mirror of https://github.com/ocornut/imgui
You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
39 lines
2.7 KiB
C++
39 lines
2.7 KiB
C++
// What does this file solves?
|
|
// - Since Dear ImGui 1.00 we took pride that most of our examples applications had their entire
|
|
// main-loop inside the main() function. That's because:
|
|
// - It makes the examples easier to read, keeping the code sequential.
|
|
// - It permit the use of local variables, making it easier to try things and perform quick
|
|
// changes when someone needs to quickly test something (vs having to structure the example
|
|
// in order to pass data around). This is very important because people use those examples
|
|
// to craft easy-to-past repro when they want to discuss features or report issues.
|
|
// - It conveys at a glance that this is a no-BS framework, it won't take your main loop away from you.
|
|
// - It is generally nice and elegant.
|
|
// - However, comes Emscripten... it is a wonderful and magical tech but it requires a "main loop" function.
|
|
// - Only some of our examples would run on Emscripten. Typically the ones rendering with GL or WGPU ones.
|
|
// - I tried to refactor those examples but felt it was problematic that other examples didn't follow the
|
|
// same layout. Why would the SDL+GL example be structured one way and the SGL+DX11 be structured differently?
|
|
// Especially as we are trying hard to convey that using a Dear ImGui backend in an *existing application*
|
|
// should requires only a few dozens lines of code, and this should be consistent and symmetrical for all backends.
|
|
// - So the next logical step was to refactor all examples to follow that layout of using a "main loop" function.
|
|
// This worked, but it made us lose all the nice things we had...
|
|
|
|
// Since only about 4 examples really need to run with Emscripten, here's our solution:
|
|
// - Use some weird macros and capturing lambda to turn a loop in main() into a function.
|
|
// - Hide all that crap in this file so it doesn't make our examples unusually ugly.
|
|
// As a stance and principle of Dear ImGui development we don't use C++ headers and we don't
|
|
// want to suggest to the newcomer that we would ever use C++ headers as this would affect
|
|
// the initial judgment of many of our target audience.
|
|
// - Technique is based on this idea: https://github.com/ocornut/imgui/pull/2492/
|
|
// - The do { } while (0) is to allow our code calling continue in the main loop.
|
|
#ifdef __EMSCRIPTEN__
|
|
#include <emscripten.h>
|
|
#include <functional>
|
|
static std::function<void()> MainLoopForEmscriptenP;
|
|
static void MainLoopForEmscripten() { MainLoopForEmscriptenP(); }
|
|
#define EMSCRIPTEN_MAINLOOP_BEGIN MainLoopForEmscriptenP = [&]() { do
|
|
#define EMSCRIPTEN_MAINLOOP_END while (0); }; emscripten_set_main_loop(MainLoopForEmscripten, 0, true)
|
|
#else
|
|
#define EMSCRIPTEN_MAINLOOP_BEGIN
|
|
#define EMSCRIPTEN_MAINLOOP_END
|
|
#endif
|