Add more syncing to make sure we aren't wastefully rendering

src/app.rs

@@ -78,6 +78,12 @@ impl App {
     /// # Safety
     /// Here be Dragons
     pub unsafe fn render(&mut self, _window: &Window) -> Result<()> {
+        self.device.wait_for_fences(
+            &[self.data.in_flight_fences[self.frame]],
+            true,
+            u64::max_value(),
+        )?;
+
         let image_index = self
             .device
             .acquire_next_image_khr(
@@ -88,6 +94,16 @@ impl App {
             )?
             .0 as usize;
 
+        if !self.data.images_in_flight[image_index as usize].is_null() {
+            self.device.wait_for_fences(
+                &[self.data.images_in_flight[image_index as usize]],
+                true,
+                u64::max_value(),
+            )?;
+        }
+
+        self.data.images_in_flight[image_index as usize] = self.data.in_flight_fences[self.frame];
+
         let wait_semaphores = &[self.data.image_available_semaphores[self.frame]];
         let wait_stages = &[vk::PipelineStageFlags::COLOR_ATTACHMENT_OUTPUT];
         let command_buffers = &[self.data.command_buffers[image_index as usize]];
@@ -99,7 +115,13 @@ impl App {
             .signal_semaphores(signal_semaphores);
 
         self.device
-            .queue_submit(self.data.graphics_queue, &[submit_info], vk::Fence::null())?;
+            .reset_fences(&[self.data.in_flight_fences[self.frame]])?;
+
+        self.device.queue_submit(
+            self.data.graphics_queue,
+            &[submit_info],
+            self.data.in_flight_fences[self.frame],
+        )?;
 
         let swapchains = &[self.data.swapchain];
         let image_indices = &[image_index as u32];
@@ -121,6 +143,10 @@ impl App {
     /// # Safety
     /// Here be Dragons
     pub unsafe fn destroy(&mut self) {
+        self.data
+            .in_flight_fences
+            .iter()
+            .for_each(|f| self.device.destroy_fence(*f, None));
         self.data
             .render_finished_semaphores
             .iter()
@@ -186,6 +212,8 @@ pub struct AppData {
     // Sync Objects
     image_available_semaphores: Vec<vk::Semaphore>,
     render_finished_semaphores: Vec<vk::Semaphore>,
+    in_flight_fences: Vec<vk::Fence>,
+    images_in_flight: Vec<vk::Fence>,
 }
 
 impl AppData {}

src/app/functions.rs

@@ -629,13 +629,23 @@ pub(super) unsafe fn create_command_buffers(device: &Device, data: &mut AppData)
 
 pub(super) unsafe fn create_sync_objects(device: &Device, data: &mut AppData) -> Result<()> {
     let semaphore_info = vk::SemaphoreCreateInfo::builder();
+    let fence_info = vk::FenceCreateInfo::builder().flags(vk::FenceCreateFlags::SIGNALED);
 
     for _ in 0..MAX_FRAMES_IN_FLIGHT {
         data.image_available_semaphores
             .push(device.create_semaphore(&semaphore_info, None)?);
         data.render_finished_semaphores
             .push(device.create_semaphore(&semaphore_info, None)?);
+
+        data.in_flight_fences
+            .push(device.create_fence(&fence_info, None)?);
     }
 
+    data.images_in_flight = data
+        .swapchain_images
+        .iter()
+        .map(|_| vk::Fence::null())
+        .collect();
+
     Ok(())
 }