Merge branch 'master' into mesh_shader

# Conflicts:
#	Graphics/GraphicsEngine/include/PipelineStateBase.hpp
#	Graphics/GraphicsEngine/interface/PipelineState.h
#	Graphics/GraphicsEngineD3D11/src/DeviceContextD3D11Impl.cpp
#	Graphics/GraphicsEngineD3D12/include/CommandContext.hpp

12 files changed, 680 insertions, 129 deletions

diff --git a/Graphics/GraphicsEngineOpenGL/CMakeLists.txt b/Graphics/GraphicsEngineOpenGL/CMakeLists.txt
index 1072d067..76c51a8c 100644
--- a/Graphics/GraphicsEngineOpenGL/CMakeLists.txt
+++ b/Graphics/GraphicsEngineOpenGL/CMakeLists.txt
@@ -9,6 +9,7 @@ set(INCLUDE
     include/DeviceContextGLImpl.hpp 
     include/FBOCache.hpp
     include/FenceGLImpl.hpp
+    include/FramebufferGLImpl.hpp
     include/GLContext.hpp
     include/GLContextState.hpp
     include/GLObjectWrapper.hpp
@@ -20,6 +21,7 @@ set(INCLUDE
     include/PipelineStateGLImpl.hpp
     include/QueryGLImpl.hpp
     include/RenderDeviceGLImpl.hpp
+    include/RenderPassGLImpl.hpp
     include/SamplerGLImpl.hpp
     include/ShaderGLImpl.hpp
     include/ShaderResourceBindingGLImpl.hpp
@@ -62,6 +64,7 @@ set(SOURCE
     src/EngineFactoryOpenGL.cpp
     src/FBOCache.cpp
     src/FenceGLImpl.cpp
+    src/FramebufferGLImpl.cpp
     src/GLContextState.cpp
     src/GLObjectWrapper.cpp
     src/GLProgramResourceCache.cpp
@@ -71,6 +74,7 @@ set(SOURCE
     src/PipelineStateGLImpl.cpp
     src/QueryGLImpl.cpp
     src/RenderDeviceGLImpl.cpp
+    src/RenderPassGLImpl.cpp
     src/SamplerGLImpl.cpp
     src/ShaderGLImpl.cpp
     src/ShaderResourceBindingGLImpl.cpp
diff --git a/Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp b/Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp
index 54eff631..205c62b7 100644
--- a/Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp
+++ b/Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp
@@ -27,6 +27,8 @@
 
 #pragma once
 
+#include <vector>
+
 #include "DeviceContextGL.h"
 #include "DeviceContextBase.hpp"
 #include "BaseInterfacesGL.h"
@@ -35,6 +37,8 @@
 #include "BufferGLImpl.hpp"
 #include "TextureBaseGL.hpp"
 #include "QueryGLImpl.hpp"
+#include "FramebufferGLImpl.hpp"
+#include "RenderPassGLImpl.hpp"
 #include "PipelineStateGLImpl.hpp"
 
 namespace Diligent
@@ -47,6 +51,8 @@ struct DeviceContextGLImplTraits
     using PipelineStateType = PipelineStateGLImpl;
     using DeviceType        = RenderDeviceGLImpl;
     using QueryType         = QueryGLImpl;
+    using FramebufferType   = FramebufferGLImpl;
+    using RenderPassType    = RenderPassGLImpl;
 };
 
 /// Device context implementation in OpenGL backend.
@@ -110,6 +116,15 @@ public:
                                                      ITextureView*                  pDepthStencil,
                                                      RESOURCE_STATE_TRANSITION_MODE StateTransitionMode) override final;
 
+    /// Implementation of IDeviceContext::BeginRenderPass() in Direct3D11 backend.
+    virtual void DILIGENT_CALL_TYPE BeginRenderPass(const BeginRenderPassAttribs& Attribs) override final;
+
+    /// Implementation of IDeviceContext::NextSubpass() in Direct3D11 backend.
+    virtual void DILIGENT_CALL_TYPE NextSubpass() override final;
+
+    /// Implementation of IDeviceContext::EndRenderPass() in Direct3D11 backend.
+    virtual void DILIGENT_CALL_TYPE EndRenderPass() override final;
+
     // clang-format off
 
     /// Implementation of IDeviceContext::Draw() in OpenGL backend.
@@ -255,6 +270,9 @@ private:
     __forceinline void PrepareForIndirectDraw(IBuffer* pAttribsBuffer);
     __forceinline void PostDraw();
 
+    void BeginSubpass();
+    void EndSubpass();
+
     Uint32 m_CommitedResourcesTentativeBarriers = 0;
 
     std::vector<class TextureBaseGL*> m_BoundWritableTextures;
@@ -265,6 +283,8 @@ private:
     bool m_IsDefaultFBOBound = false;
 
     GLObjectWrappers::GLFrameBufferObj m_DefaultFBO;
+
+    std::vector<OptimizedClearValue> m_AttachmentClearValues;
 };
 
 } // namespace Diligent
diff --git a/Graphics/GraphicsEngineOpenGL/include/FBOCache.hpp b/Graphics/GraphicsEngineOpenGL/include/FBOCache.hpp
index 98e097d2..928da3f8 100644
--- a/Graphics/GraphicsEngineOpenGL/include/FBOCache.hpp
+++ b/Graphics/GraphicsEngineOpenGL/include/FBOCache.hpp
@@ -51,6 +51,11 @@ public:
     FBOCache& operator = (      FBOCache&&) = delete;
     // clang-format on
 
+    static GLObjectWrappers::GLFrameBufferObj CreateFBO(class GLContextState& ContextState,
+                                                        Uint32                NumRenderTargets,
+                                                        TextureViewGLImpl*    ppRTVs[],
+                                                        TextureViewGLImpl*    pDSV);
+
     const GLObjectWrappers::GLFrameBufferObj& GetFBO(Uint32                NumRenderTargets,
                                                      TextureViewGLImpl*    ppRTVs[],
                                                      TextureViewGLImpl*    pDSV,
@@ -91,7 +96,7 @@ private:
 
     // Multimap that sets up correspondence between unique texture id and all
     // FBOs it is used in
-    std::unordered_multimap<Diligent::UniqueIdentifier, FBOCacheKey> m_TexIdToKey;
+    std::unordered_multimap<UniqueIdentifier, FBOCacheKey> m_TexIdToKey;
 };
 
