329 lines
9.8 KiB
C++
329 lines
9.8 KiB
C++
/* xo-imgui/example/ex1/imgui_ex1.cpp
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*
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* author: Roland Conybeare, Aug 2025
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*/
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#include <SDL.h>
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#include <GL/glew.h>
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#include "SDL_events.h"
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#include "imgui.h"
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#include "backends/imgui_impl_sdl2.h"
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#include "backends/imgui_impl_opengl3.h"
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//#include <GLFW/glfw3.h>
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#ifdef NOPE
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#include <SDL_opengl.h>
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#endif
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#include <iostream>
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#include <unistd.h>
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int main(int, char **)
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{
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using namespace std;
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std::cout << "Hello, world!" << std::endl;
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SDL_SetHint(SDL_HINT_VIDEO_X11_FORCE_EGL, "0");
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SDL_Init(SDL_INIT_VIDEO);
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SDL_version compiled;
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SDL_VERSION(&compiled);
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std::cerr << "SDL version: "
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<< (int)compiled.major
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<< "." << (int)compiled.minor
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<< "." << (int)compiled.patch
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<< std::endl;
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SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
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SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
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SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK,
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SDL_GL_CONTEXT_PROFILE_CORE);
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SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
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#if 0
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SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS,
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SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
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#endif
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std::cerr << "SDL video driver: " << SDL_GetCurrentVideoDriver() << std::endl;
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SDL_Window * window = SDL_CreateWindow("imgui + sdl2 + opengl",
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SDL_WINDOWPOS_CENTERED,
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SDL_WINDOWPOS_CENTERED,
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1280,
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720,
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SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
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if (window) {
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std::cerr << "SDL_CreateWindow done" << std::endl;
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} else {
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std::cerr << "SDL_CreateWindow failed: [" << SDL_GetError() << "]" << std::endl;
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SDL_Quit();
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return -1;
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}
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SDL_GLContext gl_context = SDL_GL_CreateContext(window);
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int major, minor;
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SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &major);
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SDL_GL_GetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, &minor);
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std::cerr << "Requested OpenGL version: " << major << "." << minor << std::endl;
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if (gl_context) {
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std::cerr << "SDL_GL_CreateContext done" << std::endl;
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} else {
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std::cerr << "SDL_GL_CreateContext failed: [" << SDL_GetError() << "]" << std::endl;
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return -1;
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}
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if (SDL_GL_MakeCurrent(window, gl_context) != 0) {
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std::cerr << "SDL_GL_MakeCurrent failed: [" << SDL_GetError() << "]" << std::endl;
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SDL_GL_DeleteContext(gl_context);
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SDL_DestroyWindow(window);
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SDL_Quit();
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return -1;
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}
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SDL_GL_SetSwapInterval(1); // enable vsync
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GLenum glew_status = glewInit();
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if (glew_status == GLEW_OK) {
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std::cerr << "glewInit done" << std::endl;
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} else {
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std::cerr << "glewInit failed: [" << glewGetErrorString(glew_status) << std::endl;
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return -1;
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}
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const GLubyte * version = glGetString(GL_VERSION);
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glEnable(GL_BLEND);
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glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
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if (version) {
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std::cerr << "OpenGL version: [" << version << "]" << std::endl;
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} else {
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std::cerr << "OpenGL version not available" << std::endl;
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}
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IMGUI_CHECKVERSION();
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ImGui::CreateContext();
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ImGuiIO & io = ImGui::GetIO(); (void)io;
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io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
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ImGui::StyleColorsDark();
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ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
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ImGui_ImplOpenGL3_Init("#version 330");
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bool show_demo_window = true;
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bool show_another_window = false;
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ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
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float counter_value = 0.0f;
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// Main Loop
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bool done = false;
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while (!done) {
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/** poll + handle events */
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SDL_Event event;
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while (SDL_PollEvent(&event)) {
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ImGui_ImplSDL2_ProcessEvent(&event);
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if (event.type == SDL_QUIT)
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done = true;
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if ((event.type == SDL_WINDOWEVENT)
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&& (event.window.event == SDL_WINDOWEVENT_CLOSE)
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&& (event.window.windowID == SDL_GetWindowID(window)))
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{
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done = true;
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}
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}
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int w, h;
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SDL_GetWindowSize(window, &w, &h);
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glViewport(0, 0, w, h);
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glClearColor(clear_color.x * clear_color.w,
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clear_color.y * clear_color.w,
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clear_color.z * clear_color.w,
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clear_color.w);
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glClear(GL_COLOR_BUFFER_BIT);
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// draw dear imgui frame
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ImGui_ImplOpenGL3_NewFrame();
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ImGui_ImplSDL2_NewFrame();
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ImGui::NewFrame();
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ImGui::SetNextWindowPos(ImVec2(0, 0));
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ImGui::SetNextWindowSize(io.DisplaySize);
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ImGui::Begin("Background", nullptr,
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ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize
