main.cpp

// Dear ImGui: standalone example application for SDL2 + OpenGL
// (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan/Metal graphics context creation, etc.)
// 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

#include "imgui.h"
#include "imgui_impl_opengl3.h"
#include "imgui_impl_sdl2.h"
#include <SDL.h>
#include <iostream>
#include <stdio.h>
#include <string>
#include <thread>
#if defined(IMGUI_IMPL_OPENGL_ES2)
#include <SDL_opengles2.h>
#else
#include <SDL_opengl.h>
#endif

// This example can also compile and run with Emscripten! See 'Makefile.emscripten' for details.
#ifdef __EMSCRIPTEN__
#include <emscripten/atomic.h>
#include <emscripten/threading.h>

#include "emscripten/emscripten_mainloop_stub.h"
#endif

// Main code
int main(int, char **) {
#ifdef __EMSCRIPTEN_PTHREADS__
	std::cout << "__EMSCRIPTEN_PTHREADS__" << std::endl;
#endif
#ifdef __EMSCRIPTEN__
	std::cout << "emscripten_has_threading_support=" << emscripten_has_threading_support() << std::endl;
	std::cout << "emscripten_num_logical_cores=" << emscripten_num_logical_cores() << std::endl;
#endif
	// Setup SDL
	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0) {
		printf("Error: %s\n", SDL_GetError());
		return -1;
	}

	// Decide GL+GLSL versions
#if defined(IMGUI_IMPL_OPENGL_ES2)
	// GL ES 2.0 + GLSL 100
	const char *glsl_version = "#version 100";
	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);
#elif defined(__APPLE__)
	// GL 3.2 Core + GLSL 150
	const char *glsl_version = "#version 150";
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);// Always required on Mac
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
#else
	// GL 3.0 + GLSL 130
	const char *glsl_version = "#version 130";
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
#endif

	// From 2.0.18: Enable native IME.
#ifdef SDL_HINT_IME_SHOW_UI
	SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");
#endif

	// 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_WindowFlags window_flags = (SDL_WindowFlags) (SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
	SDL_Window *window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
	SDL_GLContext gl_context = SDL_GL_CreateContext(window);
	SDL_GL_MakeCurrent(window, gl_context);
	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

	// Setup Dear ImGui style
	ImGui::StyleColorsDark();
	//ImGui::StyleColorsLight();

	// Setup Platform/Renderer backends
	ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
	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.
	// - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
	// - 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 \\ !
	// - Our Emscripten build process allows embedding fonts to be accessible at runtime from the "fonts/" folder. See Makefile.emscripten for details.
	//io.Fonts->AddFontDefault();
	//io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
	//ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
	//IM_ASSERT(font != NULL);

	// Our state
	bool show_demo_window = true;
	bool show_another_window = false;
	ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

	static std::unique_ptr<std::thread> thread;

	// Main loop
	bool done = false;
#ifdef __EMSCRIPTEN__
	// 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;
	EMSCRIPTEN_MAINLOOP_BEGIN
#else
	while (!done)
#endif
	{

		// 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);
			if (event.type == SDL_QUIT)
				done = true;
			if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
				done = true;
		}

		// 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 create 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++;
				if (!thread) {
					std::cout << "starting thread..." << std::endl;
					thread = std::make_unique<std::thread>(std::thread([]() {
					}));
				}
			}
			ImGui::SameLine();
			ImGui::Text("counter = %d", counter);

			ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.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!");
			char buf[128];
			SDL_StartTextInput();
			if (ImGui::InputText("Hello", reinterpret_cast<char *>(&buf), 128)) {
				std::string input{buf};
				std::cout << input << std::endl;
			}
			if (ImGui::Button("Close Me"))
				show_another_window = false;
			ImGui::End();
		}

		// Rendering
		ImGui::Render();
		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(window);
	}
#ifdef __EMSCRIPTEN__
	EMSCRIPTEN_MAINLOOP_END;
#endif

	if (thread)
		thread->join();

	// Cleanup
	ImGui_ImplOpenGL3_Shutdown();
	ImGui_ImplSDL2_Shutdown();
	ImGui::DestroyContext();

	SDL_GL_DeleteContext(gl_context);
	SDL_DestroyWindow(window);
	SDL_Quit();

	return 0;
}