diff options
Diffstat (limited to 'src/imgui/docs/BACKENDS.md')
| -rw-r--r-- | src/imgui/docs/BACKENDS.md | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/src/imgui/docs/BACKENDS.md b/src/imgui/docs/BACKENDS.md new file mode 100644 index 0000000..e5aa79b --- /dev/null +++ b/src/imgui/docs/BACKENDS.md @@ -0,0 +1,146 @@ +_(You may browse this at https://github.com/ocornut/imgui/blob/master/docs/BACKENDS.md or view this file with any Markdown viewer)_ + +## Dear ImGui: Backends + +**The backends/ folder contains backends for popular platforms/graphics API, which you can use in +your application or engine to easily integrate Dear ImGui.** Each backend is typically self-contained in a pair of files: imgui_impl_XXXX.cpp + imgui_impl_XXXX.h. + +- The 'Platform' backends are in charge of: mouse/keyboard/gamepad inputs, cursor shape, timing, and windowing.<BR> + e.g. Windows ([imgui_impl_win32.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_win32.cpp)), GLFW ([imgui_impl_glfw.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_glfw.cpp)), SDL2 ([imgui_impl_sdl2.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_sdl2.cpp)), etc. + +- The 'Renderer' backends are in charge of: creating atlas texture, and rendering imgui draw data.<BR> + e.g. DirectX11 ([imgui_impl_dx11.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_dx11.cpp)), OpenGL/WebGL ([imgui_impl_opengl3.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_opengl3.cpp)), Vulkan ([imgui_impl_vulkan.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_vulkan.cpp)), etc. + +- For some high-level frameworks, a single backend usually handles both 'Platform' and 'Renderer' parts.<BR> + e.g. Allegro 5 ([imgui_impl_allegro5.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_allegro5.cpp)). If you end up creating a custom backend for your engine, you may want to do the same. + +An application usually combines one Platform backend + one Renderer backend + main Dear ImGui sources. +For example, the [example_win32_directx11](https://github.com/ocornut/imgui/tree/master/examples/example_win32_directx11) application combines imgui_impl_win32.cpp + imgui_impl_dx11.cpp. There are 20+ examples in the [examples/](https://github.com/ocornut/imgui/blob/master/examples/) folder. See [EXAMPLES.MD](https://github.com/ocornut/imgui/blob/master/docs/EXAMPLES.md) for details. + +**Once Dear ImGui is setup and running, run and refer to `ImGui::ShowDemoWindow()` in imgui_demo.cpp for usage of the end-user API.** + + +### What are backends? + +Dear ImGui is highly portable and only requires a few things to run and render, typically: + + - Required: providing mouse/keyboard inputs (fed into the `ImGuiIO` structure). + - Required: uploading the font atlas texture into graphics memory. + - Required: rendering indexed textured triangles with a clipping rectangle. + + Extra features are opt-in, our backends try to support as many as possible: + + - Optional: custom texture binding support. + - Optional: clipboard support. + - Optional: gamepad support. + - Optional: mouse cursor shape support. + - Optional: IME support. + - Optional: multi-viewports support. + etc. + +This is essentially what each backend is doing + obligatory portability cruft. Using default backends ensure you can get all those features including the ones that would be harder to implement on your side (e.g. multi-viewports support). + +It is important to understand the difference between the core Dear ImGui library (files in the root folder) +and the backends which we are describing here (backends/ folder). + +- Some issues may only be backend or platform specific. +- You should be able to write backends for pretty much any platform and any 3D graphics API. + e.g. you can get creative and use software rendering or render remotely on a different machine. + + +### Integrating a backend + +See "Getting Started" section of [EXAMPLES.MD](https://github.com/ocornut/imgui/blob/master/docs/EXAMPLES.md) for more details. + + +### List of backends + +In the [backends/](https://github.com/ocornut/imgui/blob/master/backends) folder: + +List of Platforms Backends: + + imgui_impl_android.cpp ; Android native app API + imgui_impl_glfw.cpp ; GLFW (Windows, macOS, Linux, etc.) http://www.glfw.org/ + imgui_impl_osx.mm ; macOS native API (not as feature complete as glfw/sdl backends) + imgui_impl_sdl2.cpp ; SDL2 (Windows, macOS, Linux, iOS, Android) https://www.libsdl.org + imgui_impl_sdl3.cpp ; SDL3 (Windows, macOS, Linux, iOS, Android) https://www.libsdl.org (*EXPERIMENTAL UNTIL