02_validation_layers.rs.diff

--- a/01_instance_creation.rs
+++ b/02_validation_layers.rs
@@ -11,24 +11,41 @@ use vulkano::instance::{
     InstanceExtensions,
     ApplicationInfo,
     Version,
+    layers_list,
 };
+use vulkano::instance::debug::{DebugCallback, MessageTypes};
 
 const WIDTH: u32 = 800;
 const HEIGHT: u32 = 600;
 
+const VALIDATION_LAYERS: &[&str] =  &[
+    "VK_LAYER_LUNARG_standard_validation"
+];
+
+#[cfg(all(debug_assertions))]
+const ENABLE_VALIDATION_LAYERS: bool = true;
+#[cfg(not(debug_assertions))]
+const ENABLE_VALIDATION_LAYERS: bool = false;
+
 #[allow(unused)]
 struct HelloTriangleApplication {
     instance: Arc<Instance>,
+    debug_callback: Option<DebugCallback>,
+
     events_loop: EventsLoop,
 }
 
 impl HelloTriangleApplication {
     pub fn initialize() -> Self {
         let instance = Self::create_instance();
+        let debug_callback = Self::setup_debug_callback(&instance);
+
         let events_loop = Self::init_window();
 
         Self {
             instance,
+            debug_callback,
+
             events_loop,
         }
     }
@@ -43,6 +60,10 @@ impl HelloTriangleApplication {
     }
 
     fn create_instance() -> Arc<Instance> {
+        if ENABLE_VALIDATION_LAYERS && !Self::check_validation_layer_support() {
+            println!("Validation layers requested, but not available!")
+        }
+
         let supported_extensions = InstanceExtensions::supported_by_core()
             .expect("failed to retrieve supported extensions");
         println!("Supported extensions: {:?}", supported_extensions);
@@ -54,9 +75,48 @@ impl HelloTriangleApplication {
             engine_version: Some(Version { major: 1, minor: 0, patch: 0 }),
         };
 
-        let required_extensions = vulkano_win::required_extensions();
-        Instance::new(Some(&app_info), &required_extensions, None)
-            .expect("failed to create Vulkan instance")
+        let required_extensions = Self::get_required_extensions();
+
+        if ENABLE_VALIDATION_LAYERS && Self::check_validation_layer_support() {
+            Instance::new(Some(&app_info), &required_extensions, VALIDATION_LAYERS.iter().cloned())
+                .expect("failed to create Vulkan instance")
+        } else {
+            Instance::new(Some(&app_info), &required_extensions, None)
+                .expect("failed to create Vulkan instance")
+        }
+    }
+
+    fn check_validation_layer_support() -> bool {
+        let layers: Vec<_> = layers_list().unwrap().map(|l| l.name().to_owned()).collect();
+        VALIDATION_LAYERS.iter()
+            .all(|layer_name| layers.contains(&layer_name.to_string()))
+    }
+
+    fn get_required_extensions() -> InstanceExtensions {
+        let mut extensions = vulkano_win::required_extensions();
+        if ENABLE_VALIDATION_LAYERS {
+            // TODO!: this should be ext_debug_utils (_report is deprecated), but that doesn't exist yet in vulkano
+            extensions.ext_debug_report = true;
+        }
+
+        extensions
+    }
+
+    fn setup_debug_callback(instance: &Arc<Instance>) -> Option<DebugCallback> {
+        if !ENABLE_VALIDATION_LAYERS  {
+            return None;
+        }
+
+        let msg_types = MessageTypes {
+            error: true,
+            warning: true,
+            performance_warning: true,
+            information: false,
+            debug: true,
+        };
+        DebugCallback::new(&instance, msg_types, |msg| {
+            println!("validation layer: {:?}", msg.description);
+        }).ok()
     }
 
     #[allow(unused)]