[d3d11] Add option to enforce mailbox present mode

dxvk.conf

@@ -69,6 +69,16 @@
 # d3d9.presentInterval = -1
 
 
+# Enables the mailbox present mode in case regular Vsync is disabled.
+# This should avoid tearing, but may be unsupported on some systems
+# or require setting dxgi.numBackBuffers to a higher value in order
+# to work properly. Please do not report issues with this option.
+#
+# Supported values: True, False
+
+# dxgi.tearFree = False
+
+
 # Performs range check on dynamically indexed constant buffers in shaders.
 # This may be needed to work around a certain type of game bug, but may
 # also introduce incorrect behaviour.

src/d3d11/d3d11_options.cpp

@@ -19,6 +19,7 @@ namespace dxvk {
     this->numBackBuffers        = config.getOption<int32_t>("dxgi.numBackBuffers", 0);
     this->maxFrameLatency       = config.getOption<int32_t>("dxgi.maxFrameLatency", 0);
     this->syncInterval          = config.getOption<int32_t>("dxgi.syncInterval", -1);
+    this->tearFree              = config.getOption<bool>("dxgi.tearFree", false);
 
     this->constantBufferRangeCheck = config.getOption<bool>("d3d11.constantBufferRangeCheck", false)
       && DxvkGpuVendor(devInfo.core.properties.vendorID) != DxvkGpuVendor::Amd;

src/d3d11/d3d11_options.h

@@ -72,6 +72,9 @@ namespace dxvk {
     /// passed to IDXGISwapChain::Present.
     int32_t syncInterval;
 
+    /// Tear-free mode if vsync is disabled
+    bool tearFree;
+
     /// Override maximum frame latency if the app specifies
     /// a higher value. May help with frame timing issues.
     int32_t maxFrameLatency;

src/d3d11/d3d11_swapchain.cpp

@@ -850,7 +850,8 @@ namespace dxvk {
     if (Vsync) {
       pDstModes[n++] = VK_PRESENT_MODE_FIFO_KHR;
     } else {
-      pDstModes[n++] = VK_PRESENT_MODE_IMMEDIATE_KHR;
+      if (!m_parent->GetOptions()->tearFree)
+        pDstModes[n++] = VK_PRESENT_MODE_IMMEDIATE_KHR;
       pDstModes[n++] = VK_PRESENT_MODE_MAILBOX_KHR;
       pDstModes[n++] = VK_PRESENT_MODE_FIFO_RELAXED_KHR;
     }