// Dear ImGui: standalone example application for Emscripten, using SDL2 + OpenGL3 // (Emscripten is a C++-to-javascript compiler, used to publish executables for the web. See https://emscripten.org/) // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp. // Read online: https://github.com/ocornut/imgui/tree/master/docs // This is mostly the same code as the SDL2 + OpenGL3 example, simply with the modifications needed to run on Emscripten. // It is possible to combine both code into a single source file that will compile properly on Desktop and using Emscripten. // See https://github.com/ocornut/imgui/pull/2492 as an example on how to do just that. #include "imgui.h" #include "imgui_impl_sdl.h" #include "imgui_impl_opengl3.h" #include <stdio.h> #include <emscripten.h> #include <SDL.h> #include <SDL_opengles2.h> // Emscripten requires to have full control over the main loop. We're going to store our SDL book-keeping variables globally. // Having a single function that acts as a loop prevents us to store state in the stack of said function. So we need some location for this. SDL_Window* g_Window = NULL; SDL_GLContext g_GLContext = NULL; // For clarity, our main loop code is declared at the end. static void main_loop(void*); int main(int, char**) { // Setup SDL if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0) { printf("Error: %s\n", SDL_GetError()); return -1; } // For the browser using Emscripten, we are going to use WebGL1 with GL ES2. See the Makefile. for requirement details. // It is very likely the generated file won't work in many browsers. Firefox is the only sure bet, but I have successfully // run this code on Chrome for Android for example. const char* glsl_version = "#version 100"; //const char* glsl_version = "#version 300 es"; SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0); SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES); SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2); SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0); // Create window with graphics context SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1); SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24); SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8); SDL_DisplayMode current; SDL_GetCurrentDisplayMode(0, ¤t); SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI); g_Window = SDL_CreateWindow("Dear ImGui Emscripten example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags); g_GLContext = SDL_GL_CreateContext(g_Window); if (!g_GLContext) { fprintf(stderr, "Failed to initialize WebGL context!\n"); return 1; } SDL_GL_SetSwapInterval(1); // Enable vsync // Setup Dear ImGui context IMGUI_CHECKVERSION(); ImGui::CreateContext(); ImGuiIO& io = ImGui::GetIO(); (void)io; //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls // For an Emscripten build we are disabling file-system access, so let's not attempt to do a fopen() of the imgui.ini file. // You may manually call LoadIniSettingsFromMemory() to load settings from your own storage. io.IniFilename = NULL; // Setup Dear ImGui style ImGui::StyleColorsDark(); //ImGui::StyleColorsLight(); // Setup Platform/Renderer backends ImGui_ImplSDL2_InitForOpenGL(g_Window, g_GLContext); ImGui_ImplOpenGL3_Init(glsl_version); // Load Fonts // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them. // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple. // - If the file cannot be loaded, the function will return NULL. Please handle those errors in your application (e.g. use an assertion, or display an error and quit). // - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call. // - Read 'docs/FONTS.md' for more instructions and details. // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ ! // - Emscripten allows preloading a file or folder to be accessible at runtime. See Makefile for details. //io.Fonts->AddFontDefault(); #ifndef IMGUI_DISABLE_FILE_FUNCTIONS io.Fonts->AddFontFromFileTTF("fonts/Roboto-Medium.ttf", 16.0f); //io.Fonts->AddFontFromFileTTF("fonts/Cousine-Regular.ttf", 15.0f); //io.Fonts->AddFontFromFileTTF("fonts/DroidSans.ttf", 16.0f); //io.Fonts->AddFontFromFileTTF("fonts/ProggyTiny.ttf", 10.0f); //ImFont* font = io.Fonts->AddFontFromFileTTF("fonts/ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese()); //IM_ASSERT(font != NULL); #endif // This function call won't return, and will engage in an infinite loop, processing events from the browser, and dispatching them. emscripten_set_main_loop_arg(main_loop, NULL, 0, true); } static void main_loop(void* arg) { ImGuiIO& io = ImGui::GetIO(); IM_UNUSED(arg); // We can pass this argument as the second parameter of emscripten_set_main_loop_arg(), but we don't use that. // Our state (make them static = more or less global) as a convenience to keep the example terse. static bool show_demo_window = true; static bool show_another_window = false; static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f); // Poll and handle events (inputs, window resize, etc.) // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs. // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data. // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data. // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags. SDL_Event event; while (SDL_PollEvent(&event)) { ImGui_ImplSDL2_ProcessEvent(&event); // Capture events here, based on io.WantCaptureMouse and io.WantCaptureKeyboard } // Start the Dear ImGui frame ImGui_ImplOpenGL3_NewFrame(); ImGui_ImplSDL2_NewFrame(); ImGui::NewFrame(); // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!). if (show_demo_window) ImGui::ShowDemoWindow(&show_demo_window); // 2. Show a simple window that we create ourselves. We use a Begin/End pair to created a named window. { static float f = 0.0f; static int counter = 0; ImGui::Begin("Hello, world!"); // Create a window called "Hello, world!" and append into it. ImGui::Text("This is some useful text."); // Display some text (you can use a format strings too) ImGui::Checkbox("Demo Window", &show_demo_window); // Edit bools storing our window open/close state ImGui::Checkbox("Another Window", &show_another_window); ImGui::SliderFloat("float", &f, 0.0f, 1.0f); // Edit 1 float using a slider from 0.0f to 1.0f ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color if (ImGui::Button("Button")) // Buttons return true when clicked (most widgets return true when edited/activated) counter++; ImGui::SameLine(); ImGui::Text("counter = %d", counter); ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate); ImGui::End(); } // 3. Show another simple window. if (show_another_window) { ImGui::Begin("Another Window", &show_another_window); // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked) ImGui::Text("Hello from another window!"); if (ImGui::Button("Close Me")) show_another_window = false; ImGui::End(); } // Rendering ImGui::Render(); SDL_GL_MakeCurrent(g_Window, g_GLContext); glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y); glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w); glClear(GL_COLOR_BUFFER_BIT); ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData()); SDL_GL_SwapWindow(g_Window); }