 } // namespace Diligent
diff --git a/Graphics/GraphicsEngineOpenGL/include/FramebufferGLImpl.hpp b/Graphics/GraphicsEngineOpenGL/include/FramebufferGLImpl.hpp
new file mode 100644
index 00000000..49ea8b84
--- /dev/null
+++ b/Graphics/GraphicsEngineOpenGL/include/FramebufferGLImpl.hpp
@@ -0,0 +1,78 @@
+/*
+ *  Copyright 2019-2020 Diligent Graphics LLC
+ *  Copyright 2015-2019 Egor Yusov
+ *  
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *  
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  In no event and under no legal theory, whether in tort (including negligence), 
+ *  contract, or otherwise, unless required by applicable law (such as deliberate 
+ *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
+ *  liable for any damages, including any direct, indirect, special, incidental, 
+ *  or consequential damages of any character arising as a result of this License or 
+ *  out of the use or inability to use the software (including but not limited to damages 
+ *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
+ *  all other commercial damages or losses), even if such Contributor has been advised 
+ *  of the possibility of such damages.
+ */
+
+#pragma once
+
+/// \file
+/// Declaration of Diligent::FramebufferGLImpl class
+
+#include <vector>
+
+#include "RenderDeviceGL.h"
+#include "FramebufferBase.hpp"
+#include "RenderDeviceGLImpl.hpp"
+#include "GLObjectWrapper.hpp"
+
+namespace Diligent
+{
+
+class FixedBlockMemoryAllocator;
+
+/// Render pass implementation in Direct3D11 backend.
+class FramebufferGLImpl final : public FramebufferBase<IFramebuffer, RenderDeviceGLImpl>
+{
+public:
+    using TFramebufferBase = FramebufferBase<IFramebuffer, RenderDeviceGLImpl>;
+
+    FramebufferGLImpl(IReferenceCounters*    pRefCounters,
+                      RenderDeviceGLImpl*    pDevice,
+                      GLContextState&        CtxState,
+                      const FramebufferDesc& Desc);
+    ~FramebufferGLImpl();
+
+    struct SubpassFramebuffers
+    {
+        SubpassFramebuffers(GLObjectWrappers::GLFrameBufferObj&& _RenderTarget,
+                            GLObjectWrappers::GLFrameBufferObj&& _Resolve) :
+            RenderTarget{std::move(_RenderTarget)},
+            Resolve{std::move(_Resolve)}
+        {}
+
+        GLObjectWrappers::GLFrameBufferObj RenderTarget;
+        GLObjectWrappers::GLFrameBufferObj Resolve;
+    };
+
+    const SubpassFramebuffers& GetSubpassFramebuffer(Uint32 subpass)
+    {
+        return m_SubpassFramebuffers[subpass];
+    }
+
+private:
+    std::vector<SubpassFramebuffers> m_SubpassFramebuffers;
+};
+
+} // namespace Diligent
diff --git a/Graphics/GraphicsEngineOpenGL/include/RenderDeviceGLImpl.hpp b/Graphics/GraphicsEngineOpenGL/include/RenderDeviceGLImpl.hpp
index 310faaf6..dbdb51c8 100644
--- a/Graphics/GraphicsEngineOpenGL/include/RenderDeviceGLImpl.hpp
+++ b/Graphics/GraphicsEngineOpenGL/include/RenderDeviceGLImpl.hpp
@@ -113,6 +113,14 @@ public:
     /// Implementation of IRenderDevice::CreateQuery() in OpenGL backend.
     virtual void DILIGENT_CALL_TYPE CreateQuery(const QueryDesc& Desc, IQuery** ppQuery) override final;
 
+    /// Implementation of IRenderDevice::CreateRenderPass() in OpenGL backend.
+    virtual void DILIGENT_CALL_TYPE CreateRenderPass(const RenderPassDesc& Desc,
+                                                     IRenderPass**         ppRenderPass) override final;
+
+    /// Implementation of IRenderDevice::CreateFramebuffer() in OpenGL backend.
+    virtual void DILIGENT_CALL_TYPE CreateFramebuffer(const FramebufferDesc& Desc,
+                                                      IFramebuffer**         ppFramebuffer) override final;
+
     /// Implementation of IRenderDeviceGL::CreateTextureFromGLHandle().
     virtual void DILIGENT_CALL_TYPE CreateTextureFromGLHandle(Uint32             GLHandle,
                                                               Uint32             GLBindTarget,
diff --git a/Graphics/GraphicsEngineOpenGL/include/RenderPassGLImpl.hpp b/Graphics/GraphicsEngineOpenGL/include/RenderPassGLImpl.hpp
new file mode 100644
index 00000000..e5d77333
--- /dev/null
+++ b/Graphics/GraphicsEngineOpenGL/include/RenderPassGLImpl.hpp
@@ -0,0 +1,54 @@
+/*
+ *  Copyright 2019-2020 Diligent Graphics LLC
+ *  Copyright 2015-2019 Egor Yusov
+ *  
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *  
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  In no event and under no legal theory, whether in tort (including negligence), 
+ *  contract, or otherwise, unless required by applicable law (such as deliberate 
+ *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
+ *  liable for any damages, including any direct, indirect, special, incidental, 
+ *  or consequential damages of any character arising as a result of this License or 
+ *  out of the use or inability to use the software (including but not limited to damages 
+ *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
+ *  all other commercial damages or losses), even if such Contributor has been advised 
+ *  of the possibility of such damages.
+ */
+
+#pragma once
+
+/// \file
+/// Declaration of Diligent::RenderPassGLImpl class
+
+#include "RenderDeviceGL.h"
+#include "RenderPassBase.hpp"
+#include "RenderDeviceGLImpl.hpp"
+
+namespace Diligent
+{
+
+class FixedBlockMemoryAllocator;
+
+/// Render pass implementation in Direct3D11 backend.
+class RenderPassGLImpl final : public RenderPassBase<IRenderPass, RenderDeviceGLImpl>
+{
+public:
+    using TRenderPassBase = RenderPassBase<IRenderPass, RenderDeviceGLImpl>;
+
+    RenderPassGLImpl(IReferenceCounters*   pRefCounters,
+                     RenderDeviceGLImpl*   pDevice,
+                     const RenderPassDesc& Desc);
+    ~RenderPassGLImpl();
+};
+
+} // namespace Diligent
diff --git a/Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp b/Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp
index 7728de7b..d7a95033 100644
--- a/Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp
+++ b/Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp
@@ -147,6 +147,11 @@ void DeviceContextGLImpl::SetPipelineState(IPipelineState* pPipelineState)
 
 void DeviceContextGLImpl::TransitionShaderResources(IPipelineState* pPipelineState, IShaderResourceBinding* pShaderResourceBinding)
 {
+    if (m_pActiveRenderPass)
+    {
+        LOG_ERROR_MESSAGE("State transitions are not allowed inside a render pass.");
+        return;
+    }
 }
 
 void DeviceContextGLImpl::CommitShaderResources(IShaderResourceBinding* pShaderResourceBinding, RESOURCE_STATE_TRANSITION_MODE StateTransitionMode)
@@ -250,10 +255,10 @@ void DeviceContextGLImpl::SetViewports(Uint32 NumViewports, const Viewport* pVie
             // https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glViewportIndexed.xhtml
             glViewportIndexedf(0, BottomLeftX, BottomLeftY, vp.Width, vp.Height);
         }
-        CHECK_GL_ERROR("Failed to set viewport");
+        DEV_CHECK_GL_ERROR("Failed to set viewport");
 
