text: // ImGui - standalone example application for GLFW + OpenGL2, using legacy fixed pipeline
  // If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
  // (GLFW is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
  
  // **DO NOT USE THIS CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)**
  // **Prefer using the code in the opengl3_example/ folder**
  // See imgui_impl_glfw.cpp for details.
  
  #include "imgui.h"
  #include "imgui_impl_glfw_gl2.h"
  #include <stdio.h>
  #include <GLFW/glfw3.h>
  
  static void glfw_error_callback(int error, const char* description)
  {
      fprintf(stderr, "Error %d: %s\n", error, description);
  }
  
  int main(int, char**)
  {
      // Setup window
      glfwSetErrorCallback(glfw_error_callback);
      if (!glfwInit())
          return 1;
      GLFWwindow* window = glfwCreateWindow(1280, 720, "ImGui GLFW+OpenGL2 example", NULL, NULL);
      glfwMakeContextCurrent(window);
      glfwSwapInterval(1); // Enable vsync
  
      // Setup Dear ImGui binding
      IMGUI_CHECKVERSION();
      ImGui::CreateContext();
      ImGuiIO& io = ImGui::GetIO(); (void)io;
      //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
      ImGui_ImplGlfwGL2_Init(window, true);
  
      // Setup style
      ImGui::StyleColorsDark();
      //ImGui::StyleColorsClassic();
  
      // 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 'misc/fonts/README.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);
  
      bool show_demo_window = true;
      bool show_another_window = false;
      ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
  
      // Main loop
      while (!glfwWindowShouldClose(window))
      {
          // 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.
          glfwPollEvents();
          ImGui_ImplGlfwGL2_NewFrame();
  
          // 1. Show a simple window.
          // Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets automatically appears in a window called "Debug".
          {
              static float f = 0.0f;
              static int counter = 0;
              ImGui::Text("Hello, world!");                           // Display some text (you can use a format string too)
              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
  
              ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our windows open/close state
              ImGui::Checkbox("Another Window", &show_another_window);
  
              if (ImGui::Button("Button"))                            // Buttons return true when clicked (NB: 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);
          }
  
          // 2. Show another simple window. In most cases you will use an explicit Begin/End pair to name your windows.
          if (show_another_window)
          {
              ImGui::Begin("Another Window", &show_another_window);
              ImGui::Text("Hello from another window!");
              if (ImGui::Button("Close Me"))
                  show_another_window = false;
              ImGui::End();
          }
  
          // 3. Show the ImGui demo window. Most of the sample code is in ImGui::ShowDemoWindow(). Read its code to learn more about Dear ImGui!
          if (show_demo_window)
          {
              ImGui::SetNextWindowPos(ImVec2(650, 20), ImGuiCond_FirstUseEver); // Normally user code doesn't need/want to call this because positions are saved in .ini file anyway. Here we just want to make the demo initial state a bit more friendly!
              ImGui::ShowDemoWindow(&show_demo_window);
          }
  
          // Rendering
          int display_w, display_h;
          glfwGetFramebufferSize(window, &display_w, &display_h);
          glViewport(0, 0, display_w, display_h);
          glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
          glClear(GL_COLOR_BUFFER_BIT);
          //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound, but prefer using the GL3+ code.
          ImGui::Render();
          ImGui_ImplGlfwGL2_RenderDrawData(ImGui::GetDrawData());
          glfwSwapBuffers(window);
      }
  
      // Cleanup
      ImGui_ImplGlfwGL2_Shutdown();
      ImGui::DestroyContext();
  
      glfwDestroyWindow(window);
      glfwTerminate();
  
      return 0;
  }
  