nullpointer when shutting down multi window context #8676
Description
Version/Branch of Dear ImGui:
Version 1.92.0, Branch: docking
Back-ends:
imgui_impl_glfw.cpp + imgui_impl_opengl3.cpp
Compiler, OS:
Windows 11 + MSVC 2022
Full config/build information:
Dear ImGui 1.92.0 WIP (19197)
--------------------------------
sizeof(size_t): 8, sizeof(ImDrawIdx): 2, sizeof(ImDrawVert): 20
define: __cplusplus=199711
define: _WIN32
define: _WIN64
define: _MSC_VER=1944
define: _MSVC_LANG=201402
define: IMGUI_HAS_VIEWPORT
define: IMGUI_HAS_DOCK
--------------------------------
io.BackendPlatformName: imgui_impl_glfw (3500)
io.BackendRendererName: imgui_impl_opengl3
io.ConfigFlags: 0x00000481
NavEnableKeyboard
DockingEnable
ViewportsEnable
io.ConfigViewportsNoDecoration
io.ConfigNavCaptureKeyboard
io.ConfigInputTextCursorBlink
io.ConfigWindowsResizeFromEdges
io.ConfigMemoryCompactTimer = 60.0
io.BackendFlags: 0x00001C0E
HasMouseCursors
HasSetMousePos
PlatformHasViewports
HasMouseHoveredViewport
RendererHasVtxOffset
RendererHasViewports
--------------------------------
io.Fonts: 1 fonts, Flags: 0x00000000, TexSize: 512,64
io.DisplaySize: 640.00,480.00
io.DisplayFramebufferScale: 1.00,1.00
--------------------------------
style.WindowPadding: 8.00,8.00
style.WindowBorderSize: 1.00
style.FramePadding: 4.00,3.00
style.FrameRounding: 0.00
style.FrameBorderSize: 0.00
style.ItemSpacing: 8.00,4.00
style.ItemInnerSpacing: 4.00,4.00
Details:
I am trying to create multiple glfw windows, each with their own imgui context to make imgui work with multiple windows.
one of the problems that i found is that if i close one window, everything works fine, but when i close the other window, there is a null pointer error
it happens in this line
callstack of the example program i have attached:
> tmp.exe!ImGui_ImplGlfw_WndProc(HWND__ * hWnd, unsigned int msg, unsigned __int64 wParam, __int64 lParam) Line 1447 C++
user32.dll!00007ffe03fee83a() Unknown
user32.dll!00007ffe03fee11c() Unknown
user32.dll!00007ffe0402a516() Unknown
ntdll.dll!00007ffe06385f94() Unknown
win32u.dll!00007ffe03fb2534() Unknown
tmp.exe!_glfwDestroyWindowWin32(_GLFWwindow * window) Line 1575 C
tmp.exe!glfwDestroyWindow(GLFWwindow * handle) Line 486 C
tmp.exe!main() Line 49 C++
Screenshots/Video:
No response
Minimal, Complete and Verifiable Example code:
#include <imgui.h>
#include <backends/imgui_impl_glfw.h>
#include <backends/imgui_impl_opengl3.h>
#include <GLFW/glfw3.h>
int main() {
if (!glfwInit())
return -1;
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
struct windowContext {
GLFWwindow* window;
ImGuiContext* context;
};
windowContext windows[2] = {};
for (int i = 0; i < 2; i++) {
windows[i].window = glfwCreateWindow(640, 480, "title", nullptr, nullptr);
if (windows[i].window == nullptr) {
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(windows[i].window);
glfwSwapInterval(1);
windows[i].context = ImGui::CreateContext();
ImGui::SetCurrentContext(windows[i].context);
ImGuiIO& io = ImGui::GetIO();
io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;
ImGui::StyleColorsDark();
ImGui_ImplGlfw_InitForOpenGL(windows[i].window, false);
ImGui_ImplOpenGL3_Init("#version 430");
}
//for (int i = 0; i < 2; i++) { // works
for (int i = 1; i >= 0; i--) { // doesn't work
ImGui::SetCurrentContext(windows[i].context);
ImGui_ImplOpenGL3_Shutdown();
ImGui_ImplGlfw_Shutdown();
glfwDestroyWindow(windows[i].window);
}
glfwTerminate();
return 0;
}