         glDepthRangef(vp.MinDepth, vp.MaxDepth);
-        CHECK_GL_ERROR("Failed to set depth range");
+        DEV_CHECK_GL_ERROR("Failed to set depth range");
     }
     else
     {
@@ -263,9 +268,9 @@ void DeviceContextGLImpl::SetViewports(Uint32 NumViewports, const Viewport* pVie
             float       BottomLeftY = static_cast<float>(RTHeight) - (vp.TopLeftY + vp.Height);
             float       BottomLeftX = vp.TopLeftX;
             glViewportIndexedf(i, BottomLeftX, BottomLeftY, vp.Width, vp.Height);
-            CHECK_GL_ERROR("Failed to set viewport #", i);
+            DEV_CHECK_GL_ERROR("Failed to set viewport #", i);
             glDepthRangef(vp.MinDepth, vp.MaxDepth);
-            CHECK_GL_ERROR("Failed to set depth range for viewport #", i);
+            DEV_CHECK_GL_ERROR("Failed to set depth range for viewport #", i);
         }
     }
 }
@@ -296,7 +301,7 @@ void DeviceContextGLImpl::SetScissorRects(Uint32 NumRects, const Rect* pRects, U
         auto width  = Rect.right - Rect.left;
         auto height = Rect.bottom - Rect.top;
         glScissor(Rect.left, glBottom, width, height);
-        CHECK_GL_ERROR("Failed to set scissor rect");
+        DEV_CHECK_GL_ERROR("Failed to set scissor rect");
     }
     else
     {
@@ -307,7 +312,7 @@ void DeviceContextGLImpl::SetScissorRects(Uint32 NumRects, const Rect* pRects, U
             auto        width    = Rect.right - Rect.left;
             auto        height   = Rect.bottom - Rect.top;
             glScissorIndexed(sr, Rect.left, glBottom, width, height);
-            CHECK_GL_ERROR("Failed to set scissor rect #", sr);
+            DEV_CHECK_GL_ERROR("Failed to set scissor rect #", sr);
         }
     }
 }
@@ -319,6 +324,8 @@ void DeviceContextGLImpl::SetSwapChain(ISwapChainGL* pSwapChain)
 
 void DeviceContextGLImpl::CommitRenderTargets()
 {
+    VERIFY(m_pActiveRenderPass == nullptr, "This method must not be called inside render pass");
+
     if (!m_IsDefaultFBOBound && m_NumBoundRenderTargets == 0 && !m_pBoundDepthStencil)
         return;
 
@@ -327,7 +334,7 @@ void DeviceContextGLImpl::CommitRenderTargets()
         GLuint DefaultFBOHandle = m_pSwapChain->GetDefaultFBO();
         if (m_DefaultFBO != DefaultFBOHandle)
         {
-            m_DefaultFBO = GLObjectWrappers::GLFrameBufferObj(true, GLObjectWrappers::GLFBOCreateReleaseHelper(DefaultFBOHandle));
+            m_DefaultFBO = GLObjectWrappers::GLFrameBufferObj{true, GLObjectWrappers::GLFBOCreateReleaseHelper(DefaultFBOHandle)};
         }
         m_ContextState.BindFBO(m_DefaultFBO);
     }
@@ -373,6 +380,14 @@ void DeviceContextGLImpl::SetRenderTargets(Uint32                         NumRen
                                            ITextureView*                  pDepthStencil,
                                            RESOURCE_STATE_TRANSITION_MODE StateTransitionMode)
 {
+#ifdef DILIGENT_DEVELOPMENT
+    if (m_pActiveRenderPass != nullptr)
+    {
+        LOG_ERROR_MESSAGE("Calling SetRenderTargets inside active render pass is invalid. End the render pass first");
+        return;
+    }
+#endif
+
     if (TDeviceContextBase::SetRenderTargets(NumRenderTargets, ppRenderTargets, pDepthStencil))
     {
         if (m_NumBoundRenderTargets == 1 && m_pBoundRenderTargets[0] && m_pBoundRenderTargets[0]->GetTexture<TextureBaseGL>()->GetGLHandle() == 0)
@@ -403,6 +418,140 @@ void DeviceContextGLImpl::ResetRenderTargets()
     m_ContextState.InvalidateFBO();
 }
 
+void DeviceContextGLImpl::BeginSubpass()
+{
+    VERIFY_EXPR(m_pActiveRenderPass);
+    VERIFY_EXPR(m_pBoundFramebuffer);
+    const auto& RPDesc = m_pActiveRenderPass->GetDesc();
+    VERIFY_EXPR(m_SubpassIndex < RPDesc.SubpassCount);
+    const auto& SubpassDesc = RPDesc.pSubpasses[m_SubpassIndex];
+    const auto& FBDesc      = m_pBoundFramebuffer->GetDesc();
+
+    const auto& RenderTargetFBO = m_pBoundFramebuffer->GetSubpassFramebuffer(m_SubpassIndex).RenderTarget;
+    if (RenderTargetFBO != 0)
+    {
+        m_ContextState.BindFBO(RenderTargetFBO);
+    }
+    else
+    {
+        GLuint DefaultFBOHandle = m_pSwapChain->GetDefaultFBO();
+        if (m_DefaultFBO != DefaultFBOHandle)
+        {
+            m_DefaultFBO = GLObjectWrappers::GLFrameBufferObj{true, GLObjectWrappers::GLFBOCreateReleaseHelper(DefaultFBOHandle)};
+        }
+        m_ContextState.BindFBO(m_DefaultFBO);
+    }
+
+    for (Uint32 rt = 0; rt < SubpassDesc.RenderTargetAttachmentCount; ++rt)
+    {
+        const auto& RTAttachmentRef = SubpassDesc.pRenderTargetAttachments[rt];
+        if (RTAttachmentRef.AttachmentIndex != ATTACHMENT_UNUSED)
+        {
+            auto* const pRTV = ValidatedCast<TextureViewGLImpl>(FBDesc.ppAttachments[RTAttachmentRef.AttachmentIndex]);
+            if (pRTV == nullptr)
+                continue;
+
+            auto* const pColorTexGL = pRTV->GetTexture<TextureBaseGL>();
+            pColorTexGL->TextureMemoryBarrier(
+                GL_FRAMEBUFFER_BARRIER_BIT, // Reads and writes via framebuffer object attachments after the
+                                            // barrier will reflect data written by shaders prior to the barrier.
+                                            // Additionally, framebuffer writes issued after the barrier will wait
+                                            // on the completion of all shader writes issued prior to the barrier.
+                m_ContextState);
+
+            const auto& AttachmentDesc = RPDesc.pAttachments[RTAttachmentRef.AttachmentIndex];
+            auto        FirstLastUse   = m_pActiveRenderPass->GetAttachmentFirstLastUse(RTAttachmentRef.AttachmentIndex);
+            if (FirstLastUse.first == m_SubpassIndex && AttachmentDesc.LoadOp == ATTACHMENT_LOAD_OP_CLEAR)
+            {
+                ClearRenderTarget(pRTV, m_AttachmentClearValues[RTAttachmentRef.AttachmentIndex].Color, RESOURCE_STATE_TRANSITION_MODE_NONE);
+            }
+        }
+    }
+
+    if (SubpassDesc.pDepthStencilAttachment != nullptr)
+    {
+        const auto DepthAttachmentIndex = SubpassDesc.pDepthStencilAttachment->AttachmentIndex;
+        if (DepthAttachmentIndex != ATTACHMENT_UNUSED)
+        {
+            auto* const pDSV = ValidatedCast<TextureViewGLImpl>(FBDesc.ppAttachments[DepthAttachmentIndex]);
+            if (pDSV != nullptr)
+            {
+                auto* pDepthTexGL = pDSV->GetTexture<TextureBaseGL>();
+                pDepthTexGL->TextureMemoryBarrier(GL_FRAMEBUFFER_BARRIER_BIT, m_ContextState);
+
+                const auto& AttachmentDesc = RPDesc.pAttachments[DepthAttachmentIndex];
+                auto        FirstLastUse   = m_pActiveRenderPass->GetAttachmentFirstLastUse(DepthAttachmentIndex);
+                if (FirstLastUse.first == m_SubpassIndex && AttachmentDesc.LoadOp == ATTACHMENT_LOAD_OP_CLEAR)
+                {
+                    const auto& ClearVal = m_AttachmentClearValues[DepthAttachmentIndex].DepthStencil;
+                    ClearDepthStencil(pDSV, CLEAR_DEPTH_FLAG | CLEAR_STENCIL_FLAG, ClearVal.Depth, ClearVal.Stencil, RESOURCE_STATE_TRANSITION_MODE_NONE);
+                }
+            }
+        }
+    }
+}
+
+void DeviceContextGLImpl::EndSubpass()
+{
+    VERIFY_EXPR(m_pActiveRenderPass);
+    VERIFY_EXPR(m_pBoundFramebuffer);
+    const auto& RPDesc = m_pActiveRenderPass->GetDesc();
+    VERIFY_EXPR(m_SubpassIndex < RPDesc.SubpassCount);
+    const auto& SubpassDesc = RPDesc.pSubpasses[m_SubpassIndex];
+    if (SubpassDesc.pResolveAttachments != nullptr)
+    {
+        const auto& SubpassFBOs = m_pBoundFramebuffer->GetSubpassFramebuffer(m_SubpassIndex);
+
+        glBindFramebuffer(GL_READ_FRAMEBUFFER, SubpassFBOs.RenderTarget);
+        DEV_CHECK_GL_ERROR("Failed to bind subpass render target FBO as read framebuffer");
+
+        GLuint ResolveDstFBO = SubpassFBOs.Resolve;
+        if (ResolveDstFBO == 0)
+        {
+            ResolveDstFBO = m_pSwapChain.RawPtr<ISwapChainGL>()->GetDefaultFBO();
+        }
+        glBindFramebuffer(GL_DRAW_FRAMEBUFFER, ResolveDstFBO);
+        DEV_CHECK_GL_ERROR("Failed to bind resolve destination FBO as draw framebuffer");
+
+        const auto& FBODesc = m_pBoundFramebuffer->GetDesc();
+        glBlitFramebuffer(0, 0, static_cast<GLint>(FBODesc.Width), static_cast<GLint>(FBODesc.Height),
+                          0, 0, static_cast<GLint>(FBODesc.Width), static_cast<GLint>(FBODesc.Height),
+                          GL_COLOR_BUFFER_BIT,
+                          GL_NEAREST // Filter is ignored
+        );
+        DEV_CHECK_GL_ERROR("glBlitFramebuffer() failed when resolving multi-sampled attachments");
+    }
+    m_ContextState.InvalidateFBO();
+}
+
+void DeviceContextGLImpl::BeginRenderPass(const BeginRenderPassAttribs& Attribs)
+{
+    TDeviceContextBase::BeginRenderPass(Attribs);
+
+    m_AttachmentClearValues.resize(Attribs.ClearValueCount);
+    for (Uint32 i = 0; i < Attribs.ClearValueCount; ++i)
+        m_AttachmentClearValues[i] = Attribs.pClearValues[i];
+
+    VERIFY_EXPR(m_pBoundFramebuffer);
+
+    SetViewports(1, nullptr, 0, 0);
+
+    BeginSubpass();
+}
+
+void DeviceContextGLImpl::NextSubpass()
+{
+    EndSubpass();
+    TDeviceContextBase::NextSubpass();
+    BeginSubpass();
+}
+
+void DeviceContextGLImpl::EndRenderPass()
+{
+    EndSubpass();
+    TDeviceContextBase::EndRenderPass();
+    m_ContextState.InvalidateFBO();
+}
 
