Implemented render pass MS resolve in OpenGL

4 files changed, 74 insertions, 6 deletions

diff --git a/Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp b/Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp
index 11886c11..aac30d49 100644
--- a/Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp
+++ b/Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp
@@ -267,6 +267,7 @@ private:
     __forceinline void PostDraw();
 
     void BeginSubpass();
+    void EndSubpass();
 
     Uint32 m_CommitedResourcesTentativeBarriers = 0;
 
diff --git a/Graphics/GraphicsEngineOpenGL/include/FramebufferGLImpl.hpp b/Graphics/GraphicsEngineOpenGL/include/FramebufferGLImpl.hpp
index 92d05e46..49ea8b84 100644
--- a/Graphics/GraphicsEngineOpenGL/include/FramebufferGLImpl.hpp
+++ b/Graphics/GraphicsEngineOpenGL/include/FramebufferGLImpl.hpp
@@ -54,13 +54,25 @@ public:
                       const FramebufferDesc& Desc);
     ~FramebufferGLImpl();
 
-    const GLObjectWrappers::GLFrameBufferObj& GetSubpassFramebuffer(Uint32 subpass)
+    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<GLObjectWrappers::GLFrameBufferObj> m_SubpassFramebuffers;
+    std::vector<SubpassFramebuffers> m_SubpassFramebuffers;
 };
 
 } // namespace Diligent
diff --git a/Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp b/Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp
index 265f9f0f..37e4a3f4 100644
--- a/Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp
+++ b/Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp
@@ -453,6 +453,39 @@ void DeviceContextGLImpl::BeginSubpass()
     }
 }
 
+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_DRAW_FRAMEBUFFER, SubpassFBOs.RenderTarget);
+        DEV_CHECK_GL_ERROR("Failed to bind subpass render target FBO as draw 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 texture");
+    }
+    m_ContextState.InvalidateFBO();
+}
+
 void DeviceContextGLImpl::BeginRenderPass(const BeginRenderPassAttribs& Attribs)
 {
     TDeviceContextBase::BeginRenderPass(Attribs);
@@ -462,7 +495,7 @@ void DeviceContextGLImpl::BeginRenderPass(const BeginRenderPassAttribs& Attribs)
         m_AttachmentClearValues[i] = Attribs.pClearValues[i];
 
     VERIFY_EXPR(m_pBoundFramebuffer);
-    m_ContextState.BindFBO(m_pBoundFramebuffer->GetSubpassFramebuffer(m_SubpassIndex));
+    m_ContextState.BindFBO(m_pBoundFramebuffer->GetSubpassFramebuffer(m_SubpassIndex).RenderTarget);
     SetViewports(1, nullptr, 0, 0);
 
     BeginSubpass();
@@ -470,16 +503,22 @@ void DeviceContextGLImpl::BeginRenderPass(const BeginRenderPassAttribs& Attribs)
 
 void DeviceContextGLImpl::NextSubpass()
 {
+    EndSubpass();
+
     TDeviceContextBase::NextSubpass();
 
-    m_ContextState.BindFBO(m_pBoundFramebuffer->GetSubpassFramebuffer(m_SubpassIndex));
+    m_ContextState.BindFBO(m_pBoundFramebuffer->GetSubpassFramebuffer(m_SubpassIndex).RenderTarget);
 
     BeginSubpass();
 }
 
 void DeviceContextGLImpl::EndRenderPass()
 {
+    EndSubpass();
+
     TDeviceContextBase::EndRenderPass();
+
+    m_ContextState.InvalidateFBO();
 }
 
 void DeviceContextGLImpl::BindProgramResources(Uint32& NewMemoryBarriers, IShaderResourceBinding* pResBinding)
diff --git a/Graphics/GraphicsEngineOpenGL/src/FramebufferGLImpl.cpp b/Graphics/GraphicsEngineOpenGL/src/FramebufferGLImpl.cpp
index d9f8341f..51abf1ba 100644
--- a/Graphics/GraphicsEngineOpenGL/src/FramebufferGLImpl.cpp
+++ b/Graphics/GraphicsEngineOpenGL/src/FramebufferGLImpl.cpp
@@ -62,8 +62,24 @@ FramebufferGLImpl::FramebufferGLImpl(IReferenceCounters*    pRefCounters,
         {
             pDSV = ValidatedCast<TextureViewGLImpl>(m_Desc.ppAttachments[SubpassDesc.pDepthStencilAttachment->AttachmentIndex]);
         }
-        auto FBO = FBOCache::CreateFBO(CtxState, SubpassDesc.RenderTargetAttachmentCount, ppRTVs, pDSV);
-        m_SubpassFramebuffers.emplace_back(std::move(FBO));
+        auto RenderTargetFBO = 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 = FBOCache::CreateFBO(CtxState, SubpassDesc.RenderTargetAttachmentCount, ppRsvlViews, nullptr);
+        }
+
+        m_SubpassFramebuffers.emplace_back(std::move(RenderTargetFBO), std::move(ResolveFBO));
     }
 }