imgui/examples/sdl_opengl3_example/main.cpp

// ImGui - standalone example application for SDL2 + OpenGL

#include <imgui.h>
#include "imgui_impl_sdl_gl3.h"
#include <stdio.h>
#include <GL/gl3w.h>
#include <SDL.h>

int main(int, char**)
{
    // Setup SDL
	if (SDL_Init(SDL_INIT_EVERYTHING) != 0)
	{
        printf("Error: %s\n", SDL_GetError());
        return -1;
	}

    // Setup window
	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
	SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
	SDL_DisplayMode current;
	SDL_GetCurrentDisplayMode(0, &current);
	SDL_Window *window = SDL_CreateWindow("ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
	SDL_GLContext glcontext = SDL_GL_CreateContext(window);
    gl3wInit();

    // Setup ImGui binding
    ImGui_ImplSdlGL3_Init(window);

    // Load Fonts
    // (see extra_fonts/README.txt for more details)
    //ImGuiIO& io = ImGui::GetIO();
    //io.Fonts->AddFontDefault();
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/Cousine-Regular.ttf", 15.0f);
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/DroidSans.ttf", 16.0f);
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/ProggyClean.ttf", 13.0f);
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/ProggyTiny.ttf", 10.0f);
    //io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());

    // Merge glyphs from multiple fonts into one (e.g. combine default font with another with Chinese glyphs, or add icons)
    //ImWchar icons_ranges[] = { 0xf000, 0xf3ff, 0 };
    //ImFontConfig icons_config; icons_config.MergeMode = true; icons_config.PixelSnapH = true;
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/DroidSans.ttf", 18.0f);
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/fontawesome-webfont.ttf", 18.0f, &icons_config, icons_ranges);

    bool show_test_window = true;
    bool show_another_window = false;
    ImVec4 clear_color = ImColor(114, 144, 154);

    // Main loop
	bool done = false;
    while (!done)
    {
        SDL_Event event;
        while (SDL_PollEvent(&event))
        {
            ImGui_ImplSdlGL3_ProcessEvent(&event);
            if (event.type == SDL_QUIT)
                done = true;
        }
        ImGui_ImplSdlGL3_NewFrame();

        // 1. Show a simple window
        // Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets appears in a window automatically called "Debug"
        {
            static float f = 0.0f;
            ImGui::Text("Hello, world!");
            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
            ImGui::ColorEdit3("clear color", (float*)&clear_color);
            if (ImGui::Button("Test Window")) show_test_window ^= 1;
            if (ImGui::Button("Another Window")) show_another_window ^= 1;
            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
        }

        // 2. Show another simple window, this time using an explicit Begin/End pair
        if (show_another_window)
        {
            ImGui::SetNextWindowSize(ImVec2(200,100), ImGuiSetCond_FirstUseEver);
            ImGui::Begin("Another Window", &show_another_window);
            ImGui::Text("Hello");
            ImGui::End();
        }

        // 3. Show the ImGui test window. Most of the sample code is in ImGui::ShowTestWindow()
        if (show_test_window)
        {
            ImGui::SetNextWindowPos(ImVec2(650, 20), ImGuiSetCond_FirstUseEver);
            ImGui::ShowTestWindow(&show_test_window);
        }

        // Rendering
        glViewport(0, 0, (int)ImGui::GetIO().DisplaySize.x, (int)ImGui::GetIO().DisplaySize.y);
        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
        glClear(GL_COLOR_BUFFER_BIT);
        ImGui::Render();
        SDL_GL_SwapWindow(window);
    }

    // Cleanup
    ImGui_ImplSdlGL3_Shutdown();
    SDL_GL_DeleteContext(glcontext);  
	SDL_DestroyWindow(window);
	SDL_Quit();

    return 0;
}