SDL3 IS RELEASED*) + imgui_impl_win32.cpp ; Win32 native API (Windows) + imgui_impl_glut.cpp ; GLUT/FreeGLUT (this is prehistoric software and absolutely not recommended today!) + +List of Renderer Backends: + + imgui_impl_dx9.cpp ; DirectX9 + imgui_impl_dx10.cpp ; DirectX10 + imgui_impl_dx11.cpp ; DirectX11 + imgui_impl_dx12.cpp ; DirectX12 + imgui_impl_metal.mm ; Metal (with ObjC) + imgui_impl_opengl2.cpp ; OpenGL 2 (legacy, fixed pipeline <- don't use with modern OpenGL context) + imgui_impl_opengl3.cpp ; OpenGL 3/4, OpenGL ES 2, OpenGL ES 3 (modern programmable pipeline) + imgui_impl_sdlrenderer2.cpp ; SDL_Renderer (optional component of SDL2 available from SDL 2.0.18+) + imgui_impl_sdlrenderer3.cpp ; SDL_Renderer (optional component of SDL3 available from SDL 3.0.0+) + imgui_impl_vulkan.cpp ; Vulkan + imgui_impl_wgpu.cpp ; WebGPU + +List of high-level Frameworks Backends (combining Platform + Renderer): + + imgui_impl_allegro5.cpp + +Emscripten is also supported! +The SDL+GL, GLFW+GL and SDL+WebGPU examples are all ready to build and run with Emscripten. + +### Backends for third-party frameworks, graphics API or other languages + +See https://github.com/ocornut/imgui/wiki/Bindings for the full list (e.g. Adventure Game Studio, Cinder, Cocos2d-x, Game Maker Studio2, Godot, LÖVE+LUA, Magnum, Monogame, Ogre, openFrameworks, OpenSceneGraph, SFML, Sokol, Unity, Unreal Engine and many others). + +### Recommended Backends + +If you are not sure which backend to use, the recommended platform/frameworks for portable applications: + +|Library |Website |Backend |Note | +|--------|--------|--------|-----| +| GLFW | https://github.com/glfw/glfw | imgui_impl_glfw.cpp | | +| SDL2 | https://www.libsdl.org | imgui_impl_sdl2.cpp | | +| Sokol | https://github.com/floooh/sokol | [util/sokol_imgui.h](https://github.com/floooh/sokol/blob/master/util/sokol_imgui.h) | Lower-level than GLFW/SDL | + + +### Using a custom engine? + +You will likely be tempted to start by rewrite your own backend using your own custom/high-level facilities...<BR> +Think twice! + +If you are new to Dear ImGui, first try using the existing backends as-is. +You will save lots of time integrating the library. +You can LATER decide to rewrite yourself a custom backend if you really need to. +In most situations, custom backends have fewer features and more bugs than the standard backends we provide. +If you want portability, you can use multiple backends and choose between them either at compile time +or at runtime. + +**Example A**: your engine is built over Windows + DirectX11 but you have your own high-level rendering +system layered over DirectX11.<BR> +Suggestion: try using imgui_impl_win32.cpp + imgui_impl_dx11.cpp first. +Once it works, if you really need it, you can replace the imgui_impl_dx11.cpp code with a +custom renderer using your own rendering functions, and keep using the standard Win32 code etc. + +**Example B**: your engine runs on Windows, Mac, Linux and uses DirectX11, Metal, and Vulkan respectively.<BR> +Suggestion: use multiple generic backends! +Once it works, if you really need it, you can replace parts of backends with your own abstractions. + +**Example C**: your engine runs on platforms we can't provide public backends for (e.g. PS4/PS5, Switch), +and you have high-level systems everywhere.<BR> +Suggestion: try using a non-portable backend first (e.g. win32 + underlying graphics API) to get +your desktop builds working first. This will get you running faster and get your acquainted with +how Dear ImGui works and is setup. You can then rewrite a custom backend using your own engine API... + +Generally: +It is unlikely you will add value to your project by creating your own backend. + +Also: +The [multi-viewports feature](https://github.com/ocornut/imgui/issues/1542) of the 'docking' branch allows +Dear ImGui windows to be seamlessly detached from the main application window. This is achieved using an +extra layer to the Platform and Renderer backends, which allows Dear ImGui to communicate platform-specific +requests such as: "create an additional OS window", "create a render context", "get the OS position of this +window" etc. See 'ImGuiPlatformIO' for details. +Supporting the multi-viewports feature correctly using 100% of your own abstractions is more difficult +than supporting single-viewport. +If you decide to use unmodified imgui_impl_XXXX.cpp files, you can automatically benefit from +improvements and fixes related to viewports and platform windows without extra work on your side. |