ImGui-SFML

Library which allows you to use Dear ImGui with SFML

Based on this repository with big improvements and changes.

State of Development

Development is focused on version 3 in the master branch. No more features are planned for the 2.x release series.

Dependencies

• SFML >= 3.0.0
• Dear ImGui >= 1.91.1, < 1.92.0

Contributing

• The code is written in C++17 (SFML 3 uses C++17, Dear ImGui has started using C++11 since 2022)
• The code should be formatted via ClangFormat using .clang-format provided in the root of this repository

How-to

• CMake tutorial which also shows how to use ImGui-SFML with FetchContent
• Example project which sets up ImGui-SFML with FetchContent
• Detailed tutorial on Elias Daler's blog
• Using ImGui with modern C++ and STL
• Thread on SFML forums. Feel free to ask your questions there.

Building and integrating into your CMake project

It's highly recommended to use FetchContent or git submodules to get SFML and Dear ImGui into your build.

See this file - if you do something similar, you can then just link to ImGui-SFML as simply as:

target_link_libraries(game
  PUBLIC
    ImGui-SFML::ImGui-SFML
)

Integrating into your project manually

• Download ImGui
• Add Dear ImGui folder to your include directories
• Add imgui.cpp, imgui_widgets.cpp, imgui_draw.cpp and imgui_tables.cpp to your build/project
• Copy the contents of imconfig-SFML.h to your imconfig.h file. (to be able to cast ImVec2 to sf::Vector2f and vice versa)
• Add a folder which contains imgui-SFML.h to your include directories
• Add imgui-SFML.cpp to your build/project
• Link OpenGL if you get linking errors

Other ways to add to your project

Not recommended, as they're not maintained officially. Tend to lag behind and stay on older versions.

• Conan
• vcpkg
• Bazel

Using ImGui-SFML in your code

• Call ImGui::SFML::Init and pass your sf::Window + sf::RenderTarget or sf::RenderWindow there. You can create your font atlas and pass the pointer in Init too, otherwise the default internal font atlas will be created for you. Do this for each window you want to draw ImGui on.

• For each iteration of a game loop:

  • Poll and process events:

    while (const auto event = window.pollEvent()) {
        ImGui::SFML::ProcessEvent(window, *event);
        ...
    }
    

  • Call ImGui::SFML::Update(window, deltaTime) where deltaTime is sf::Time. You can also pass mousePosition and displaySize yourself instead of passing the window.

  • Call ImGui functions (ImGui::Begin(), ImGui::Button(), etc.)

  • Call ImGui::EndFrame after the last ImGui::End in your update function, if you update more than once before rendering. (e.g. fixed delta game loops)

  • Call ImGui::SFML::Render(window)

• Call ImGui::SFML::Shutdown() after window.close() has been called

  • Use ImGui::SFML::Shutdown(window) overload if you have multiple windows. After it's called one of the current windows will become a current "global" window. Call SetCurrentWindow to explicitly set which window will be used as default.

If you only draw ImGui widgets without any SFML stuff, then you'll might need to call window.resetGLStates() before rendering anything. You only need to do it once.

Example code

See example file here

#include "imgui.h"
#include "imgui-SFML.h"

#include <SFML/Graphics/CircleShape.hpp>
#include <SFML/Graphics/RenderWindow.hpp>
#include <SFML/System/Clock.hpp>
#include <SFML/Window/Event.hpp>

int main() {
    sf::RenderWindow window(sf::VideoMode({640, 480}), "ImGui + SFML = <3");
    window.setFramerateLimit(60);
    ImGui::SFML::Init(window);

    sf::CircleShape shape(100.f);
    shape.setFillColor(sf::Color::Green);

    sf::Clock deltaClock;
    while (window.isOpen()) {
        while (const auto event = window.pollEvent()) {
            ImGui::SFML::ProcessEvent(window, *event);

            if (event->is<sf::Event::Closed>()) {
                window.close();
            }
        }

        ImGui::SFML::Update(window, deltaClock.restart());

        ImGui::ShowDemoWindow();

        ImGui::Begin("Hello, world!");
        ImGui::Button("Look at this pretty button");
        ImGui::End();

        window.clear();
        window.draw(shape);
        ImGui::SFML::Render(window);
        window.display();
    }

    ImGui::SFML::Shutdown();
}

Fonts how-to

Default font is loaded if you don't pass false in ImGui::SFML::Init. Call ImGui::SFML::Init(window, false); if you don't want default font to be loaded.

