ocornut
User input is not getting accepted/handled caused when dockspace and viewports are enabled.
Version/Branch of Dear ImGui:
docking
Back-ends:
imgui_impl_SDL3.cpp + imgui_impl_OpenGL3.cpp
Compiler, OS:
Windows 11 + MSVC 2022
Full config/build information:
No response
Details:
I have enabled Docking and Viewports in the code and for some reason if/when i drag one of the windows (created by ImGui::begin()) to the left side of the main window (created by SDL) [and it almost feels like it happens only on left side.. i was never able to make the issue happen when i move the window right hand side] it kind of get stuck and then doesn't accept any user input (keyboard typing and mouse events somtimes). It's hard to explain what's going on (i am non-native english person). So i used OBS to record what's going on.
Once that stucking thing happen it stops accepting user commands even after restarting the application. (In the code i wrote). In the ImGuiExample code. same thing happens. But after i restart the app it starts accepting user events again.
Screenshots/Video:
https://github.com/user-attachments/assets/c3c44075-c588-4622-9919-3ced8a07bfbf https://github.com/user-attachments/assets/39fd0b5a-f930-4909-a413-3fc54637cc4e
Minimal, Complete and Verifiable Example code:
I can replicate it in the Demo code as well. So i don't think the code is needed.. But.. i will share how i setup the backends. Since that part is slightly altered.
auto init_gui_backend(const char *in_window_name) -> SDLInfo
{ // Setup SDL
// [If using SDL_MAIN_USE_CALLBACKS: all code below until the main loop starts would likely be your SDL_AppInit() function]
if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_GAMEPAD))
{
OMEGA_LOGE("Error: SDL_Init(): %s\n", SDL_GetError());
return {nullptr, nullptr};
}
#if __APPLE__
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
#else
// GL 3.0 + GLSL 130
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
#endif
// Create window with graphics context
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
Uint32 window_flags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIDDEN;
SDL_Window *window = SDL_CreateWindow(in_window_name, 1280, 720, window_flags);
if (window == nullptr)
{
OMEGA_LOGE("Error: SDL_CreateWindow(): %s\n", SDL_GetError());
return {nullptr, nullptr};
}
SDL_SetWindowPosition(window, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED);
SDL_GLContext gl_context = SDL_GL_CreateContext(window);
if (gl_context == nullptr)
{
OMEGA_LOGE("Error: SDL_GL_CreateContext(): %s\n", SDL_GetError());
return {nullptr, nullptr};
}
SDL_GL_MakeCurrent(window, gl_context);
SDL_GL_SetSwapInterval(1); // Enable vsync
SDL_ShowWindow(window);
// Initialize GLAD
if (!gladLoadGLLoader((GLADloadproc)SDL_GL_GetProcAddress))
{
OMEGA_LOGE("Failed to initialize GLAD");
SDL_GL_DestroyContext(gl_context);
SDL_DestroyWindow(window);
SDL_Quit();
return {nullptr, nullptr};
}
return {window, gl_context};
}
auto init_imgui(SDLInfo *info) -> void
{
// Setup Dear ImGui context
IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO &io = ImGui::GetIO();
(void)io;
io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls
io.ConfigFlags |= ImGuiConfigFlags_DockingEnable; // Enable Docking
io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable; // Enable Multi-Viewport / Platform Windows
//io.ConfigViewportsNoAutoMerge = true;
//io.ConfigViewportsNoTaskBarIcon = true;
// Setup Dear ImGui style
ImGui::StyleColorsDark();
// ImGui::StyleColorsLight();
// When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
ImGuiStyle &style = ImGui::GetStyle();
if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
{
style.WindowRounding = 0.0f;
style.Colors[ImGuiCol_WindowBg].w = 1.0f;
}
// Setup Platform/Renderer backends
ImGui_ImplSDL3_InitForOpenGL(info->sdl_window, info->gl_context);
ImGui_ImplOpenGL3_Init(glsl_version);
// Load Fonts
// - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
// - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
// - If the file cannot be loaded, the function will return a nullptr. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
// - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
// - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
// - Read 'docs/FONTS.md' for more instructions and details.
// - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
// - Our Emscripten build process allows embedding fonts to be accessible at runtime from the "fonts/" folder. See Makefile.emscripten for details.
// io.Fonts->AddFontDefault();
// io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
// io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
// io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
// io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
// ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, nullptr, io.Fonts->GetGlyphRangesJapanese());
// IM_ASSERT(font != nullptr);
}
I can replicate it in the Demo code as well.
Just to clarify, does this happen to you with an unmodified version of example_sdl3_opengl3? (That's what I initially thought you meant, but your second video made me think otherwise.)
I can replicate it in the Demo code as well.
Just to clarify, does this happen to you with an unmodified version of
example_sdl3_opengl3? (That's what I initially thought you meant, but your second video made me think otherwise.)
