeviceContextBase.h
index 75e2c109..8099afc7 100644
--- a/Graphics/GraphicsEngine/include/DeviceContextBase.h
+++ b/Graphics/GraphicsEngine/include/DeviceContextBase.h
@@ -97,6 +97,7 @@ public:
     inline virtual void SetPipelineState(IPipelineState *pPipelineState)override = 0;
 
     /// Base implementation of IDeviceContext::CommitShaderResources(); validates parameters.
+    template<typename PSOImplType>
     inline bool CommitShaderResources(IShaderResourceBinding *pShaderResourceBinding, Uint32 Flags, int);
 
     /// Base implementation of IDeviceContext::SetIndexBuffer(); caches the strong reference to the index buffer
@@ -249,6 +250,7 @@ inline void DeviceContextBase<BaseInterface> :: SetPipelineState(IPipelineState
 }
 
 template<typename BaseInterface>
+template<typename PSOImplType>
 inline bool DeviceContextBase<BaseInterface> :: CommitShaderResources(IShaderResourceBinding *pShaderResourceBinding, Uint32 Flags, int)
 {
 #ifdef _DEBUG
@@ -260,10 +262,10 @@ inline bool DeviceContextBase<BaseInterface> :: CommitShaderResources(IShaderRes
 
     if (pShaderResourceBinding)
     {
-        auto *pPSO = pShaderResourceBinding->GetPipelineState();
-        if (pPSO != m_pPipelineState)
+        auto *pPSOImpl = ValidatedCast<PSOImplType>(m_pPipelineState.RawPtr());
+        if (pPSOImpl->IsIncompatibleWith(pShaderResourceBinding->GetPipelineState()))
         {
-            LOG_ERROR_MESSAGE("Shader resource binding object does not match currently bound pipeline state");
+            LOG_ERROR_MESSAGE("Shader resource binding object is not compatible with the currently bound pipeline state");
             return false;
         }
     }
diff --git a/Graphics/GraphicsEngine/include/PipelineStateBase.h b/Graphics/GraphicsEngine/include/PipelineStateBase.h
index a293d575..7348c32c 100644
--- a/Graphics/GraphicsEngine/include/PipelineStateBase.h
+++ b/Graphics/GraphicsEngine/include/PipelineStateBase.h
@@ -173,6 +173,13 @@ public:
     IShader* const* GetShaders()const{return m_ppShaders;}
     Uint32 GetNumShaders()const{return m_NumShaders;}
 
+    // This function only compares shader resource layout hashes, so
+    // it can potentially give false negatives
+    bool IsIncompatibleWith(IPipelineState *pPSO)const
+    {
+        return m_ShaderResourceLayoutHash != ValidatedCast<PipelineStateBase>(pPSO)->m_ShaderResourceLayoutHash;
+    }
+
 protected:
     std::vector<LayoutElement, STDAllocatorRawMem<LayoutElement> > m_LayoutElements;
 
@@ -189,6 +196,7 @@ protected:
     RefCntAutoPtr<IShader> m_pCS; ///< Strong reference to the compute shader
     IShader *m_ppShaders[5];  ///< Array of pointers to shaders that this PSO uses
     Uint32 m_NumShaders; ///< Number of shaders that this PSO uses
+    size_t m_ShaderResourceLayoutHash = 0;///< Hash computed from the shader resource layout
 };
 
 }
diff --git a/Graphics/GraphicsEngine/interface/PipelineState.h b/Graphics/GraphicsEngine/interface/PipelineState.h
index 7e31b49a..58f05f7f 100644
--- a/Graphics/GraphicsEngine/interface/PipelineState.h
+++ b/Graphics/GraphicsEngine/interface/PipelineState.h
@@ -220,6 +220,22 @@ public:
     /// \param [out] ppShaderResourceBinding - memory location where pointer to the new shader resource
     ///                                        binding object is written.
     virtual void CreateShaderResourceBinding( IShaderResourceBinding **ppShaderResourceBinding ) = 0;
+
+    /// Checks if this pipeline state object is compatible with another PSO
+
+    /// If two pipeline state objects are compatible, they can use shader resource binding
+    /// objects interchangebly, i.e. SRBs created by one PSO can be committed
+    /// when another PSO is bound.
+    /// \param [in] pPSO - Pointer to the pipeline state object to check compatibility with
+    /// \return     true if this PSO is compatbile with pPSO. false otherwise.
+    /// \remarks    The function only checks that shader resource layouts are compatible, but 
+    ///             does not check if resource types match. For instance, if a pixel shader in one PSO
+    ///             uses a texture at slot 0, and a pixel shader in another PSO uses texture array at slot 0,
+    ///             the pipelines will be compatible. However, if you try to use SRB object from the first pipeline
+    ///             to commit resources for the second pipeline, a runtime error will occur.\n
+    ///             The function only checks compatibility of shader resource layouts. It does not take
+    ///             into account vertex shader input layout, number of outputs, etc.
+    virtual bool IsCompatibleWith(const IPipelineState *pPSO)const = 0;
 };
 
 }
-- 
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