• Load your fonts like this:

IO.Fonts->Clear(); // clear fonts if you loaded some before (even if only default one was loaded)
// IO.Fonts->AddFontDefault(); // this will load default font as well
IO.Fonts->AddFontFromFileTTF("font1.ttf", 8.f);
IO.Fonts->AddFontFromFileTTF("font2.ttf", 12.f);

ImGui::SFML::UpdateFontTexture(); // important call: updates font texture

• And use them like this:

ImGui::PushFont(ImGui::GetIO().Fonts->Fonts[0]);
ImGui::Button("Look at this pretty button");
ImGui::PopFont();

ImGui::PushFont(ImGui::GetIO().Fonts->Fonts[1]);
ImGui::TextUnformatted("IT WORKS!");
ImGui::PopFont();

The first loaded font is treated as the default one and doesn't need to be pushed with ImGui::PushFont.

Multiple windows

See examples/multiple_windows to see how you can create multiple SFML and run different ImGui contexts in them.

• Don't forget to run ImGui::SFML::Init(const sf::Window&) for each window you create. Same goes for ImGui::SFML::Shutdown(const sf::Window&)
• Instead of calling ImGui::SFML::ProcessEvent(sf::Event&), you need to call ImGui::SFML::ProcessEvent(const sf::Window&, const sf::Event&) overload for each window you create
• Call ImGui::SFML::SetCurrentWindow before calling any ImGui functions (e.g. ImGui::Begin, ImGui::Button etc.)
• Either call ImGui::Render(sf::RenderWindow&) overload for each window or manually do this:

  SetCurrentWindow(window);
  ... // your custom rendering
  ImGui::Render();
  
  SetCurrentWindow(window2);
  ... // your custom rendering
  ImGui::Render();
  

• When closing everything: don't forget to close all windows using SFML's sf::Window::Close and then call ImGui::SFML::Shutdown to remote all ImGui-SFML window contexts and other data.

SFML related ImGui overloads / new widgets

There are some useful overloads implemented for SFML objects (see imgui-SFML.h for other overloads):

ImGui::Image(const sf::Sprite& sprite);
ImGui::Image(const sf::Texture& texture);
ImGui::Image(const sf::RenderTexture& texture);

ImGui::ImageButton(const sf::Sprite& sprite);
ImGui::ImageButton(const sf::Texture& texture);
ImGui::ImageButton(const sf::RenderTexture& texture);

A note about sf::RenderTexture

sf::RenderTexture's texture is stored with pixels flipped upside down. To display it properly when drawing ImGui::Image or ImGui::ImageButton, use overloads for sf::RenderTexture:

sf::RenderTexture texture;
sf::Sprite sprite(texture.getTexture());
ImGui::Image(texture);              // OK
ImGui::Image(sprite);               // NOT OK
ImGui::Image(texture.getTexture()); // NOT OK

If you want to draw only a part of sf::RenderTexture and you're trying to use sf::Sprite the texture will be displayed upside-down. To prevent this, you can do this:

// make a normal sf::Texture from sf::RenderTexture's flipped texture
sf::Texture texture(renderTexture.getTexture());

sf::Sprite sprite(texture);
ImGui::Image(sprite); // the texture is displayed properly

For more notes see this issue.

Mouse cursors

You can change your cursors in ImGui like this:

ImGui::SetMouseCursor(ImGuiMouseCursor_TextInput);

By default, your system cursor will change and will be rendered by your system. If you want SFML to draw your cursor with default ImGui cursors (the system cursor will be hidden), do this:

ImGuiIO& io = ImGui::GetIO();
io.MouseDrawCursor = true;

To hide the mouse cursor you'll need to set both the custor style to none and the imgui's drawn cursor to false (This also needs to be done every frame):

ImGui::SetMouseCursor(ImGuiMouseCursor_None);
io.MouseDrawCursor = false;

You can also completely disable ImGui's control over the system cursor by setting the appropriate flag:

io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange;

Keyboard/Gamepad navigation

Starting with ImGui 1.60, there's a feature to control ImGui with keyboard and gamepad. To use keyboard navigation, you just need to do this:

ImGuiIO& io = ImGui::GetIO();
io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;

Gamepad navigation requires more work, unless you have XInput gamepad, in which case the mapping is automatically set for you. But you can still set it up for your own gamepad easily, just take a look how it's done for the default mapping here. And then you need to do this:

ImGuiIO& io = ImGui::GetIO();
io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;

By default, the first active joystick is used for navigation, but you can set joystick id explicitly like this:

ImGui::SFML::SetActiveJoystickId(5);

High DPI screens

As SFML is not currently DPI aware, your GUI may show at the incorrect scale. This is particularly noticeable on systems with "Retina" / "4K" / "UHD" displays.

To work around this on macOS, you can create an app bundle (as opposed to just the exe) then modify the info.plist so that "High Resolution Capable" is set to "NO".

Another option to help ameliorate this, at least for getting started and for the common ImGui use-case of "developer/debug/building UI", is to explore FontGlobalScale:

ImGuiIO& io = ImGui::GetIO();
io.FontGlobalScale = 2.0; // or any other value hardcoded or loaded from your config logic

License

This library is licensed under the MIT License, see LICENSE for more information.