SDL3 backend support :)

[picosaur]

It has a lot of new features...
https://wiki.libsdl.org/SDL3/NewFeatures
so it will be nice to have hello_imgui ready for.

[pthom]

Hello,

Support for SDL3 is not currently being worked on, as I’m juggling multiple projects with limited time.

For information here are some more details if someone want to contribute on this.

Adding a new platform backend requires significant care and effort because Hello ImGui needs to remain compatible with various combinations of:

1. Platform backends: SDL, GLFW
2. Rendering backends: OpenGL, Metal, DirectX (11/12), Vulkan
3. Operating systems: Linux, macOS, Windows, iOS, Android, and Emscripten

All these combinations must be manually tested across CI pipelines.

Additionally, introducing a new backend would need to maintain core features such as:

• Consistent window size and position handling across platforms
• Support for fullscreen apps and monitor selection
• Proper high-DPI handling
• Application icon configuration

Areas Requiring Changes for SDL3 Support:

C++

• src/hello_imgui/internal/backend_impls/runner_sdl2.[h-cpp]: Main implementation
• src/hello_imgui/internal/backend_impls/backend_window_helper/sdl_window_helper.[h-cpp]: Window creation and fullscreen handling
• src/hello_imgui/internal/backend_impls/opengl_setup_helper/opengl_setup_sdl.[h-cpp]: OpenGL-specific setup
• src/hello_imgui/internal/backend_impls/runner_sdl_emscripten.h: Emscripten-related handling
• src/hello_imgui/internal/backend_impls/win32_dpi_awareness: High-DPI handling

CMake

• hello_imgui_cmake/hello_imgui_build_lib.cmake: Central location for all HelloImGui's CMake options

If/when SDL3 support is considered, careful planning and execution will be necessary to ensure:

• compatibility and feature parity
• testing and maintenance accross all combination of OS / platform backend / rendering backend

Currently Supported combinations of OS / Platform Backend / Rendering backend

There are currently 21 supported combinations (which is a lot to maintain, and test whether manually and in CI).
Adding support for SDL3 would mechanically increase this number by a factor of approx 1.5.

Operating System	Platform Backend	Rendering Backend
Linux	GLFW3	OpenGL
Linux	SDL2	OpenGL
Linux	GLFW3	Vulkan
Linux	SDL2	Vulkan
macOS	GLFW3	OpenGL
macOS	SDL2	OpenGL
macOS	GLFW3	Metal
macOS	SDL2	Metal
Windows	GLFW3	OpenGL
Windows	SDL2	OpenGL
Windows	GLFW3	Vulkan
Windows	SDL2	Vulkan
Windows	GLFW3	DirectX 11
Windows	SDL2	DirectX 11
Windows	GLFW3	DirectX 12
Windows	SDL2	DirectX 12
iOS	SDL2	OpenGL
iOS	SDL2	Metal
Android	SDL2	OpenGL
Android	SDL2	Vulkan
Emscripten	SDL2	OpenGL (WebGL)