Assert when shutting down and recreating backend

[metarutaiga]

Version/Branch of Dear ImGui:

Version: 1.73
Branch: viewport

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_win32.cpp
Compiler: msvc_v142
Operating System: win10

My Issue/Question:

I implement a graphic library that it can change APIs in runtime.
But it always assert when recreating imgui.
I modified it below, but it's not a good method.
Has any good idea to resolve this assert?

Standalone, minimal, complete and verifiable example:
-- ImGuiViewport* main_viewport = ImGui::GetMainViewport();
++ ImGuiViewportP* main_viewport = (ImGuiViewportP*)ImGui::GetMainViewport();
++ main_viewport->PlatformWindowCreated = true;

[ocornut]

Please:

• Actually specify WHAT is asserting, including a callstack. You haven't mentioned what the assert is.
• Provide a repro or pseudo code to explain what you are doing.

TL;DR; we need more context please.

[metarutaiga]

My recreating method :
ImGui_ImplXX_Shutdown();
ImGui_ImplWin32_Shutdown();
ImGui_ImplWin32_Init(hWnd);
ImGui_ImplXX_Init(g_instance, 0, g_device);

I don't run ImGui::DestroyContext(); / ImGui::CreateContext();
And the PlatformWindowCreated of main-viewport is initialized in ImGui::CreateContext(); only.
So it would be assert the problem.

[kudaba]

I think you're hitting the crash that I fixed here: #2698, at least I think you're using the vulkan backend, you should include that in reports.

[ocornut]

Pushed a fix for this issue.
Ideally we may want this field to be set/cleared by the platform back-end. We'll probably refactor this when working on #2471.