simple-cpp-game-study/sfmldemo/main.cpp

#include "imgui.h"
#include "imgui-SFML.h"
#include <fmt/core.h>

#include <SFML/Graphics/CircleShape.hpp>
#include <SFML/Graphics/RenderWindow.hpp>
#include <SFML/System/Clock.hpp>
#include <SFML/Window/Event.hpp>

void ImGui_setup(sf::RenderWindow &window) {
  int res = ImGui::SFML::Init(window);
  if(res == 1) {
    fmt::print("ImGui returned result {}\n", res);
  } else {
    fmt::print("ImGui returned an error code={}\n", res);
  }
}

void ImGui_update(sf::RenderWindow &window, sf::Clock &deltaClock, sf::Time &tick) {
  ImGui::SFML::Update(window, deltaClock.restart());
  ImGui::ShowDemoWindow();
  ImGui::Begin("Hello, world!");

  std::string msg = fmt::format("Time: {}\n", tick.asSeconds());
  ImGui::Button(msg.c_str());
  ImGui::End();
}

void Window_update(sf::RenderWindow &window, sf::Shape &shape) {
    window.clear();
    window.draw(shape);
    ImGui::SFML::Render(window);
    window.display();
}

int main() {
  fmt::print("Setting up a window for you...\n");

  sf::RenderWindow window(sf::VideoMode(1920, 1080), "ImGui + SFML = <3");
  // window.setFramerateLimit(60);
  window.setVerticalSyncEnabled(true);

  ImGui_setup(window);

  sf::CircleShape shape(100.f);
  shape.setFillColor(sf::Color::Green);
  sf::Clock deltaClock;
  sf::Clock clock;
  sf::Time tick = clock.getElapsedTime();

  while (window.isOpen()) {
    sf::Event event;

    while (window.pollEvent(event)) {
      ImGui::SFML::ProcessEvent(window, event);

      if (event.type == sf::Event::Closed) {
        fmt::print("Exiting...\n");
        window.close();
      }
    }

    sf::Time since = clock.getElapsedTime();
    if(since - tick > sf::seconds(1)) {
      tick = since;
    }

    ImGui_update(window, deltaClock, tick);
    Window_update(window, shape);
  }

  ImGui::SFML::Shutdown();
}