 void DeviceContextGLImpl::BindProgramResources(Uint32& NewMemoryBarriers, IShaderResourceBinding* pResBinding)
 {
@@ -524,7 +673,7 @@ void DeviceContextGLImpl::BindProgramResources(Uint32& NewMemoryBarriers, IShade
                 m_ContextState.BindTexture(-1, pTexViewGL->GetBindTarget(), pTexViewGL->GetHandle());
                 GLint IsImmutable = 0;
                 glGetTexParameteriv(pTexViewGL->GetBindTarget(), GL_TEXTURE_IMMUTABLE_FORMAT, &IsImmutable);
-                CHECK_GL_ERROR("glGetTexParameteriv() failed");
+                DEV_CHECK_GL_ERROR("glGetTexParameteriv() failed");
                 VERIFY(IsImmutable, "Only immutable textures can be bound to pipeline using glBindImageTexture()");
                 m_ContextState.BindTexture(-1, pTexViewGL->GetBindTarget(), GLObjectWrappers::GLTextureObj::Null());
             }
@@ -893,7 +1042,7 @@ void DeviceContextGLImpl::DispatchCompute(const DispatchComputeAttribs& Attribs)
 #if GL_ARB_compute_shader
     m_pPipelineState->CommitProgram(m_ContextState);
     glDispatchCompute(Attribs.ThreadGroupCountX, Attribs.ThreadGroupCountY, Attribs.ThreadGroupCountZ);
-    CHECK_GL_ERROR("glDispatchCompute() failed");
+    DEV_CHECK_GL_ERROR("glDispatchCompute() failed");
 
     PostDraw();
 #else
@@ -920,10 +1069,10 @@ void DeviceContextGLImpl::DispatchComputeIndirect(const DispatchComputeIndirectA
 
     constexpr bool ResetVAO = false; // GL_DISPATCH_INDIRECT_BUFFER does not affect VAO
     m_ContextState.BindBuffer(GL_DISPATCH_INDIRECT_BUFFER, pBufferGL->m_GlBuffer, ResetVAO);
-    CHECK_GL_ERROR("Failed to bind a buffer for dispatch indirect command");
+    DEV_CHECK_GL_ERROR("Failed to bind a buffer for dispatch indirect command");
 
     glDispatchComputeIndirect(Attribs.DispatchArgsByteOffset);
-    CHECK_GL_ERROR("glDispatchComputeIndirect() failed");
+    DEV_CHECK_GL_ERROR("glDispatchComputeIndirect() failed");
 
     m_ContextState.BindBuffer(GL_DISPATCH_INDIRECT_BUFFER, GLObjectWrappers::GLBufferObj::Null(), ResetVAO);
 
@@ -969,7 +1118,7 @@ void DeviceContextGLImpl::ClearDepthStencil(ITextureView*                  pView
     // blend function, logical operation, stenciling, texture mapping, and depth-buffering
     // are ignored by glClear.
     glClear(glClearFlags);
-    CHECK_GL_ERROR("glClear() failed");
+    DEV_CHECK_GL_ERROR("glClear() failed");
     m_ContextState.EnableDepthWrites(DepthWritesEnabled);
     m_ContextState.EnableScissorTest(ScissorTestEnabled);
 }
@@ -982,8 +1131,6 @@ void DeviceContextGLImpl::ClearRenderTarget(ITextureView* pView, const float* RG
     VERIFY_EXPR(pView != nullptr);
 
     Int32 RTIndex = -1;
-    VERIFY(pView->GetDesc().ViewType == TEXTURE_VIEW_RENDER_TARGET, "Incorrect view type: render target is expected");
-    CHECK_DYNAMIC_TYPE(TextureViewGLImpl, pView);
     for (Uint32 rt = 0; rt < m_NumBoundRenderTargets; ++rt)
     {
         if (m_pBoundRenderTargets[rt] == pView)
@@ -1022,7 +1169,7 @@ void DeviceContextGLImpl::ClearRenderTarget(ITextureView* pView, const float* RG
     m_ContextState.SetColorWriteMask(RTIndex, COLOR_MASK_ALL, bIndependentBlend);
 
     glClearBufferfv(GL_COLOR, RTIndex, RGBA);
-    CHECK_GL_ERROR("glClearBufferfv() failed");
+    DEV_CHECK_GL_ERROR("glClearBufferfv() failed");
 
     m_ContextState.SetColorWriteMask(RTIndex, WriteMask, bIndependentBlend);
     m_ContextState.EnableScissorTest(ScissorTestEnabled);
@@ -1030,6 +1177,11 @@ void DeviceContextGLImpl::ClearRenderTarget(ITextureView* pView, const float* RG
 
 void DeviceContextGLImpl::Flush()
 {
+    if (m_pActiveRenderPass != nullptr)
+    {
+        LOG_ERROR_MESSAGE("Flushing device context inside an active render pass.");
+    }
+
     glFlush();
 }
 
