BACKENDS.md (8497B)
1 _(You may browse this at https://github.com/ocornut/imgui/blob/master/docs/BACKENDS.md or view this file with any Markdown viewer)_ 2 3 ## Dear ImGui: Backends 4 5 **The backends/ folder contains backends for popular platforms/graphics API, which you can use in 6 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. 7 8 - The 'Platform' backends are in charge of: mouse/keyboard/gamepad inputs, cursor shape, timing, windowing.<BR> 9 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_sdl.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_sdl.cpp)), etc. 10 11 - The 'Renderer' backends are in charge of: creating atlas texture, rendering imgui draw data.<BR> 12 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. 13 14 - For some high-level frameworks, a single backend usually handle both 'Platform' and 'Renderer' parts.<BR> 15 e.g. Allegro 5 ([imgui_impl_allegro5.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_allegro5.cpp)), Marmalade ([imgui_impl_marmalade.cpp](https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_marmalade.cpp)). If you end up creating a custom backend for your engine, you may want to do the same. 16 17 An application usually combines 1 Platform backend + 1 Renderer backend + main Dear ImGui sources. 18 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. 19 20 **Once Dear ImGui is setup and running, run and refer to `ImGui::ShowDemoWindow()` in imgui_demo.cpp for usage of the end-user API.** 21 22 23 ### What are backends 24 25 Dear ImGui is highly portable and only requires a few things to run and render, typically: 26 27 - Required: providing mouse/keyboard inputs (fed into the `ImGuiIO` structure). 28 - Required: uploading the font atlas texture into graphics memory. 29 - Required: rendering indexed textured triangles with a clipping rectangle. 30 31 Extra features are opt-in, our backends try to support as many as possible: 32 33 - Optional: custom texture binding support. 34 - Optional: clipboard support. 35 - Optional: gamepad support. 36 - Optional: mouse cursor shape support. 37 - Optional: IME support. 38 - Optional: multi-viewports support. 39 etc. 40 41 This is essentially what each backends are 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). 42 43 It is important to understand the difference between the core Dear ImGui library (files in the root folder) 44 and backends which we are describing here (backends/ folder). 45 46 - Some issues may only be backend or platform specific. 47 - You should be able to write backends for pretty much any platform and any 3D graphics API. 48 e.g. you can get creative and use software rendering or render remotely on a different machine. 49 50 51 ### Integrating a backend 52 53 See "Getting Started" section of [EXAMPLES.MD](https://github.com/ocornut/imgui/blob/master/docs/EXAMPLES.md) for more details. 54 55 56 ### List of backends 57 58 In the [backends/](https://github.com/ocornut/imgui/blob/master/backends) folder: 59 60 List of Platforms Backends: 61 62 imgui_impl_android.cpp ; Android native app API 63 imgui_impl_glfw.cpp ; GLFW (Windows, macOS, Linux, etc.) http://www.glfw.org/ 64 imgui_impl_osx.mm ; macOS native API (not as feature complete as glfw/sdl backends) 65 imgui_impl_sdl.cpp ; SDL2 (Windows, macOS, Linux, iOS, Android) https://www.libsdl.org 66 imgui_impl_win32.cpp ; Win32 native API (Windows) 67 imgui_impl_glut.cpp ; GLUT/FreeGLUT (this is prehistoric software and absolutely not recommended today!) 68 69 List of Renderer Backends: 70 71 imgui_impl_dx9.cpp ; DirectX9 72 imgui_impl_dx10.cpp ; DirectX10 73 imgui_impl_dx11.cpp ; DirectX11 74 imgui_impl_dx12.cpp ; DirectX12 75 imgui_impl_metal.mm ; Metal (with ObjC) 76 imgui_impl_opengl2.cpp ; OpenGL 2 (legacy, fixed pipeline <- don't use with modern OpenGL context) 77 imgui_impl_opengl3.cpp ; OpenGL 3/4, OpenGL ES 2, OpenGL ES 3 (modern programmable pipeline) 78 imgui_impl_vulkan.cpp ; Vulkan 79 imgui_impl_wgpu.cpp ; WebGPU 80 81 List of high-level Frameworks Backends (combining Platform + Renderer): 82 83 imgui_impl_allegro5.cpp 84 imgui_impl_marmalade.cpp 85 86 Emscripten is also supported. 87 The [example_emscripten_opengl3](https://github.com/ocornut/imgui/tree/master/examples/example_emscripten_opengl3) app uses imgui_impl_sdl.cpp + imgui_impl_opengl3.cpp, but other combos are possible. 88 89 ### Backends for third-party frameworks, graphics API or other languages 90 91 See https://github.com/ocornut/imgui/wiki/Bindings for the full list. 92 93 ### Recommended Backends 94 95 If you are not sure which backend to use, the recommended platform/frameworks for portable applications: 96 97 |Library |Website |Backend |Note | 98 |--------|--------|--------|-----| 99 | GLFW | https://github.com/glfw/glfw | imgui_impl_glfw.cpp | | 100 | SDL2 | https://www.libsdl.org | imgui_impl_sdl.cpp | | 101 | 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 | 102 103 104 ### Using a custom engine? 105 106 You will likely be tempted to start by rewrite your own backend using your own custom/high-level facilities...<BR> 107 Think twice! 108 109 If you are new to Dear ImGui, first try using the existing backends as-is. 110 You will save lots of time integrating the library. 111 You can LATER decide to rewrite yourself a custom backend if you really need to. 112 In most situations, custom backends have less features and more bugs than the standard backends we provide. 113 If you want portability, you can use multiple backends and choose between them either at compile time 114 or at runtime. 115 116 **Example A**: your engine is built over Windows + DirectX11 but you have your own high-level rendering 117 system layered over DirectX11.<BR> 118 Suggestion: try using imgui_impl_win32.cpp + imgui_impl_dx11.cpp first. 119 Once it works, if you really need it you can replace the imgui_impl_dx11.cpp code with a 120 custom renderer using your own rendering functions, and keep using the standard Win32 code etc. 121 122 **Example B**: your engine runs on Windows, Mac, Linux and uses DirectX11, Metal, Vulkan respectively.<BR> 123 Suggestion: use multiple generic backends! 124 Once it works, if you really need it you can replace parts of backends with your own abstractions. 125 126 **Example C**: your engine runs on platforms we can't provide public backends for (e.g. PS4/PS5, Switch), 127 and you have high-level systems everywhere.<BR> 128 Suggestion: try using a non-portable backend first (e.g. win32 + underlying graphics API) to get 129 your desktop builds working first. This will get you running faster and get your acquainted with 130 how Dear ImGui works and is setup. You can then rewrite a custom backend using your own engine API. 131 132 Also: 133 The [multi-viewports feature](https://github.com/ocornut/imgui/issues/1542) of the 'docking' branch allows 134 Dear ImGui windows to be seamlessly detached from the main application window. This is achieved using an 135 extra layer to the Platform and Renderer backends, which allows Dear ImGui to communicate platform-specific 136 requests such as: "create an additional OS window", "create a render context", "get the OS position of this 137 window" etc. See 'ImGuiPlatformIO' for details. 138 Supporting the multi-viewports feature correctly using 100% of your own abstractions is more difficult 139 than supporting single-viewport. 140 If you decide to use unmodified imgui_impl_XXXX.cpp files, you can automatically benefit from 141 improvements and fixes related to viewports and platform windows without extra work on your side.