cimgui/backend_test/example_sdl_opengl3/main.c

#define CIMGUI_DEFINE_ENUMS_AND_STRUCTS
#include "cimgui.h"
#include "cimgui_impl.h"
#include <stdio.h>
#define SDL_MAIN_HANDLED
#include <SDL.h>
#ifdef _MSC_VER
#include <windows.h>
#endif
#include <GL/gl.h>
#include <GL/glu.h>

#ifdef _WIN32
#include <windows.h>        // SetProcessDPIAware()
#endif

#ifdef IMGUI_HAS_IMSTR
#define igBegin igBegin_Str
#define igSliderFloat igSliderFloat_Str
#define igCheckbox igCheckbox_Str
#define igColorEdit3 igColorEdit3_Str
#define igButton igButton_Str
#endif

#define igGetIO igGetIO_Nil

SDL_Window *window = NULL;

int main(int argc, char* argv[])
{
#ifdef _WIN32
    SetProcessDPIAware();
#endif

  if (SDL_Init(SDL_INIT_VIDEO) < 0) {
    SDL_Log("failed to init: %s", SDL_GetError());
    return -1;
  }
 
  // Decide GL+GLSL versions
#if __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

  // and prepare OpenGL stuff
  SDL_SetHint(SDL_HINT_RENDER_DRIVER, "opengl");
  SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
  SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
  SDL_DisplayMode current;
  SDL_GetCurrentDisplayMode(0, &current);
  float main_scale = ImGui_ImplSDL2_GetContentScaleForDisplay(0);
  SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
  window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, (int)(1280 * main_scale), (int)(720 * main_scale), window_flags);
 
  if (window == NULL) {
    SDL_Log("Failed to create window: %s", SDL_GetError());
    return -1;
  }

  SDL_GLContext gl_context = SDL_GL_CreateContext(window);
  SDL_GL_SetSwapInterval(1);  // enable vsync


  // check opengl version sdl uses
  SDL_Log("opengl version: %s", (char*)glGetString(GL_VERSION));

  // setup imgui
  igCreateContext(NULL);
  
  //set docking
  ImGuiIO* ioptr = igGetIO();
  ioptr->ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
  //ioptr->ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
#ifdef IMGUI_HAS_DOCK
  ioptr->ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
  ioptr->ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
#endif
  
    // Setup scaling
    ImGuiStyle* style = igGetStyle();
    ImGuiStyle_ScaleAllSizes(style, main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
    style->FontScaleDpi = main_scale;        // Set initial font scale. (using io.ConfigDpiScaleFonts=true makes this unnecessary. We leave both here for documentation purpose)
    ioptr->ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
    ioptr->ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.


  ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
  ImGui_ImplOpenGL3_Init(glsl_version);

  igStyleColorsDark(NULL);
  //ImFontAtlas_AddFontDefault(io.Fonts, NULL);


  bool showDemoWindow = true;
  bool showAnotherWindow = false;
  ImVec4 clearColor;
  clearColor.x = 0.45f;
  clearColor.y = 0.55f;
  clearColor.z = 0.60f;
  clearColor.w = 1.00f;

  bool quit = false;
  while (!quit)
  {
    SDL_Event e;

    // we need to call SDL_PollEvent to let window rendered, otherwise
    // no window will be shown
    while (SDL_PollEvent(&e) != 0)
    {
      ImGui_ImplSDL2_ProcessEvent(&e);
      if (e.type == SDL_QUIT)
        quit = true;
      if (e.type == SDL_WINDOWEVENT && e.window.event == SDL_WINDOWEVENT_CLOSE && e.window.windowID == SDL_GetWindowID(window))
        quit = true;
    }
    
    // start imgui frame
    ImGui_ImplOpenGL3_NewFrame();
    ImGui_ImplSDL2_NewFrame();
    igNewFrame();

    if (showDemoWindow)
      igShowDemoWindow(&showDemoWindow);

    // show a simple window that we created ourselves.
    {
      static float f = 0.0f;
      static int counter = 0;

      igBegin("Hello, world!", NULL, 0);
      igText("This is some useful text");
      igCheckbox("Demo window", &showDemoWindow);
      igCheckbox("Another window", &showAnotherWindow);

      igSliderFloat("Float", &f, 0.0f, 1.0f, "%.3f", 0);
      igColorEdit3("clear color", (float*)&clearColor, 0);

      ImVec2 buttonSize;
      buttonSize.x = 0;
      buttonSize.y = 0;
      if (igButton("Button", buttonSize))
        counter++;
      igSameLine(0.0f, -1.0f);
      igText("counter = %d", counter);

      igText("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / igGetIO()->Framerate, igGetIO()->Framerate);
      igEnd();
    }

    if (showAnotherWindow)
    {
      igBegin("imgui Another Window", &showAnotherWindow, 0);
      igText("Hello from imgui");
      ImVec2 buttonSize;
      buttonSize.x = 0; buttonSize.y = 0;
      if (igButton("Close me", buttonSize))
      {
        showAnotherWindow = false;
      }
      igEnd();
    }

    // render
    igRender();
    SDL_GL_MakeCurrent(window, gl_context);
    glViewport(0, 0, (int)ioptr->DisplaySize.x, (int)ioptr->DisplaySize.y);
    glClearColor(clearColor.x, clearColor.y, clearColor.z, clearColor.w);
    glClear(GL_COLOR_BUFFER_BIT);
    ImGui_ImplOpenGL3_RenderDrawData(igGetDrawData());
#ifdef IMGUI_HAS_DOCK
	if (ioptr->ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
        {
            SDL_Window* backup_current_window = SDL_GL_GetCurrentWindow();
            SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
            igUpdatePlatformWindows();
            igRenderPlatformWindowsDefault(NULL,NULL);
            SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
        }
#endif
    SDL_GL_SwapWindow(window);
  }

  // clean up
  ImGui_ImplOpenGL3_Shutdown();
  ImGui_ImplSDL2_Shutdown();
  igDestroyContext(NULL);

  SDL_GL_DeleteContext(gl_context);
  if (window != NULL)
  {
    SDL_DestroyWindow(window);
    window = NULL;
  }
  SDL_Quit();

  return 0;
}