@@ -1054,7 +1206,7 @@ void DeviceContextGLImpl::SignalFence(IFence* pFence, Uint64 Value)
         GL_SYNC_GPU_COMMANDS_COMPLETE, // Condition must always be GL_SYNC_GPU_COMMANDS_COMPLETE
         0                              // Flags, must be 0
         )};
-    CHECK_GL_ERROR("Failed to create gl fence");
+    DEV_CHECK_GL_ERROR("Failed to create gl fence");
     auto* pFenceGLImpl = ValidatedCast<FenceGLImpl>(pFence);
     pFenceGLImpl->AddPendingFence(std::move(GLFence), Value);
 }
@@ -1087,7 +1239,7 @@ void DeviceContextGLImpl::BeginQuery(IQuery* pQuery)
         case QUERY_TYPE_OCCLUSION:
 #if GL_SAMPLES_PASSED
             glBeginQuery(GL_SAMPLES_PASSED, glQuery);
-            CHECK_GL_ERROR("Failed to begin GL_SAMPLES_PASSED query");
+            DEV_CHECK_GL_ERROR("Failed to begin GL_SAMPLES_PASSED query");
 #else
             LOG_ERROR_MESSAGE_ONCE("GL_SAMPLES_PASSED query is not supported by this device");
 #endif
@@ -1095,13 +1247,13 @@ void DeviceContextGLImpl::BeginQuery(IQuery* pQuery)
 
         case QUERY_TYPE_BINARY_OCCLUSION:
             glBeginQuery(GL_ANY_SAMPLES_PASSED, glQuery);
-            CHECK_GL_ERROR("Failed to begin GL_ANY_SAMPLES_PASSED query");
+            DEV_CHECK_GL_ERROR("Failed to begin GL_ANY_SAMPLES_PASSED query");
             break;
 
         case QUERY_TYPE_PIPELINE_STATISTICS:
 #if GL_PRIMITIVES_GENERATED
             glBeginQuery(GL_PRIMITIVES_GENERATED, glQuery);
-            CHECK_GL_ERROR("Failed to begin GL_PRIMITIVES_GENERATED query");
+            DEV_CHECK_GL_ERROR("Failed to begin GL_PRIMITIVES_GENERATED query");
 #else
             LOG_ERROR_MESSAGE_ONCE("GL_PRIMITIVES_GENERATED query is not supported by this device");
 #endif
@@ -1124,26 +1276,26 @@ void DeviceContextGLImpl::EndQuery(IQuery* pQuery)
         case QUERY_TYPE_OCCLUSION:
 #if GL_SAMPLES_PASSED
             glEndQuery(GL_SAMPLES_PASSED);
-            CHECK_GL_ERROR("Failed to end GL_SAMPLES_PASSED query");
+            DEV_CHECK_GL_ERROR("Failed to end GL_SAMPLES_PASSED query");
 #endif
             break;
 
         case QUERY_TYPE_BINARY_OCCLUSION:
             glEndQuery(GL_ANY_SAMPLES_PASSED);
-            CHECK_GL_ERROR("Failed to end GL_ANY_SAMPLES_PASSED query");
+            DEV_CHECK_GL_ERROR("Failed to end GL_ANY_SAMPLES_PASSED query");
             break;
 
         case QUERY_TYPE_PIPELINE_STATISTICS:
 #if GL_PRIMITIVES_GENERATED
             glEndQuery(GL_PRIMITIVES_GENERATED);
-            CHECK_GL_ERROR("Failed to end GL_PRIMITIVES_GENERATED query");
+            DEV_CHECK_GL_ERROR("Failed to end GL_PRIMITIVES_GENERATED query");
 #endif
             break;
 
         case QUERY_TYPE_TIMESTAMP:
 #if GL_ARB_timer_query
             glQueryCounter(pQueryGLImpl->GetGlQueryHandle(), GL_TIMESTAMP);
-            CHECK_GL_ERROR("glQueryCounter failed");
+            DEV_CHECK_GL_ERROR("glQueryCounter failed");
 #else
             LOG_ERROR_MESSAGE_ONCE("Timer queries are not supported by this device");
 #endif
@@ -1383,12 +1535,13 @@ void DeviceContextGLImpl::GenerateMips(ITextureView* pTexView)
     auto  BindTarget = pTexViewGL->GetBindTarget();
     m_ContextState.BindTexture(-1, BindTarget, pTexViewGL->GetHandle());
     glGenerateMipmap(BindTarget);
-    CHECK_GL_ERROR("Failed to generate mip maps");
+    DEV_CHECK_GL_ERROR("Failed to generate mip maps");
     m_ContextState.BindTexture(-1, BindTarget, GLObjectWrappers::GLTextureObj::Null());
 }
 
 void DeviceContextGLImpl::TransitionResourceStates(Uint32 BarrierCount, StateTransitionDesc* pResourceBarriers)
 {
+    VERIFY(m_pActiveRenderPass == nullptr, "State transitions are not allowed inside a render pass");
 }
 
 void DeviceContextGLImpl::ResolveTextureSubresource(ITexture*                               pSrcTexture,
diff --git a/Graphics/GraphicsEngineOpenGL/src/FBOCache.cpp b/Graphics/GraphicsEngineOpenGL/src/FBOCache.cpp
index 5d18a955..e11a3af2 100644
--- a/Graphics/GraphicsEngineOpenGL/src/FBOCache.cpp
+++ b/Graphics/GraphicsEngineOpenGL/src/FBOCache.cpp
@@ -109,6 +109,116 @@ void FBOCache::OnReleaseTexture(ITexture* pTexture)
     m_TexIdToKey.erase(EqualRange.first, EqualRange.second);
 }
 