Both my backend initialization (SDL3 and OpenGL3) as well as the initialization from the example code cause the same issue..
#include "imgui.h"
#include "imgui_impl_opengl3.h"
#include "imgui_impl_sdl3.h"
#include <SDL3/SDL.h>
#include <stdio.h>
#if defined(IMGUI_IMPL_OPENGL_ES2)
#include <SDL3/SDL_opengles2.h>
#else
#include <SDL3/SDL_opengl.h>
#endif
#ifdef __EMSCRIPTEN__
#include "../libs/emscripten/emscripten_mainloop_stub.h"
#endif
auto main() -> int
{ // Setup SDL
// [If using SDL_MAIN_USE_CALLBACKS: all code below until the main loop starts would likely be your SDL_AppInit() function]
if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_GAMEPAD))
{
printf("Error: SDL_Init(): %s\n", SDL_GetError());
return -1;
}
// Decide GL+GLSL versions
#if defined(IMGUI_IMPL_OPENGL_ES2)
// GL ES 2.0 + GLSL 100 (WebGL 1.0)
const char *glsl_version = "#version 100";
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
#elif defined(IMGUI_IMPL_OPENGL_ES3)
// GL ES 3.0 + GLSL 300 es (WebGL 2.0)
const char *glsl_version = "#version 300 es";
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
#elif defined(__APPLE__)
// GL 3.2 Core + GLSL 150
const char *glsl_version = "#version 150";
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG); // Always required on Mac
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
#else
// GL 3.0 + GLSL 130
const char *glsl_version = "#version 130";
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
#endif
// Create window with graphics context
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
Uint32 window_flags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIDDEN;
SDL_Window *window = SDL_CreateWindow("Dear ImGui SDL3+OpenGL3 example", 1280, 720, window_flags);
if (window == nullptr)
{
printf("Error: SDL_CreateWindow(): %s\n", SDL_GetError());
return -1;
}
SDL_SetWindowPosition(window, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED);
SDL_GLContext gl_context = SDL_GL_CreateContext(window);
if (gl_context == nullptr)
{
printf("Error: SDL_GL_CreateContext(): %s\n", SDL_GetError());
return -1;
}
SDL_GL_MakeCurrent(window, gl_context);
SDL_GL_SetSwapInterval(1); // Enable vsync
SDL_ShowWindow(window);
// Setup Dear ImGui context
IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO &io = ImGui::GetIO();
(void)io;
io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls
io.ConfigFlags |= ImGuiConfigFlags_DockingEnable; // Enable Docking
io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable; // Enable Multi-Viewport / Platform Windows
// io.ConfigViewportsNoAutoMerge = true;
// io.ConfigViewportsNoTaskBarIcon = true;
// Setup Dear ImGui style
ImGui::StyleColorsDark();
// ImGui::StyleColorsLight();
// When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
ImGuiStyle &style = ImGui::GetStyle();
if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
{
style.WindowRounding = 0.0f;
style.Colors[ImGuiCol_WindowBg].w = 1.0f;
}
// Setup Platform/Renderer backends
ImGui_ImplSDL3_InitForOpenGL(window, gl_context);
ImGui_ImplOpenGL3_Init(glsl_version);
// Load Fonts
// - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
// - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
// - If the file cannot be loaded, the function will return a nullptr. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
// - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
// - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
// - Read 'docs/FONTS.md' for more instructions and details.
// - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
// - Our Emscripten build process allows embedding fonts to be accessible at runtime from the "fonts/" folder. See Makefile.emscripten for details.
// io.Fonts->AddFontDefault();
// io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
// io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
// io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
// io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
// ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, nullptr, io.Fonts->GetGlyphRangesJapanese());
// IM_ASSERT(font != nullptr);
// Our state
bool show_demo_window = true;
bool show_another_window = false;
ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
// Main loop
bool done = false;
#ifdef __EMSCRIPTEN__
// For an Emscripten build we are disabling file-system access, so let's not attempt to do a fopen() of the imgui.ini file.
// You may manually call LoadIniSettingsFromMemory() to load settings from your own storage.
io.IniFilename = nullptr;
EMSCRIPTEN_MAINLOOP_BEGIN
#else
while (!done)
#endif
{
// Poll and handle events (inputs, window resize, etc.)
// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
// [If using SDL_MAIN_USE_CALLBACKS: call ImGui_ImplSDL3_ProcessEvent() from your SDL_AppEvent() function]
SDL_Event event;
while (SDL_PollEvent(&event))
{
ImGui_ImplSDL3_ProcessEvent(&event);
if (event.type == SDL_EVENT_QUIT)
done = true;
if (event.type == SDL_EVENT_WINDOW_CLOSE_REQUESTED && event.window.windowID == SDL_GetWindowID(window))
done = true;
}
// [If using SDL_MAIN_USE_CALLBACKS: all code below would likely be your SDL_AppIterate() function]
if (SDL_GetWindowFlags(window) & SDL_WINDOW_MINIMIZED)
{
SDL_Delay(10);
continue;
}
// Start the Dear ImGui frame
ImGui_ImplOpenGL3_NewFrame();
ImGui_ImplSDL3_NewFrame();
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!).
if (show_demo_window)
ImGui::ShowDemoWindow(&show_demo_window);
// 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
{
static float f = 0.0f;
static int counter = 0;
ImGui::Begin("Hello, world!"); // Create a window called "Hello, world!" and append into it.
ImGui::Text("This is some useful text."); // Display some text (you can use a format strings too)
ImGui::Checkbox("Demo Window", &show_demo_window); // Edit bools storing our window open/close state
ImGui::Checkbox("Another Window", &show_another_window);
ImGui::SliderFloat("float", &f, 0.0f, 1.0f); // Edit 1 float using a slider from 0.0f to 1.0f
ImGui::ColorEdit3("clear color", (float *)&clear_color); // Edit 3 floats representing a color
if (ImGui::Button("Button")) // Buttons return true when clicked (most widgets return true when edited/activated)
counter++;
ImGui::SameLine();
ImGui::Text("counter = %d", counter);
ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
ImGui::End();
}
// 3. Show another simple window.
if (show_another_window)
{
ImGui::Begin("Another Window", &show_another_window); // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
ImGui::Text("Hello from another window!");
if (ImGui::Button("Close Me"))
show_another_window = false;
ImGui::End();
}
// Rendering
ImGui::Render();
glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
glClear(GL_COLOR_BUFFER_BIT);
ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
// Update and Render additional Platform Windows
// (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
// For this specific demo app we could also call SDL_GL_MakeCurrent(window, gl_context) directly)
if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
{
SDL_Window *backup_current_window = SDL_GL_GetCurrentWindow();
SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
ImGui::UpdatePlatformWindows();
ImGui::RenderPlatformWindowsDefault();
SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
}
SDL_GL_SwapWindow(window);
}
#ifdef __EMSCRIPTEN__
EMSCRIPTEN_MAINLOOP_END;
#endif
// Cleanup
// [If using SDL_MAIN_USE_CALLBACKS: all code below would likely be your SDL_AppQuit() function]
ImGui_ImplOpenGL3_Shutdown();
ImGui_ImplSDL3_Shutdown();
ImGui::DestroyContext();
SDL_GL_DestroyContext(gl_context);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
i have just directly copy pasted the example code to the project. and there are no code written by me running. But the issues i have shown in the videos persist.
I can replicate it in the Demo code as well.
Just to clarify, does this happen to you with an unmodified version of
example_sdl3_opengl3? (That's what I initially thought you meant, but your second video made me think otherwise.)
I did more testing. Nothing seems to fix the issue. Just to see whether changing the backend to something else changes anything i downgraded the SDL version to SDL2. That fixed the issue. Now the inputs are working.
It seems like the issue is coming from either the SDL3 itself or the backend implementation of SDL3 in imgui repo. Not sure where though. i will look into that and maybe do a pull request if i find/fix anything on the imGui side.
But for now the issue is resolved by downgrading the SDL3(origin/release-3.2.x) to SDL2 (origin/release-2.32.x)
We can confirm this became an issue last week when we updated from 1.91.9 to fcdaa327938741b0359ffde68ba9253ac1ace4a1 (this occurs both on sdl3 3.2.8 and 3.2.10)
It's related to the imgui sdl3 backend changes made I reckon
Could you both also clarify which SDL3 version do you have this bug?
We can confirm this became an issue last week when we updated from 1.91.8 to https://github.com/ocornut/imgui/commit/fcdaa327938741b0359ffde68ba9253ac1ace4a1. It's related to the imgui sdl3 backend changes made I reckon
Could you use git bisect on your copy of the imgui repo to narrow down to the commit ?
Note that on April 23 we pushed a bug https://github.com/ocornut/imgui/commit/2a000ee0918f5e80690c0f902124fd437c9e7509 which was reverted on April 25 https://github.com/ocornut/imgui/commit/fe298cf98423825d1547b821e4849bd3d2be46bc so any version between those 2 commits would be faulty.
However fcdaa327938741b0359ffde68ba9253ac1ace4a1 seems to be after.
You can also use Tools->Debug Log->[X] IO to visualize IO events and try to understand what is happening when it breaks.
One potential culprit :
- [1] https://github.com/ocornut/imgui/commit/aa83d5d455dcab4b65cca71efd6291f943feea67 try using
SDL_CaptureMouse(bd->MouseButtonsDown != 0);
I am struggling to find what else could have caused this. Please git bisect or provide more informaiton. Thanks!