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| ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoBringToFrontOnFocus
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| ImGuiWindowFlags_NoNavFocus | ImGuiWindowFlags_NoDecoration);
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ImGui::End();
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// 1. big demo window
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if (show_demo_window)
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ImGui::ShowDemoWindow(&show_demo_window);
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// 2. show window that we create ourselves
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{
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static int counter = 0;
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ImGui::Begin("Hello, world!");
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ImGui::Text("This is totes useful text...");
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ImGui::Checkbox("demo window", &show_demo_window);
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ImGui::Checkbox("second window", &show_another_window);
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ImGui::SliderFloat("float", &counter_value, 0.0f, 1.0f);
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ImGui::ColorEdit3("clear color", (float*)&clear_color);
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if (ImGui::Button("Button"))
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++counter;
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ImGui::SameLine();
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ImGui::Text("counter = %d", counter);
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ImGui::Text("appl average %.3f ms/frame (%.1f fps)",
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1000.0f / io.Framerate, io.Framerate);
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ImGui::End();
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}
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// 3. another window
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if (show_another_window) {
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ImGui::Begin("another window", &show_another_window);
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ImGui::Text("hello from second window");
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if (ImGui::Button("close me"))
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show_another_window = false;
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ImGui::End();
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}
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// rendering
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ImGui::Render();
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ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
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SDL_GL_SwapWindow(window);
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}
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std::cerr << "cleanup.." << std::endl;
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ImGui_ImplOpenGL3_Shutdown();
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ImGui_ImplSDL2_Shutdown();
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ImGui::DestroyContext();
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SDL_GL_DeleteContext(gl_context);
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SDL_DestroyWindow(window);
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SDL_Quit();
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std::cerr << "All done, goodbye..." << std::endl;
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return 0;
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#ifdef NOPE2
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if (!glfwInit()) {
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std::cerr << "glfwInit failed!" << std::endl;
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return -1;
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}
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std::cout << "GLFW version: " << glfwGetVersionString() << std::endl;
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// configure glfw
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glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
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// this fails in nix-on-wsl
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//glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
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glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_ANY_PROFILE);
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// maybe:
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//glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
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// may need explicit hints
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//glfwWindowHint(GLFW_RED_BITS, 8)
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//glfwWindowHint(GLFW_GREEN_BITS, 8)
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//glfwWindowHint(GLFW_BLUE_BITS, 8)
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//glfwWindowHint(GLFW_ALPHA_BITS, 8)
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//glfwWindowHint(GLFW_DEPTH_BITS, 24)
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//glfwWindowHint(GLFW_STENCIL_BITS, 8)
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//glfwWindowHint(GLFW_DOUBLEBUFFER, GL_TRUE)
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//
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// try
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// $ glxinfo
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// to get framebuffer info
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// Not working because:
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// eglinfo
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// looks in
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// /run/opengl-driver/share/glvnd/egl_vendor.d
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// /etc/glvnd/egl_vendor.d
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// /usr/share/glvnd/egl_vendor.d
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//
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// these tell EGL which vendor libraries to load (mesa | nvidia)
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// create window
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GLFWwindow * window = glfwCreateWindow(800, 600, "simple opengl triangle", NULL, NULL);
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if (!window) {
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// getting error couldn't find framebuffer configuration matching requested
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// opengl context. used by GLX (opengl extension to x11).
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// defines things like: color depth, double buffering, stencil bits etc.
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const char * descr = nullptr;
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int code = glfwGetError(&descr);
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std::cerr << "glfwCreateWindow failed :code " << code << " :msg "
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<< (descr ? descr : "?unknown")
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<< std::endl;
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}
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#endif
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#ifdef NOPE
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if (SDL_Init(SDL_INIT_VIDEO
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| SDL_INIT_TIMER
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| SDL_INIT_GAMECONTROLLER) != 0)
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{
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std::cerr << "SDL_Init failed: " << SDL_GetError() << std::endl;
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return -1;
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}
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// OpenGL attributes
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SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
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SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
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SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
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SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
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// SDL window
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SDL_Window * window
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= SDL_CreateWindow("xo imgui ex1",
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SDL_WINDOWPOS_CENTERED,
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SDL_WINDOWPOS_CENTERED,
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800 /*width ?*/,
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600 /*height ?*/,
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SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
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SDL_GLContext gl_context = SDL_GLContext(window);
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SDL_GL_MakeCurrent(window, gl_context);
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SDL_GL_SetSwapInterval(1); // enable vsync.. (wut!?)
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// imgui
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IMGUI_CHECKVERSION();
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ImGui::CreateContext();
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ImGuiIO & io = ImGui::GetIO(); (void)io;
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ImGui::StyleColorsDark();
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ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
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#endif
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#ifdef NOPE
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// this gets: Failed to initialize OpenGL loader!
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ImGui_ImplOpenGL3_Init("#version 330");
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#endif
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}
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/* imgui_ex1.cpp */
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