From 97b32f52cc123544a1352527c2509c804fd3d190 Mon Sep 17 00:00:00 2001
From: Egor Yusov <egor.yusov@gmail.com>
Date: Mon, 12 Aug 2019 22:00:42 -0700
Subject: D3D12 backend: enabled multiple swap chain support

---
 Graphics/GraphicsEngine/include/SwapChainBase.h | 50 +++++++++++++++++++++++--
 Graphics/GraphicsEngine/interface/SwapChain.h   |  3 ++
 2 files changed, 50 insertions(+), 3 deletions(-)

(limited to 'Graphics/GraphicsEngine')

diff --git a/Graphics/GraphicsEngine/include/SwapChainBase.h b/Graphics/GraphicsEngine/include/SwapChainBase.h
index 8b9aa86f..5a60c9ed 100644
--- a/Graphics/GraphicsEngine/include/SwapChainBase.h
+++ b/Graphics/GraphicsEngine/include/SwapChainBase.h
@@ -26,6 +26,8 @@
 /// \file
 /// Implementation of the Diligent::SwapChainBase template class
 
+#include <array>
+
 #include "RenderDevice.h"
 #include "DeviceContext.h"
 #include "SwapChain.h"
@@ -89,13 +91,55 @@ protected:
 
         return false;
     }
-    
+
+    template<typename DeviceContextImplType>
+    bool UnbindRenderTargets(DeviceContextImplType* pImmediateCtx,
+                             ITextureView*          ppBackBufferRTVs[],
+                             Uint32                 NumBackBufferRTVs,
+                             ITextureView*          pDSV)
+    {
+        bool RebindRenderTargets = false; 
+        bool UnbindRenderTargets = false;
+        if (m_SwapChainDesc.IsPrimary)
+        {
+            RebindRenderTargets = UnbindRenderTargets = pImmediateCtx->IsDefaultFBBound();
+        }
+        else
+        {
+            std::array<ITextureView*, MaxRenderTargets> pBoundRTVs = {};
+            RefCntAutoPtr<ITextureView> pBoundDSV;
+            Uint32 NumRenderTargets = 0;
+            pImmediateCtx->GetRenderTargets(NumRenderTargets, pBoundRTVs.data(), &pBoundDSV);
+            for (Uint32 i=0; i < NumRenderTargets; ++i)
+            {
+                for (Uint32 j=0; j < NumBackBufferRTVs; ++j)
+                {
+                    if (pBoundRTVs[i] == ppBackBufferRTVs[j])
+                        UnbindRenderTargets = true;
+                }
+            }
+            if (pBoundDSV == pDSV)
+                UnbindRenderTargets = true;
+
+            for (auto pRTV : pBoundRTVs)
+            {
+                if (pRTV != nullptr)
+                    pRTV->Release();
+            }
+        }
+
+        if (UnbindRenderTargets)
+            pImmediateCtx->ResetRenderTargets();
+
+        return RebindRenderTargets;
+    }
+
     /// Strong reference to the render device
-    Diligent::RefCntAutoPtr<IRenderDevice> m_pRenderDevice;
+    RefCntAutoPtr<IRenderDevice> m_pRenderDevice;
     
     /// Weak references to the immediate device context. The context holds
     /// the strong reference to the swap chain.
-    Diligent::RefCntWeakPtr<IDeviceContext> m_wpDeviceContext;
+    RefCntWeakPtr<IDeviceContext> m_wpDeviceContext;
 
     /// Swap chain description
     SwapChainDesc m_SwapChainDesc;
diff --git a/Graphics/GraphicsEngine/interface/SwapChain.h b/Graphics/GraphicsEngine/interface/SwapChain.h
index 5e780292..164608e1 100644
--- a/Graphics/GraphicsEngine/interface/SwapChain.h
+++ b/Graphics/GraphicsEngine/interface/SwapChain.h
@@ -54,6 +54,9 @@ public:
 
     /// \param [in] NewWidth - New swap chain width, in pixels
     /// \param [in] NewHeight - New swap chain height, in pixels
+    /// 
+    /// \note When resizing non-primary swap chains, the engine unbinds the 
+    ///       swap chain buffers from the output.
     virtual void Resize( Uint32 NewWidth, Uint32 NewHeight ) = 0;
 
     /// Sets fullscreen mode (only supported on Win32 platform)
-- 
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