libretro: disable layered rendering where not supported

I suspect this causes some pretty weird rendering issues on older
hardware but it's better than outright crashing. Need to look into how
to do this better.

src/citra_libretro/libretro_vk.cpp

@@ -217,17 +217,39 @@ void LibRetroVKInstance::DetectDeviceCapabilities() {
     // Query extended features if available
     vk::PhysicalDeviceFeatures2 features2;
     vk::PhysicalDeviceTimelineSemaphoreFeatures timeline_features;
+    vk::PhysicalDeviceVulkan12Features vulkan12_features;
+
+    // Chain the feature structures
+    void* pNext = nullptr;
+
+    // Check for layered rendering support on MoltenVK (maps to shaderOutputLayer)
+    if (driver_id == vk::DriverIdKHR::eMoltenvk) {
+        vulkan12_features.pNext = pNext;
+        pNext = &vulkan12_features;
+    }
 
     if (timeline_semaphores) {
-        features2.pNext = &timeline_features;
-        timeline_features.pNext = nullptr;
+        timeline_features.pNext = pNext;
+        pNext = &timeline_features;
     }
 
+    features2.pNext = pNext;
+
     try {
         physical_device.getFeatures2(&features2);
         if (timeline_semaphores) {
             timeline_semaphores = timeline_features.timelineSemaphore;
         }
+
+        // Check layered rendering support on MoltenVK
+        // MoltenVK maps _metalFeatures.layeredRendering to _vulkan12FeaturesNoExt.shaderOutputLayer
+        if (driver_id == vk::DriverIdKHR::eMoltenvk) {
+            if (!vulkan12_features.shaderOutputLayer) {
+                LOG_INFO(Render_Vulkan,
+                         "Disabling layered rendering (shaderOutputLayer not supported by device)");
+                layered_rendering_supported = false;
+            }
+        }
     } catch (const vk::SystemError& e) {
         LOG_WARNING(Render_Vulkan, "Failed to query extended features: {}", e.what());
     }

src/video_core/renderer_vulkan/vk_instance.h

@@ -250,6 +250,11 @@ public:
         return features.shaderSampledImageArrayDynamicIndexing;
     }
 
+    /// Returns true if layered rendering (array attachments) is supported
+    bool IsLayeredRenderingSupported() const {
+        return layered_rendering_supported;
+    }
+
     /// Returns the minimum vertex stride alignment
     u32 GetMinVertexStrideAlignment() const {
         return min_vertex_stride_alignment;
@@ -324,6 +329,7 @@ protected:
     bool shader_stencil_export{};
     bool external_memory_host{};
     u64 min_imported_host_pointer_alignment{};
+    bool layered_rendering_supported{true};
     bool tooling_info{};
     bool debug_utils_supported{};
     bool has_nsight_graphics{};

src/video_core/renderer_vulkan/vk_texture_runtime.cpp

@@ -146,7 +146,10 @@ Handle MakeHandle(const Instance* instance, u32 width, u32 height, u32 levels, T
                   vk::Format format, vk::ImageUsageFlags usage, vk::ImageCreateFlags flags,
                   vk::ImageAspectFlags aspect, bool need_format_list,
                   std::string_view debug_name = {}) {
-    const u32 layers = type == TextureType::CubeMap ? 6 : 1;
+    // On tvOS/iOS, fall back to 2D textures when layered rendering isn't supported
+    const bool is_cube_map =
+        type == TextureType::CubeMap && instance->IsLayeredRenderingSupported();
+    const u32 layers = is_cube_map ? 6 : 1;
 
     const std::array format_list = {
         vk::Format::eR8G8B8A8Unorm,
@@ -192,8 +195,7 @@ Handle MakeHandle(const Instance* instance, u32 width, u32 height, u32 levels, T
     const vk::Image image{unsafe_image};
     const vk::ImageViewCreateInfo view_info = {
         .image = image,
-        .viewType =
-            type == TextureType::CubeMap ? vk::ImageViewType::eCube : vk::ImageViewType::e2D,
+        .viewType = is_cube_map ? vk::ImageViewType::eCube : vk::ImageViewType::e2D,
         .format = format,
         .subresourceRange{
             .aspectMask = aspect,