disp/vulkan: Fix suboptimal swapchain handling

When vkAcquireNextImage() returns VK_SUBOPTIMAL_KHR it means that a valid
usable image was still acquired and that means that the
acquire_samaphore is pending and signalled as normal.

This means we cannot just recreate the swapchain and reuse it to acquire
an image from the new swapchain as VulkanDisplay::display_queued_image()
was doing, because the spec states that the semaphore must be unsignaled
and not pending.

The fix here is to render and display the suboptimal image as normal and
set a flag to immediately return swapchain_image_out_of_date to trigger
a swapchain recreation on the next frame.

Author: mpiatka

src/video_display/vulkan/vulkan_context.cpp

@@ -544,16 +544,23 @@ void VulkanContext::recreate_swapchain(WindowParameters parameters, vk::RenderPa
         create_swap_chain(std::move(old_swap_chain));
         create_swapchain_views(device, swapchain, swapchain_atributes.format.format, swapchain_images);
         create_framebuffers(render_pass);
+        swapchain_was_suboptimal = false;
 }
 
-uint32_t VulkanContext::acquire_next_swapchain_image(vk::Semaphore acquire_semaphore) const {
+uint32_t VulkanContext::acquire_next_swapchain_image(vk::Semaphore acquire_semaphore) {
+        if(swapchain_was_suboptimal){
+                return swapchain_image_out_of_date;
+        }
+
         constexpr uint64_t timeout = 1'000'000'000; // 1s = 1 000 000 000 nanoseconds
         uint32_t image_index;
         auto acquired = device.acquireNextImageKHR(swapchain, timeout, acquire_semaphore, nullptr, &image_index);
         switch (acquired) {
                 case vk::Result::eSuccess:
                         break;
-                case vk::Result::eSuboptimalKHR: [[fallthrough]];
+                case vk::Result::eSuboptimalKHR:
+                        swapchain_was_suboptimal = true;
+                        break;
                 case vk::Result::eErrorOutOfDateKHR:
                         image_index = swapchain_image_out_of_date;
                         break;

src/video_display/vulkan/vulkan_context.hpp

@@ -158,6 +158,7 @@ class VulkanContext {
         vk::PresentModeKHR preferred_present_mode{};
 
         vulkan_display::WindowParameters window_parameters;
+        bool swapchain_was_suboptimal = false;
 public:
         //getters
         uint32_t get_vulkan_version() const { return vulkan_version; }
@@ -199,7 +200,7 @@ class VulkanContext {
 
         void create_framebuffers(vk::RenderPass render_pass);
 
-        uint32_t acquire_next_swapchain_image(vk::Semaphore acquire_semaphore) const;
+        uint32_t acquire_next_swapchain_image(vk::Semaphore acquire_semaphore);
 
         vk::Framebuffer get_framebuffer(uint32_t framebuffer_id) {
                 return swapchain_images[framebuffer_id].framebuffer;