From a487ee41c8f42f7a228ea58981171977ed22aa20 Mon Sep 17 00:00:00 2001
From: Rory O'Connell <19547+RoryO@users.noreply.github.com>
Date: Thu, 6 Aug 2020 12:01:42 -0700
Subject: [PATCH] Update sdl example for best swapchain recreation

---
 examples/example_sdl_vulkan/main.cpp | 32 +++++++++++++---------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/examples/example_sdl_vulkan/main.cpp b/examples/example_sdl_vulkan/main.cpp
index 0a2ea9ee78d7..09ed77107080 100644
--- a/examples/example_sdl_vulkan/main.cpp
+++ b/examples/example_sdl_vulkan/main.cpp
@@ -37,6 +37,7 @@ static uint32_t                 g_MinImageCount = 2;
 static bool                     g_SwapChainRebuild = false;
 static int                      g_SwapChainResizeWidth = 0;
 static int                      g_SwapChainResizeHeight = 0;
+static SDL_Window*              g_Window;
 
 static void check_vk_result(VkResult err)
 {
@@ -313,6 +314,12 @@ static void FramePresent(ImGui_ImplVulkanH_Window* wd)
     info.pSwapchains = &wd->Swapchain;
     info.pImageIndices = &wd->FrameIndex;
     VkResult err = vkQueuePresentKHR(g_Queue, &info);
+    if(err == VK_ERROR_OUT_OF_DATE_KHR)
+    {
+        SDL_GetWindowSize(g_Window, &g_SwapChainResizeWidth, &g_SwapChainResizeHeight);
+        g_SwapChainRebuild = true;
+        return;
+    }
     check_vk_result(err);
     wd->SemaphoreIndex = (wd->SemaphoreIndex + 1) % wd->ImageCount; // Now we can use the next set of semaphores
 }
@@ -328,20 +335,20 @@ int main(int, char**)
 
     // Setup window
     SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_VULKAN | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
-    SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+Vulkan example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
+    g_Window = SDL_CreateWindow("Dear ImGui SDL2+Vulkan example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
 
     // Setup Vulkan
     uint32_t extensions_count = 0;
-    SDL_Vulkan_GetInstanceExtensions(window, &extensions_count, NULL);
+    SDL_Vulkan_GetInstanceExtensions(g_Window, &extensions_count, NULL);
     const char** extensions = new const char*[extensions_count];
-    SDL_Vulkan_GetInstanceExtensions(window, &extensions_count, extensions);
+    SDL_Vulkan_GetInstanceExtensions(g_Window, &extensions_count, extensions);
     SetupVulkan(extensions, extensions_count);
     delete[] extensions;
 
     // Create Window Surface
     VkSurfaceKHR surface;
     VkResult err;
-    if (SDL_Vulkan_CreateSurface(window, g_Instance, &surface) == 0)
+    if (SDL_Vulkan_CreateSurface(g_Window, g_Instance, &surface) == 0)
     {
         printf("Failed to create Vulkan surface.\n");
         return 1;
@@ -349,7 +356,7 @@ int main(int, char**)
 
     // Create Framebuffers
     int w, h;
-    SDL_GetWindowSize(window, &w, &h);
+    SDL_GetWindowSize(g_Window, &w, &h);
     ImGui_ImplVulkanH_Window* wd = &g_MainWindowData;
     SetupVulkanWindow(wd, surface, w, h);
 
@@ -365,7 +372,7 @@ int main(int, char**)
     //ImGui::StyleColorsClassic();
 
     // Setup Platform/Renderer bindings
-    ImGui_ImplSDL2_InitForVulkan(window);
+    ImGui_ImplSDL2_InitForVulkan(g_Window);
     ImGui_ImplVulkan_InitInfo init_info = {};
     init_info.Instance = g_Instance;
     init_info.PhysicalDevice = g_PhysicalDevice;
@@ -445,15 +452,6 @@ int main(int, char**)
             ImGui_ImplSDL2_ProcessEvent(&event);
             if (event.type == SDL_QUIT)
                 done = true;
-            if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_RESIZED && event.window.windowID == SDL_GetWindowID(window))
-            {
-                // Note: your own application may rely on SDL_WINDOWEVENT_MINIMIZED/SDL_WINDOWEVENT_RESTORED to skip updating all-together.
-                // Here ImGui_ImplSDL2_NewFrame() will set io.DisplaySize to zero which will disable rendering but let application run.
-                // Please note that you can't Present into a minimized window.
-                g_SwapChainResizeWidth = (int)event.window.data1;
-                g_SwapChainResizeHeight = (int)event.window.data2;
-                g_SwapChainRebuild = true;
-            }
         }
 
         // Resize swap chain?
@@ -467,7 +465,7 @@ int main(int, char**)
 
         // Start the Dear ImGui frame
         ImGui_ImplVulkan_NewFrame();
-        ImGui_ImplSDL2_NewFrame(window);
+        ImGui_ImplSDL2_NewFrame(g_Window);
         ImGui::NewFrame();
 
         // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
@@ -528,7 +526,7 @@ int main(int, char**)
     CleanupVulkanWindow();
     CleanupVulkan();
 
-    SDL_DestroyWindow(window);
+    SDL_DestroyWindow(g_Window);
     SDL_Quit();
 
     return 0;