Enable VK_KHR_portability_subset if available

Makes it easy to use vulkan on macOS since vk-bootstrap will auto-enable it if
the extension is available.

This can be disabled by calling `disable_portability_subset`.

src/VkBootstrap.cpp

@@ -1182,11 +1182,20 @@ detail::Result<std::vector<PhysicalDevice>> PhysicalDeviceSelector::select_impl(
 	auto fill_out_phys_dev_with_criteria = [&](PhysicalDevice& phys_dev) {
 		phys_dev.features = criteria.required_features;
 		phys_dev.extended_features_chain = criteria.extended_features_chain;
+		bool portability_ext_available = false;
+		for (const auto& ext : phys_dev.extensions)
+			if (criteria.enable_portability_subset && ext == "VK_KHR_portability_subset")
+				portability_ext_available = true;
+
+		phys_dev.extensions.clear();
 		phys_dev.extensions.insert(
 		    phys_dev.extensions.end(), criteria.required_extensions.begin(), criteria.required_extensions.end());
 		auto desired_extensions_supported = detail::check_device_extension_support(phys_dev.extensions, criteria.desired_extensions);
 		phys_dev.extensions.insert(
 		    phys_dev.extensions.end(), desired_extensions_supported.begin(), desired_extensions_supported.end());
+		if (portability_ext_available) {
+			phys_dev.extensions.push_back("VK_KHR_portability_subset");
+		}
 	};
 
 	// if this option is set, always return only the first physical device found
@@ -1216,6 +1225,11 @@ detail::Result<std::vector<PhysicalDevice>> PhysicalDeviceSelector::select_impl(
 		physical_devices.erase(partition_index, physical_devices.end() - 1);
 	}
 
+	// Make the physical device ready to be used to create a Device from it
+	for (auto& physical_device : physical_devices) {
+		fill_out_phys_dev_with_criteria(physical_device);
+	}
+
 	return physical_devices;
 }
 
@@ -1324,6 +1338,11 @@ PhysicalDeviceSelector& PhysicalDeviceSelector::set_desired_version(uint32_t maj
 	criteria.desired_version = VKB_MAKE_VK_VERSION(0, major, minor, 0);
 	return *this;
 }
+PhysicalDeviceSelector& PhysicalDeviceSelector::disable_portability_subset() {
+	criteria.enable_portability_subset = false;
+	return *this;
+}
+
 PhysicalDeviceSelector& PhysicalDeviceSelector::set_required_features(VkPhysicalDeviceFeatures const& features) {
 	criteria.required_features = features;
 	return *this;

src/VkBootstrap.h

@@ -580,6 +580,10 @@ class PhysicalDeviceSelector {
 	// Require a physical device that supports a (major, minor) version of vulkan.
 	PhysicalDeviceSelector& set_minimum_version(uint32_t major, uint32_t minor);
 
+	// By default PhysicalDeviceSelector enables the portability subset if available
+	// This function disables that behavior
+	PhysicalDeviceSelector& disable_portability_subset();
+
 	// Require a physical device which supports a specific set of general/extension features.
 #if defined(VKB_VK_API_VERSION_1_1)
 	template <typename T> PhysicalDeviceSelector& add_required_extension_features(T const& features) {
@@ -648,6 +652,7 @@ class PhysicalDeviceSelector {
 #endif
 		bool defer_surface_initialization = false;
 		bool use_first_gpu_unconditionally = false;
+		bool enable_portability_subset = true;
 	} criteria;
 
 	PhysicalDevice populate_device_details(VkPhysicalDevice phys_device,