+GLObjectWrappers::GLFrameBufferObj FBOCache::CreateFBO(GLContextState&    ContextState,
+                                                       Uint32             NumRenderTargets,
+                                                       TextureViewGLImpl* ppRTVs[],
+                                                       TextureViewGLImpl* pDSV)
+{
+    GLObjectWrappers::GLFrameBufferObj FBO{true};
+
+    ContextState.BindFBO(FBO);
+
+    // Initialize the FBO
+    for (Uint32 rt = 0; rt < NumRenderTargets; ++rt)
+    {
+        if (auto* pRTView = ppRTVs[rt])
+        {
+            const auto& RTVDesc     = pRTView->GetDesc();
+            auto*       pColorTexGL = pRTView->GetTexture<TextureBaseGL>();
+            pColorTexGL->AttachToFramebuffer(RTVDesc, GL_COLOR_ATTACHMENT0 + rt);
+        }
+    }
+
+    if (pDSV != nullptr)
+    {
+        const auto& DSVDesc         = pDSV->GetDesc();
+        auto*       pDepthTexGL     = pDSV->GetTexture<TextureBaseGL>();
+        GLenum      AttachmentPoint = 0;
+        if (DSVDesc.Format == TEX_FORMAT_D32_FLOAT ||
+            DSVDesc.Format == TEX_FORMAT_D16_UNORM)
+        {
+#ifdef DILIGENT_DEBUG
+            {
+                const auto GLTexFmt = pDepthTexGL->GetGLTexFormat();
+                VERIFY(GLTexFmt == GL_DEPTH_COMPONENT32F || GLTexFmt == GL_DEPTH_COMPONENT16,
+                       "Inappropriate internal texture format (", GLTexFmt,
+                       ") for depth attachment. GL_DEPTH_COMPONENT32F or GL_DEPTH_COMPONENT16 is expected");
+            }
+#endif
+            AttachmentPoint = GL_DEPTH_ATTACHMENT;
+        }
+        else if (DSVDesc.Format == TEX_FORMAT_D32_FLOAT_S8X24_UINT ||
+                 DSVDesc.Format == TEX_FORMAT_D24_UNORM_S8_UINT)
+        {
+#ifdef DILIGENT_DEBUG
+            {
+                const auto GLTexFmt = pDepthTexGL->GetGLTexFormat();
+                VERIFY(GLTexFmt == GL_DEPTH24_STENCIL8 || GLTexFmt == GL_DEPTH32F_STENCIL8,
+                       "Inappropriate internal texture format (", GLTexFmt,
+                       ") for depth-stencil attachment. GL_DEPTH24_STENCIL8 or GL_DEPTH32F_STENCIL8 is expected");
+            }
+#endif
+            AttachmentPoint = GL_DEPTH_STENCIL_ATTACHMENT;
+        }
+        else
+        {
+            UNEXPECTED(GetTextureFormatAttribs(DSVDesc.Format).Name, " is not valid depth-stencil view format");
+        }
+        pDepthTexGL->AttachToFramebuffer(DSVDesc, AttachmentPoint);
+    }
+
+    // We now need to set mapping between shader outputs and
+    // color attachments. This largely redundant step is performed
+    // by glDrawBuffers()
+    // clang-format off
+    static const GLenum DrawBuffers[] = 
+    { 
+        GL_COLOR_ATTACHMENT0, 
+        GL_COLOR_ATTACHMENT1, 
+        GL_COLOR_ATTACHMENT2, 
+        GL_COLOR_ATTACHMENT3,
+        GL_COLOR_ATTACHMENT4,
+        GL_COLOR_ATTACHMENT5,
+        GL_COLOR_ATTACHMENT6,
+        GL_COLOR_ATTACHMENT7,
+        GL_COLOR_ATTACHMENT8,
+        GL_COLOR_ATTACHMENT9,
+        GL_COLOR_ATTACHMENT10,
+        GL_COLOR_ATTACHMENT11,
+        GL_COLOR_ATTACHMENT12,
+        GL_COLOR_ATTACHMENT13,
+        GL_COLOR_ATTACHMENT14,
+        GL_COLOR_ATTACHMENT15
+    };
+    // clang-format on
+
+    // The state set by glDrawBuffers() is part of the state of the framebuffer.
+    // So it can be set up once and left it set.
+    glDrawBuffers(NumRenderTargets, DrawBuffers);
+    CHECK_GL_ERROR("Failed to set draw buffers via glDrawBuffers()");
+
+    GLenum Status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+    if (Status != GL_FRAMEBUFFER_COMPLETE)
+    {
+        const Char* StatusString = "Unknown";
+        switch (Status)
+        {
+            // clang-format off
+            case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT:         StatusString = "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT";         break;
+            case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT: StatusString = "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT"; break;
+            case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER:        StatusString = "GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER";        break;
+            case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER:        StatusString = "GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER";        break;
+            case GL_FRAMEBUFFER_UNSUPPORTED:                   StatusString = "GL_FRAMEBUFFER_UNSUPPORTED";                   break;
+            case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE:        StatusString = "GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE";        break;
+            case GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS:      StatusString = "GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS";      break;
+                // clang-format on
+        }
+        LOG_ERROR("Framebuffer is incomplete. FB status: ", StatusString);
+        UNEXPECTED("Framebuffer is incomplete");
+    }
+    return FBO;
+}
+
 const GLObjectWrappers::GLFrameBufferObj& FBOCache::GetFBO(Uint32             NumRenderTargets,
                                                            TextureViewGLImpl* ppRTVs[],
                                                            TextureViewGLImpl* pDSV,
@@ -163,108 +273,7 @@ const GLObjectWrappers::GLFrameBufferObj& FBOCache::GetFBO(Uint32             Nu
     else
     {
         // Create a new FBO
-        GLObjectWrappers::GLFrameBufferObj NewFBO(true);
-
-        ContextState.BindFBO(NewFBO);
-
-        // Initialize the FBO
-        for (Uint32 rt = 0; rt < NumRenderTargets; ++rt)
-        {
-            if (auto* pRTView = ppRTVs[rt])
-            {
-                const auto& RTVDesc     = pRTView->GetDesc();
-                auto*       pColorTexGL = pRTView->GetTexture<TextureBaseGL>();
-                pColorTexGL->AttachToFramebuffer(RTVDesc, GL_COLOR_ATTACHMENT0 + rt);
-            }
-        }
-
-        if (pDSV != nullptr)
-        {
-            const auto& DSVDesc         = pDSV->GetDesc();
-            auto*       pDepthTexGL     = pDSV->GetTexture<TextureBaseGL>();
-            GLenum      AttachmentPoint = 0;
-            if (DSVDesc.Format == TEX_FORMAT_D32_FLOAT ||
-                DSVDesc.Format == TEX_FORMAT_D16_UNORM)
-            {
-#ifdef DILIGENT_DEBUG
-                {
-                    const auto GLTexFmt = pDepthTexGL->GetGLTexFormat();
-                    VERIFY(GLTexFmt == GL_DEPTH_COMPONENT32F || GLTexFmt == GL_DEPTH_COMPONENT16,
-                           "Inappropriate internal texture format (", GLTexFmt,
-                           ") for depth attachment. GL_DEPTH_COMPONENT32F or GL_DEPTH_COMPONENT16 is expected");
-                }
-#endif
-                AttachmentPoint = GL_DEPTH_ATTACHMENT;
-            }
-            else if (DSVDesc.Format == TEX_FORMAT_D32_FLOAT_S8X24_UINT ||
-                     DSVDesc.Format == TEX_FORMAT_D24_UNORM_S8_UINT)
-            {
-#ifdef DILIGENT_DEBUG
-                {
-                    const auto GLTexFmt = pDepthTexGL->GetGLTexFormat();
-                    VERIFY(GLTexFmt == GL_DEPTH24_STENCIL8 || GLTexFmt == GL_DEPTH32F_STENCIL8,
-                           "Inappropriate internal texture format (", GLTexFmt,
-                           ") for depth-stencil attachment. GL_DEPTH24_STENCIL8 or GL_DEPTH32F_STENCIL8 is expected");
-                }
-#endif
-                AttachmentPoint = GL_DEPTH_STENCIL_ATTACHMENT;
-            }
-            else
-            {
-                UNEXPECTED(GetTextureFormatAttribs(DSVDesc.Format).Name, " is not valid depth-stencil view format");
-            }
-            pDepthTexGL->AttachToFramebuffer(DSVDesc, AttachmentPoint);
-        }
-
-        // We now need to set mapping between shader outputs and
-        // color attachments. This largely redundant step is performed
-        // by glDrawBuffers()
-        // clang-format off
-        static const GLenum DrawBuffers[] = 
-        { 
-            GL_COLOR_ATTACHMENT0, 
-            GL_COLOR_ATTACHMENT1, 
-            GL_COLOR_ATTACHMENT2, 
-            GL_COLOR_ATTACHMENT3,
-            GL_COLOR_ATTACHMENT4,
-            GL_COLOR_ATTACHMENT5,
-            GL_COLOR_ATTACHMENT6,
-            GL_COLOR_ATTACHMENT7,
-            GL_COLOR_ATTACHMENT8,
-            GL_COLOR_ATTACHMENT9,
-            GL_COLOR_ATTACHMENT10,
-            GL_COLOR_ATTACHMENT11,
-            GL_COLOR_ATTACHMENT12,
-            GL_COLOR_ATTACHMENT13,
-            GL_COLOR_ATTACHMENT14,
-            GL_COLOR_ATTACHMENT15
-        };
-        // clang-format on
-
-        // The state set by glDrawBuffers() is part of the state of the framebuffer.
-        // So it can be set up once and left it set.
-        glDrawBuffers(NumRenderTargets, DrawBuffers);
-        CHECK_GL_ERROR("Failed to set draw buffers via glDrawBuffers()");
-
-        GLenum Status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
-        if (Status != GL_FRAMEBUFFER_COMPLETE)
-        {
-            const Char* StatusString = "Unknown";
-            switch (Status)
-            {
-                // clang-format off
-                case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT:         StatusString = "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT";         break;
-                case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT: StatusString = "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT"; break;
-                case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER:        StatusString = "GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER";        break;
-                case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER:        StatusString = "GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER";        break;
-                case GL_FRAMEBUFFER_UNSUPPORTED:                   StatusString = "GL_FRAMEBUFFER_UNSUPPORTED";                   break;
-                case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE:        StatusString = "GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE";        break;
-                case GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS:      StatusString = "GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS";      break;
-                    // clang-format on
-            }
-            LOG_ERROR("Framebuffer is incomplete. FB status: ", StatusString);
-            UNEXPECTED("Framebuffer is incomplete");
-        }
+        auto NewFBO = CreateFBO(ContextState, NumRenderTargets, ppRTVs, pDSV);
 
