Merge #220

220: Support more than one frame in flight r=kvark a=kvark

Fixes #219 
![portability-dota2](https://user-images.githubusercontent.com/107301/92435144-9d3e6f80-f16f-11ea-91d3-8bffbb36dc44.jpg)


Co-authored-by: Dzmitry Malyshau <kvarkus@gmail.com>

libportability-gfx/src/impls.rs

@@ -4378,9 +4378,9 @@ pub unsafe extern "C" fn gfxCreateSwapchainKHR(
             let swapchain = Swapchain {
                 gpu,
                 surface: info.surface,
-                count: info.minImageCount as u8,
+                count: info.minImageCount,
                 current_index: 0,
-                active: None,
+                active: Vec::new(),
                 lazy_framebuffers: Mutex::new(Vec::with_capacity(1)),
             };
             *pSwapchain = Handle::new(swapchain);
@@ -4419,7 +4419,7 @@ pub unsafe extern "C" fn gfxGetSwapchainImagesKHR(
     debug_assert!(!pSwapchainImageCount.is_null());
 
     let swapchain_image_count = &mut *pSwapchainImageCount;
-    let available_images = swapchain.count as u32;
+    let available_images = swapchain.count;
 
     if pSwapchainImages.is_null() {
         // If NULL the number of presentable images is returned.
@@ -4427,7 +4427,7 @@ pub unsafe extern "C" fn gfxGetSwapchainImagesKHR(
     } else {
         *swapchain_image_count = available_images.min(*swapchain_image_count);
 
-        for frame in 0..*swapchain_image_count as u8 {
+        for frame in 0..*swapchain_image_count {
             *pSwapchainImages.offset(frame as isize) =
                 Handle::new(Image::SwapchainFrame { swapchain, frame });
         }
@@ -4663,17 +4663,12 @@ pub unsafe extern "C" fn gfxAcquireNextImageKHR(
         sem.is_fake = true;
     }
 
-    if let Some(_old_frame) = swapchain.active.take() {
-        warn!(
-            "Swapchain frame {} was not presented!",
-            swapchain.current_index
-        );
-    }
     match swapchain.surface.acquire_image(timeout) {
         Ok((frame, suboptimal)) => {
-            swapchain.current_index = (swapchain.current_index + 1) % swapchain.count;
+            let index = (swapchain.current_index + 1) % swapchain.count;
-            swapchain.active = Some(frame);
+            swapchain.active.push((index, frame));
-            *pImageIndex = swapchain.current_index as u32;
+            *pImageIndex = index;
+            swapchain.current_index = index;
             match suboptimal {
                 Some(_) => VkResult::VK_SUBOPTIMAL_KHR,
                 None => VkResult::VK_SUCCESS,
@@ -4704,17 +4699,18 @@ pub unsafe extern "C" fn gfxQueuePresentKHR(
         );
     }
 
-    for (swapchain, index) in swapchain_slice.iter().zip(index_slice) {
+    for (swapchain, &index) in swapchain_slice.iter().zip(index_slice) {
         let sc = swapchain.as_mut().unwrap();
-        let frame = sc.active.take().expect("Frame was not acquired properly!");
+        let active_pos = sc
-        if sc.current_index == *index as u8 {
+            .active
+            .iter()
+            .position(|&(frame, _)| frame == index)
+            .expect("Frame was not acquired properly!");
+        let frame = sc.active.swap_remove(active_pos).1;
         let sem = wait_semaphores.first().map(|s| &s.raw);
         if let Err(_) = queue.present(&mut *sc.surface, frame, sem) {
             return VkResult::VK_ERROR_SURFACE_LOST_KHR;
         }
-        } else {
-            warn!("Swapchain frame {} is stale, can't be presented.", *index);
-        }
         for framebuffer in sc.lazy_framebuffers.lock().drain(..) {
             sc.gpu.device.destroy_framebuffer(framebuffer)
         }

libportability-gfx/src/lib.rs

@@ -117,7 +117,7 @@ pub enum Image<B: hal::Backend> {
     },
     SwapchainFrame {
         swapchain: VkSwapchainKHR,
-        frame: u8,
+        frame: hal::window::SwapImageIndex,
     },
 }
 
@@ -137,7 +137,7 @@ pub enum ImageView {
     Native(<B as hal::Backend>::ImageView),
     SwapchainFrame {
         swapchain: VkSwapchainKHR,
-        frame: u8,
+        frame: hal::window::SwapImageIndex,
     },
 }
 
@@ -194,11 +194,12 @@ impl Framebuffer {
                         frame,
                     } => {
                         use std::borrow::Borrow;
-                        debug_assert_eq!(frame, swapchain.current_index);
                         swapchain
                             .active
-                            .as_ref()
+                            .iter()
+                            .find(|&&(index, _)| index == frame)
                             .expect("Swapchain frame isn't acquired")
+                            .1
                             .borrow()
                     }
                 });
@@ -246,9 +247,12 @@ pub type VkSwapchainKHR = Handle<Swapchain<B>>;
 pub struct Swapchain<B: hal::Backend> {
     gpu: VkDevice,
     surface: VkSurfaceKHR,
-    count: u8,
+    count: hal::window::SwapImageIndex,
-    current_index: u8,
+    current_index: hal::window::SwapImageIndex,
-    active: Option<<B::Surface as hal::window::PresentationSurface<B>>::SwapchainImage>,
+    active: Vec<(
+        hal::window::SwapImageIndex,
+        <B::Surface as hal::window::PresentationSurface<B>>::SwapchainImage,
+    )>,
     lazy_framebuffers: parking_lot::Mutex<Vec<<B as hal::Backend>::Framebuffer>>,
 }