04_logical_device.rs.diff

--- a/03_physical_device_selection.rs
+++ b/04_logical_device.rs
@@ -15,6 +15,7 @@ use vulkano::instance::{
     PhysicalDevice,
 };
 use vulkano::instance::debug::{DebugCallback, MessageTypes};
+use vulkano::device::{Device, DeviceExtensions, Queue, Features};
 
 const WIDTH: u32 = 800;
 const HEIGHT: u32 = 600;
@@ -49,6 +50,9 @@ struct HelloTriangleApplication {
     events_loop: EventsLoop,
 
     physical_device_index: usize, // can't store PhysicalDevice directly (lifetime issues)
+    device: Arc<Device>,
+
+    graphics_queue: Arc<Queue>,
 }
 
 impl HelloTriangleApplication {
@@ -59,6 +63,8 @@ impl HelloTriangleApplication {
         let events_loop = Self::init_window();
 
         let physical_device_index = Self::pick_physical_device(&instance);
+        let (device, graphics_queue) = Self::create_logical_device(
+            &instance, physical_device_index);
 
         Self {
             instance,
@@ -67,6 +73,9 @@ impl HelloTriangleApplication {
             events_loop,
 
             physical_device_index,
+            device,
+
+            graphics_queue,
         }
     }
 
@@ -166,6 +175,31 @@ impl HelloTriangleApplication {
         indices
     }
 
+    fn create_logical_device(
+        instance: &Arc<Instance>,
+        physical_device_index: usize,
+    ) -> (Arc<Device>, Arc<Queue>) {
+        let physical_device = PhysicalDevice::from_index(&instance, physical_device_index).unwrap();
+        let indices = Self::find_queue_families(&physical_device);
+
+        let queue_family = physical_device.queue_families()
+            .nth(indices.graphics_family as usize).unwrap();
+
+        let queue_priority = 1.0;
+
+        // NOTE: the tutorial recommends passing the validation layers as well
+        // for legacy reasons (if ENABLE_VALIDATION_LAYERS is true). Vulkano handles that
+        // for us internally.
+
+        let (device, mut queues) = Device::new(physical_device, &Features::none(), &DeviceExtensions::none(),
+            [(queue_family, queue_priority)].iter().cloned())
+            .expect("failed to create logical device!");
+
+        let graphics_queue = queues.next().unwrap();
+
+        (device, graphics_queue)
+    }
+
     #[allow(unused)]
     fn main_loop(&mut self) {
         loop {