         auto NewElems = m_Cache.emplace(std::make_pair(Key, std::move(NewFBO)));
         // New element must be actually inserted
diff --git a/Graphics/GraphicsEngineOpenGL/src/FramebufferGLImpl.cpp b/Graphics/GraphicsEngineOpenGL/src/FramebufferGLImpl.cpp
new file mode 100644
index 00000000..c84d9816
--- /dev/null
+++ b/Graphics/GraphicsEngineOpenGL/src/FramebufferGLImpl.cpp
@@ -0,0 +1,138 @@
+/*
+ *  Copyright 2019-2020 Diligent Graphics LLC
+ *  Copyright 2015-2019 Egor Yusov
+ *  
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *  
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  In no event and under no legal theory, whether in tort (including negligence), 
+ *  contract, or otherwise, unless required by applicable law (such as deliberate 
+ *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
+ *  liable for any damages, including any direct, indirect, special, incidental, 
+ *  or consequential damages of any character arising as a result of this License or 
+ *  out of the use or inability to use the software (including but not limited to damages 
+ *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
+ *  all other commercial damages or losses), even if such Contributor has been advised 
+ *  of the possibility of such damages.
+ */
+
+#include "pch.h"
+
+#include "FramebufferGLImpl.hpp"
+#include "FBOCache.hpp"
+#include "TextureViewGLImpl.hpp"
+
+namespace Diligent
+{
+
+static bool UseDefaultFBO(Uint32             NumRenderTargets,
+                          TextureViewGLImpl* ppRTVs[],
+                          TextureViewGLImpl* pDSV)
+{
+    bool useDefaultFBO = false;
+    for (Uint32 rt = 0; rt < NumRenderTargets; ++rt)
+    {
+        if (ppRTVs[rt] != nullptr && ppRTVs[rt]->GetHandle() == 0)
+        {
+            if (rt == 0)
+            {
+                useDefaultFBO = true;
+            }
+            else
+            {
+                LOG_ERROR_AND_THROW("In OpenGL, swap chain back buffer can be the only render target in the framebuffer "
+                                    "and cannot be combined with any other render target.");
+            }
+        }
+    }
+
+    if (pDSV != nullptr)
+    {
+        if (useDefaultFBO && pDSV->GetHandle() != 0)
+        {
+            LOG_ERROR_AND_THROW("In OpenGL, swap chain back buffer can only be paired with the default depth-stencil buffer.");
+        }
+
+        if (pDSV->GetHandle() == 0)
+        {
+            if (!useDefaultFBO && NumRenderTargets > 0)
+            {
+                LOG_ERROR_AND_THROW("In OpenGL, the swap chain's depth-stencil buffer can only be paired with its back buffer.");
+            }
+            else
+            {
+                useDefaultFBO = true;
+            }
+        }
+    }
+
+    return useDefaultFBO;
+}
+
+FramebufferGLImpl::FramebufferGLImpl(IReferenceCounters*    pRefCounters,
+                                     RenderDeviceGLImpl*    pDevice,
+                                     GLContextState&        CtxState,
+                                     const FramebufferDesc& Desc) :
+    TFramebufferBase{pRefCounters, pDevice, Desc}
+{
+    const auto& RPDesc = m_Desc.pRenderPass->GetDesc();
+    m_SubpassFramebuffers.reserve(RPDesc.SubpassCount);
+    for (Uint32 subpass = 0; subpass < RPDesc.SubpassCount; ++subpass)
+    {
+        const auto& SubpassDesc = RPDesc.pSubpasses[subpass];
+
+        TextureViewGLImpl* ppRTVs[MAX_RENDER_TARGETS] = {};
+        TextureViewGLImpl* pDSV                       = nullptr;
+
+        for (Uint32 rt = 0; rt < SubpassDesc.RenderTargetAttachmentCount; ++rt)
+        {
+            const auto& RTAttachmentRef = SubpassDesc.pRenderTargetAttachments[rt];
+            if (RTAttachmentRef.AttachmentIndex != ATTACHMENT_UNUSED)
+            {
+                ppRTVs[rt] = ValidatedCast<TextureViewGLImpl>(m_Desc.ppAttachments[RTAttachmentRef.AttachmentIndex]);
+            }
+        }
+
+        if (SubpassDesc.pDepthStencilAttachment != nullptr && SubpassDesc.pDepthStencilAttachment->AttachmentIndex != ATTACHMENT_UNUSED)
+        {
+            pDSV = ValidatedCast<TextureViewGLImpl>(m_Desc.ppAttachments[SubpassDesc.pDepthStencilAttachment->AttachmentIndex]);
+        }
+        auto RenderTargetFBO = UseDefaultFBO(SubpassDesc.RenderTargetAttachmentCount, ppRTVs, pDSV) ?
+            GLObjectWrappers::GLFrameBufferObj{false} :
+            FBOCache::CreateFBO(CtxState, SubpassDesc.RenderTargetAttachmentCount, ppRTVs, pDSV);
+
+        GLObjectWrappers::GLFrameBufferObj ResolveFBO{false};
+        if (SubpassDesc.pResolveAttachments != nullptr)
+        {
+            TextureViewGLImpl* ppRsvlViews[MAX_RENDER_TARGETS] = {};
+            for (Uint32 rt = 0; rt < SubpassDesc.RenderTargetAttachmentCount; ++rt)
+            {
+                const auto& RslvAttachmentRef = SubpassDesc.pResolveAttachments[rt];
+                if (RslvAttachmentRef.AttachmentIndex != ATTACHMENT_UNUSED)
+                {
+                    ppRsvlViews[rt] = ValidatedCast<TextureViewGLImpl>(m_Desc.ppAttachments[RslvAttachmentRef.AttachmentIndex]);
+                }
+            }
+            ResolveFBO = UseDefaultFBO(SubpassDesc.RenderTargetAttachmentCount, ppRsvlViews, nullptr) ?
+                GLObjectWrappers::GLFrameBufferObj{false} :
+                FBOCache::CreateFBO(CtxState, SubpassDesc.RenderTargetAttachmentCount, ppRsvlViews, nullptr);
+        }
+
+        m_SubpassFramebuffers.emplace_back(std::move(RenderTargetFBO), std::move(ResolveFBO));
+    }
+}
+
+FramebufferGLImpl::~FramebufferGLImpl()
+{
+}
+
+} // namespace Diligent
diff --git a/Graphics/GraphicsEngineOpenGL/src/RenderDeviceGLImpl.cpp b/Graphics/GraphicsEngineOpenGL/src/RenderDeviceGLImpl.cpp
index 5734ae75..ae77fbcf 100644
--- a/Graphics/GraphicsEngineOpenGL/src/RenderDeviceGLImpl.cpp
+++ b/Graphics/GraphicsEngineOpenGL/src/RenderDeviceGLImpl.cpp
@@ -46,6 +46,8 @@
 #include "ShaderResourceBindingGLImpl.hpp"
 #include "FenceGLImpl.hpp"
 #include "QueryGLImpl.hpp"
+#include "RenderPassGLImpl.hpp"
+#include "FramebufferGLImpl.hpp"
 #include "EngineMemory.h"
 #include "StringTools.hpp"
 
