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, 9 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoanativeinterface.mm b/src/plugins/platforms/cocoa/qcocoanativeinterface.mm
index b4af4a6e01..2a6c25ed75 100644
--- a/src/plugins/platforms/cocoa/qcocoanativeinterface.mm
+++ b/src/plugins/platforms/cocoa/qcocoanativeinterface.mm
@@ -71,6 +71,10 @@
 
 #include <AppKit/AppKit.h>
 
+#if QT_CONFIG(vulkan)
+#include <MoltenVK/mvk_vulkan.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 QCocoaNativeInterface::QCocoaNativeInterface()
@@ -104,6 +108,11 @@ void *QCocoaNativeInterface::nativeResourceForWindow(const QByteArray &resourceS
 #endif
     } else if (resourceString == "nswindow") {
         return static_cast<QCocoaWindow *>(window->handle())->nativeWindow();
+#if QT_CONFIG(vulkan)
+    } else if (resourceString == "vkSurface") {
+        if (QVulkanInstance *instance = window->vulkanInstance())
+            return static_cast<QCocoaVulkanInstance *>(instance->handle())->createSurface(window);
+#endif
     }
     return nullptr;
 }