Examples: Vulkan: fill Subpass and MSAASamples to increase discoverability (#4886) + IO docs update (#4858)

https://github.com/mosra/magnum-integration/pull/89

backends/imgui_impl_vulkan.h

@@ -6,7 +6,7 @@
 // Missing features:
 //  [ ] Renderer: User texture binding. Changes of ImTextureID aren't supported by this backend! See https://github.com/ocornut/imgui/pull/914
 
-// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this. 
+// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
 // Read online: https://github.com/ocornut/imgui/tree/master/docs
@@ -56,7 +56,7 @@ struct ImGui_ImplVulkan_InitInfo
     uint32_t                        Subpass;
     uint32_t                        MinImageCount;          // >= 2
     uint32_t                        ImageCount;             // >= MinImageCount
-    VkSampleCountFlagBits           MSAASamples;            // >= VK_SAMPLE_COUNT_1_BIT
+    VkSampleCountFlagBits           MSAASamples;            // >= VK_SAMPLE_COUNT_1_BIT (0 -> default to VK_SAMPLE_COUNT_1_BIT)
     const VkAllocationCallbacks*    Allocator;
     void                            (*CheckVkResultFn)(VkResult err);
 };

docs/CHANGELOG.txt

@@ -48,11 +48,13 @@ Breaking Changes:
     - IsKeyDown(), IsKeyPressed(), IsKeyReleased(), GetKeyPressedAmount().
   - All backends were updated to use io.AddKeyEvent().
   - Backward compatibility:
-    - Old backends populating those arrays will still work! (for a while)
+    - Old backends populating those arrays should still work! (for a while)
     - Calling e.g. IsKeyPressed(MY_NATIVE_KEY_XXX) will still work! (for a while)
     - Those legacy arrays will only be disabled if '#define IMGUI_DISABLE_OBSOLETE_KEYIO' is set in your imconfig.
       In a few versions, IMGUI_DISABLE_OBSOLETE_FUNCTIONS will automatically enable IMGUI_DISABLE_OBSOLETE_KEYIO,
       so this will be moved into the regular obsolescence path.
+    - BREAKING: If your custom backend used ImGuiKey as mock native indices (e.g. "io.KeyMap[ImGuiKey_A] = ImGuiKey_A")
+      this is a use case that will now assert and be breaking for your old backend.
   - Transition guide:
      - IsKeyPressed(MY_NATIVE_KEY_XXX)           -> use IsKeyPressed(ImGuiKey_XXX)
      - IsKeyPressed(GetKeyIndex(ImGuiKey_XXX))   -> use IsKeyPressed(ImGuiKey_XXX)

examples/example_glfw_vulkan/main.cpp

@@ -404,9 +404,11 @@ int main(int, char**)
     init_info.Queue = g_Queue;
     init_info.PipelineCache = g_PipelineCache;
     init_info.DescriptorPool = g_DescriptorPool;
-    init_info.Allocator = g_Allocator;
+    init_info.Subpass = 0;
     init_info.MinImageCount = g_MinImageCount;
     init_info.ImageCount = wd->ImageCount;
+    init_info.MSAASamples = VK_SAMPLE_COUNT_1_BIT;
+    init_info.Allocator = g_Allocator;
     init_info.CheckVkResultFn = check_vk_result;
     ImGui_ImplVulkan_Init(&init_info, wd->RenderPass);
 

examples/example_sdl_vulkan/main.cpp

@@ -396,9 +396,11 @@ int main(int, char**)
     init_info.Queue = g_Queue;
     init_info.PipelineCache = g_PipelineCache;
     init_info.DescriptorPool = g_DescriptorPool;
-    init_info.Allocator = g_Allocator;
+    init_info.Subpass = 0;
     init_info.MinImageCount = g_MinImageCount;
     init_info.ImageCount = wd->ImageCount;
+    init_info.MSAASamples = VK_SAMPLE_COUNT_1_BIT;
+    init_info.Allocator = g_Allocator;
     init_info.CheckVkResultFn = check_vk_result;
     ImGui_ImplVulkan_Init(&init_info, wd->RenderPass);
 

imgui.cpp

@@ -390,6 +390,7 @@ CODE
                         - IsKeyPressed(MY_NATIVE_KEY_XXX)              -> use IsKeyPressed(ImGuiKey_XXX)
                         - IsKeyPressed(GetKeyIndex(ImGuiKey_XXX))      -> use IsKeyPressed(ImGuiKey_XXX)
                         - Backend writing to io.KeyMap[],io.KeysDown[] -> backend should call io.AddKeyEvent()
+                     - one case won't work with backward compatibility: if your custom backend used ImGuiKey as mock native indices (e.g. "io.KeyMap[ImGuiKey_A] = ImGuiKey_A") because those values are now larger than the legacy KeyDown[] array. Will assert.
                      - inputs: added io.AddKeyModsEvent() instead of writing directly to io.KeyCtrl, io.KeyShift, io.KeyAlt, io.KeySuper.
  - 2022/01/05 (1.87) - inputs: renamed ImGuiKey_KeyPadEnter to ImGuiKey_KeypadEnter to align with new symbols. Kept redirection enum.
  - 2022/01/05 (1.87) - removed io.ImeSetInputScreenPosFn() in favor of more flexible io.SetPlatformImeDataFn(). Removed 'void* io.ImeWindowHandle' in favor of writing to 'void* ImGuiViewport::PlatformHandleRaw'.