source: opengl-game/imgui_example.cpp@ c1ca5b5

// ImGui - standalone example application for GLFW + OpenGL 3, using programmable 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.)

#include "IMGUI/imgui.h"
#include "imgui_impl_glfw_gl3.h"
#include <stdio.h>

#include <GL/glew.h>
#include <GLFW/glfw3.h>

static void glfw_error_callback(int error, const char* description)
{
   fprintf(stderr, "Error %d: %s\n", error, description);
}

int mainimgui(int, char**)
{
   // Setup window
   glfwSetErrorCallback(glfw_error_callback);
   if (!glfwInit())
      return 1;
   glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
   glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
   glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#if __APPLE__
   glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
   GLFWwindow* window = glfwCreateWindow(1280, 720, "ImGui GLFW+OpenGL3 example", NULL, NULL);
   glfwMakeContextCurrent(window);
   glfwSwapInterval(1); // Enable vsync

   glewExperimental = GL_TRUE;
   glewInit();

   // Setup Dear ImGui binding
   IMGUI_CHECKVERSION();
   ImGui::CreateContext();
   ImGuiIO& io = ImGui::GetIO(); (void)io;
   //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
   //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;   // Enable Gamepad Controls
   ImGui_ImplGlfwGL3_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_ImplGlfwGL3_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);
      ImGui::Render();
      ImGui_ImplGlfwGL3_RenderDrawData(ImGui::GetDrawData());
      glfwSwapBuffers(window);
   }

   // Cleanup
   ImGui_ImplGlfwGL3_Shutdown();
   ImGui::DestroyContext();

   glfwDestroyWindow(window);
   glfwTerminate();

   return 0;
}