text: // dear imgui: standalone example application for SDL2 + OpenGL
  // If you are new to dear imgui, see examples/README.txt and documentation at the top of imgui.cpp.
  // (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan/Metal graphics context creation, etc.)
  // (GL3W is a helper library to access OpenGL functions since there is no standard header to access modern OpenGL functions easily. Alternatives are GLEW, Glad, etc.)
  
  #include "imgui.h"
  #include "imgui_impl_sdl.h"
  #include "imgui_impl_opengl3.h"
  #include <stdio.h>
  #include <SDL.h>
  
  // About Desktop OpenGL function loaders:
  //  Modern desktop OpenGL doesn't have a standard portable header file to load OpenGL function pointers.
  //  Helper libraries are often used for this purpose! Here we are supporting a few common ones (gl3w, glew, glad).
  //  You may use another loader/header of your choice (glext, glLoadGen, etc.), or chose to manually implement your own.
  
  #if defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
  #include <GL/glew.h>    // Initialize with glewInit()
  #endif
  
  // Main code
  int main(int, char**)
  {
      // Setup SDL
      // (Some versions of SDL before <2.0.10 appears to have performance/stalling issues on a minority of Windows systems,
      // depending on whether SDL_INIT_GAMECONTROLLER is enabled or disabled.. updating to latest version of SDL is recommended!)
      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
  
      // GL 3.0 + GLSL 130
      const char* glsl_version = "#version 450";
      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, 4);
      SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 5);
  
      // 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
  
      // Initialize OpenGL loader
  #if defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
      bool err = glewInit() != GLEW_OK;
  #endif
      if (err)
      {
          fprintf(stderr, "Failed to initialize OpenGL loader!\n");
          return 1;
      }
  
      // 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::StyleColorsClassic();
  
      // Setup Platform/Renderer bindings
      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.
      // - Read 'docs/FONTS.txt' 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 \\ !
      //io.Fonts->AddFontDefault();
      //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
      //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
      //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
      //io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
      //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);
  
      // Main loop
      bool done = false;
      while (!done)
      {
          // 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.
          // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
          // 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(window);
          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();
          glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
          glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
          glClear(GL_COLOR_BUFFER_BIT);
          ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
          SDL_GL_SwapWindow(window);
      }
  
      // Cleanup
      ImGui_ImplOpenGL3_Shutdown();
      ImGui_ImplSDL2_Shutdown();
      ImGui::DestroyContext();
  
      SDL_GL_DeleteContext(gl_context);
      SDL_DestroyWindow(window);
      SDL_Quit();
  
      return 0;
  }
  