macOS: Experimental Vulkan support via MoltenVK

Add support for QSurface::VulkanSurface and QVulkanWindow.

Usage:
  1) Build MoltenVK according to instructions
  2) Configure Qt: ./configure -I /path/to/MoltenVK/Package/Release/MoltenVK/include
  3) export QT_VULKAN_LIB=/path/to/MoltenVK/Package/Release/MoltenVK/macOS/libMoltenVK.

Implement support for QSurface::VulkanSurface by enabling
layer mode for QNSView and then creating a CAMetalLayer,
which the MoltenVK translation layer can run on.

MoltenVK provides an implementation of the Vulcan API,
which means that the platform integration is similar
to other platforms: implement a QCocoaVulkanInstance
where we pass the QNSView instance to the vkCreateMacOSSurfaceMVK
Vulkan surface constructor function.

Using Vulkan directly without QVulkanWindow is possible, but not
tested.

We currently load libMoltenVK at run-time and use the
existing QT_VULKAN_LIB environment variable to set its
path. For deployment purposes it would be better to
link against MoltenVK.frameworkm, but this

Task-number: QTBUG-66966
Change-Id: I04ec6289c40b199dca9fed32902b5d2ad4e9c030
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.h b/src/plugins/platforms/cocoa/qcocoawindow.h
index feaade1bd6..225c7eda84 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.h
+++ b/src/plugins/platforms/cocoa/qcocoawindow.h
@@ -53,6 +53,10 @@
 #include "qnswindow.h"
 #include "qt_mac_p.h"
 
+#if QT_CONFIG(vulkan)
+#include <MoltenVK/mvk_vulkan.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 #ifndef QT_NO_DEBUG_STREAM
@@ -281,6 +285,10 @@ public: // for QNSView
     };
     QHash<quintptr, BorderRange> m_contentBorderAreas; // identifer -> uppper/lower
     QHash<quintptr, bool> m_enabledContentBorderAreas; // identifer -> enabled state (true/false)
+
+#if QT_CONFIG(vulkan)
+    VkSurfaceKHR m_vulkanSurface = nullptr;
+#endif
 };
 
 #ifndef QT_NO_DEBUG_STREAM