@@ -75,7 +77,9 @@ RenderDeviceGLImpl::RenderDeviceGLImpl(IReferenceCounters*       pRefCounters,
             sizeof(PipelineStateGLImpl),
             sizeof(ShaderResourceBindingGLImpl),
             sizeof(FenceGLImpl),
-            sizeof(QueryGLImpl)
+            sizeof(QueryGLImpl),
+            sizeof(RenderPassGLImpl),
+            sizeof(FramebufferGLImpl)
         }
     },
     // Device caps must be filled in before the constructor of Pipeline Cache is called!
@@ -515,6 +519,34 @@ void RenderDeviceGLImpl::CreateQuery(const QueryDesc& Desc, IQuery** ppQuery)
     );
 }
 
+void RenderDeviceGLImpl::CreateRenderPass(const RenderPassDesc& Desc, IRenderPass** ppRenderPass)
+{
+    CreateDeviceObject(
+        "RenderPass", Desc, ppRenderPass,
+        [&]() //
+        {
+            RenderPassGLImpl* pRenderPassOGL(NEW_RC_OBJ(m_RenderPassAllocator, "RenderPassGLImpl instance", RenderPassGLImpl)(this, Desc));
+            pRenderPassOGL->QueryInterface(IID_RenderPass, reinterpret_cast<IObject**>(ppRenderPass));
+            OnCreateDeviceObject(pRenderPassOGL);
+        } //
+    );
+}
+
+void RenderDeviceGLImpl::CreateFramebuffer(const FramebufferDesc& Desc, IFramebuffer** ppFramebuffer)
+{
+    CreateDeviceObject("Framebuffer", Desc, ppFramebuffer,
+                       [&]() //
+                       {
+                           auto spDeviceContext = GetImmediateContext();
+                           VERIFY(spDeviceContext, "Immediate device context has been destroyed");
+                           auto& GLState = spDeviceContext.RawPtr<DeviceContextGLImpl>()->GetContextState();
+
+                           FramebufferGLImpl* pFramebufferGL(NEW_RC_OBJ(m_FramebufferAllocator, "FramebufferGLImpl instance", FramebufferGLImpl)(this, GLState, Desc));
+                           pFramebufferGL->QueryInterface(IID_Framebuffer, reinterpret_cast<IObject**>(ppFramebuffer));
+                           OnCreateDeviceObject(pFramebufferGL);
+                       });
+}
+
 bool RenderDeviceGLImpl::CheckExtension(const Char* ExtensionString)
 {
     return m_ExtensionStrings.find(ExtensionString) != m_ExtensionStrings.end();
diff --git a/Graphics/GraphicsEngineOpenGL/src/RenderPassGLImpl.cpp b/Graphics/GraphicsEngineOpenGL/src/RenderPassGLImpl.cpp
new file mode 100644
index 00000000..2a9d0609
--- /dev/null
+++ b/Graphics/GraphicsEngineOpenGL/src/RenderPassGLImpl.cpp
@@ -0,0 +1,47 @@
+/*
+ *  Copyright 2019-2020 Diligent Graphics LLC
+ *  Copyright 2015-2019 Egor Yusov
+ *  
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *  
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  In no event and under no legal theory, whether in tort (including negligence), 
+ *  contract, or otherwise, unless required by applicable law (such as deliberate 
+ *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
+ *  liable for any damages, including any direct, indirect, special, incidental, 
+ *  or consequential damages of any character arising as a result of this License or 
+ *  out of the use or inability to use the software (including but not limited to damages 
+ *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
+ *  all other commercial damages or losses), even if such Contributor has been advised 
+ *  of the possibility of such damages.
+ */
+
+#include "pch.h"
+
+#include "RenderPassGLImpl.hpp"
+#include "EngineMemory.h"
+
+namespace Diligent
+{
+
+RenderPassGLImpl::RenderPassGLImpl(IReferenceCounters*   pRefCounters,
+                                   RenderDeviceGLImpl*   pDevice,
+                                   const RenderPassDesc& Desc) :
+    TRenderPassBase{pRefCounters, pDevice, Desc}
+{
+}
+
+RenderPassGLImpl::~RenderPassGLImpl()
+{
+}
+
+} // namespace Diligent
diff --git a/Graphics/GraphicsEngineOpenGL/src/TextureBaseGL.cpp b/Graphics/GraphicsEngineOpenGL/src/TextureBaseGL.cpp
index 06e49cd6..86b5ef40 100644
--- a/Graphics/GraphicsEngineOpenGL/src/TextureBaseGL.cpp
+++ b/Graphics/GraphicsEngineOpenGL/src/TextureBaseGL.cpp
@@ -579,7 +579,10 @@ void TextureBaseGL::CopyData(DeviceContextGLImpl* pDeviceCtxGL,
     }
 
 #if GL_ARB_copy_image
-    if (glCopyImageSubData)
+    const bool IsDefaultBackBuffer = GetGLHandle() == 0;
+    // We can't use glCopyImageSubData with the proxy texture of a default framebuffer
+    // because we don't have the texture handle. Resort to quad rendering in this case.
+    if (glCopyImageSubData && !IsDefaultBackBuffer)
     {
         GLint SrcSliceY = (SrcTexDesc.Type == RESOURCE_DIM_TEX_1D_ARRAY) ? SrcSlice : 0;
         GLint SrcSliceZ = (SrcTexDesc.Type == RESOURCE_DIM_TEX_2D_ARRAY) ? SrcSlice : 0;