Update app to allow tearing by default if supported

DeviceResources.cpp

@@ -55,6 +55,7 @@ DX::DeviceResources::DeviceResources(DXGI_FORMAT       backBufferFormat,
     , m_dpi(-1.0f)
     ,  // Require DPI to be explicitly set.
     m_vTotalMode(false)
+    , m_tearingSupport(false)
 {
     UNREFERENCED_PARAMETER(minFeatureLevel);
 
@@ -233,9 +234,7 @@ void DX::DeviceResources::CreateWindowSizeDependentResources()
         }
         else
         {
-            swapFlags = 0;                  // default is vsync on, not tearing
-//          swapFlags = DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;  // It is recommended to always use the tearing flag when it is available.
-//          swapChainDesc.Flags = m_tearingSupport ? DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING : 0;  TODO make this not hard-coded -then older systems may work
+            swapFlags = m_tearingSupport ? DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING : 0;
         }
         // If the swap chain already exists, resize it.
         HRESULT hr = m_swapChain->ResizeBuffers(m_backBufferCount, backBufferWidth, backBufferHeight, m_backBufferFormat, swapFlags);
@@ -294,9 +293,7 @@ void DX::DeviceResources::CreateWindowSizeDependentResources()
         }
         else
         {
-            swapFlags = 0;                  // default is vsync enabled, not tearing
-//          swapFlags = DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;  // It is recommended to always use the tearing flag when it is available.
-//          swapChainDesc.Flags = m_tearingSupport ? DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING : 0;  TODO make this not hard-coded -then older systems may work
+            swapFlags = m_tearingSupport ? DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING : 0;
         }
         swapChainDesc.Flags = swapFlags;
 
@@ -465,8 +462,13 @@ HRESULT DX::DeviceResources::Present(UINT syncInterval, UINT flags)
     // flag when it is supported, even when presenting in windowed mode.
     // However, this flag cannot be used if the app is in fullscreen mode as a
     // result of calling SetFullscreenState.
-    //  UINT presentFlags = (m_tearingSupport && m_windowedMode) ? DXGI_PRESENT_ALLOW_TEARING : 0;
-    HRESULT hr = m_swapChain->Present(syncInterval, flags);
+    UINT presentFlags = flags;
+    if (m_tearingSupport && syncInterval == 0)
+    {
+        presentFlags |= DXGI_PRESENT_ALLOW_TEARING;
+    }
+
+    HRESULT hr = m_swapChain->Present(syncInterval, presentFlags);
 
     if (m_d3dContext)
     {

DeviceResources.h

@@ -50,6 +50,10 @@ namespace DX
         {
             m_vTotalMode = vTotalMode;
         }  // Tell DevResources object when we are requesting v-total Fixed.
+        void SetTearingSupport(bool tearingSupport)
+        {
+            m_tearingSupport = tearingSupport;
+        }
 
         // The size of the render target, in pixels.
         RECT GetOutputSize() const
@@ -185,6 +189,7 @@ namespace DX
         Microsoft::WRL::ComPtr<ID3DUserDefinedAnnotation> m_d3dAnnotation;
         HANDLE                                            m_frameLatencyHandle;
         BOOL                                              m_vTotalMode;  // True for a FIXED v-total average swapchain
+        bool                                              m_tearingSupport;
 
         // Direct3D rendering objects. Required for 3D.
         Microsoft::WRL::ComPtr<ID3D11Texture2D>        m_renderTarget;

Game.cpp

@@ -214,6 +214,9 @@ void Game::RotateFrameLog()
 // Initialize the Direct3D resources required to run.
 void Game::Initialize(HWND window, int width, int height)
 {
+	CheckTearingSupport();
+	m_deviceResources->SetTearingSupport(m_tearingSupport);
+
 	m_deviceResources->SetWindow(window, width, height);
 	m_deviceResources->CreateDeviceResources();
 	m_deviceResources->SetDpi(96.0f);  // TODO: using default 96 DPI for now