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

#include "imgui.h"
#include "imgui-SFML.h"
#define _USE_MATH_DEFINES
#include <math.h>
#include <fmt/core.h>
#include <box2d/box2d.h>
#include <SFML/Graphics/Sprite.hpp>
#include <SFML/Graphics/Texture.hpp>
#include <SFML/Graphics/RenderWindow.hpp>
#include <SFML/System.hpp>
#include <SFML/Audio.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("Clock");
  sf::Vector2u size = window.getSize();
  ImGui::SetWindowPos(ImVec2(size.x - 150, 0));
  ImGui::SetWindowSize(ImVec2(150, 50));
  std::string msg = fmt::format("Time: {}\n", tick.asSeconds());
  ImGui::Button(msg.c_str());
  ImGui::End();
}

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

struct BoxTest {
  b2Body *groundBody;
  b2Body *body;
};

struct BoxTest Box2d_setup(b2World &world) {
  b2BodyDef groundBodyDef;
  groundBodyDef.position.Set(0.0f, -10.0f);
  b2Body *groundBody = world.CreateBody(&groundBodyDef);

  b2PolygonShape groundBox;
  groundBox.SetAsBox(50.0f, 10.0f);
  groundBody->CreateFixture(&groundBox, 0.0f);

  b2BodyDef bodyDef;
  bodyDef.type = b2_dynamicBody;
  bodyDef.position.Set(3.0f, 4.0f);
  b2Body *body = world.CreateBody(&bodyDef);

  b2PolygonShape dynamicBox;
  dynamicBox.SetAsBox(1.0f, 1.0f);
  b2FixtureDef fixtureDef;
  fixtureDef.shape = &dynamicBox;

  fixtureDef.density = 1.0f;
  fixtureDef.friction = 0.3f;

  body->CreateFixture(&fixtureDef);

  BoxTest box {groundBody, body};
  return box;
}


void Handle_events(sf::RenderWindow &window, BoxTest &box, sf::Sound &click) {
  sf::Event event;

  // is this a main event loop
  while (window.pollEvent(event)) {
    ImGui::SFML::ProcessEvent(window, event);

    switch(event.type) {

      case sf::Event::Closed:
        fmt::print("Exiting...\n");
        window.close();
        break;
      case sf::Event::KeyPressed:
        if(sf::Keyboard::isKeyPressed(sf::Keyboard::Left)) {
          b2Vec2 force(-200, 1000);
          box.body->ApplyForceToCenter(force, true);
          box.body->ApplyTorque(100.0f, true);
          click.play();
        } else if(sf::Keyboard::isKeyPressed(sf::Keyboard::Right)) {
          b2Vec2 force(200, 1000);
          box.body->ApplyForceToCenter(force, true);
          box.body->ApplyTorque(-100.0f, true);
          click.play();
        }
        break;
      case sf::Event::MouseButtonPressed:
        if(sf::Mouse::isButtonPressed(sf::Mouse::Left)) {
          b2Vec2 force(-200, 1000);
          box.body->ApplyForceToCenter(force, true);
          box.body->ApplyTorque(100.0f, true);
          click.play();
        } else if (sf::Mouse::isButtonPressed(sf::Mouse::Right)) {
          b2Vec2 force(200, 1000);
          box.body->ApplyForceToCenter(force, true);
          box.body->ApplyTorque(-100.0f, true);
          click.play();
        }
        break;
    }
  }
}

sf::Time Update_entities(sf::RenderWindow &window, b2World &world, sf::Clock &clock, sf::Clock &deltaClock, sf::Time &tick, BoxTest &box,  sf::Sprite &player) {
  sf::Vector2u winSize = window.getSize();
  float timeStep = 1.0f / 60.0f;
  int velocityIterations = 6;
  int positionIterations = 2;
  sf::Time since = clock.getElapsedTime();
  sf::Time nextTick = since - tick > sf::seconds(1) ? since : tick;

  world.Step(timeStep, velocityIterations, positionIterations);
  b2Vec2 position = box.body->GetPosition();
  float angle = box.body->GetAngle();

  player.setPosition(position.x * 100.0f, winSize.y - position.y * 100.0f);
  player.setRotation(angle * 180.0f / M_PI);

  ImGui_update(window, deltaClock, tick);
  Window_update(window, player);

  return nextTick;
}


void Create_player(sf::RenderWindow &window, sf::Sprite &player, sf::Texture &texture) {
  if(!texture.loadFromFile("sprite.png")) {
    fmt::print("Error loading sprite!");
  }

  texture.setSmooth(true);

  player.setTexture(texture);

  // position the prite
  sf::Vector2u winSize = window.getSize();
  player.setPosition(winSize.x / 2, winSize.y / 2);
  player.setOrigin(50.f, 50.f);
}

int main() {
  fmt::print("Setting up a window for you...\n");
  sf::ContextSettings settings;
  settings.antialiasingLevel = 8;

  sf::RenderWindow window(sf::VideoMode(1920, 1080), "Simple Game Demo", sf::Style::Default, settings);
  window.setFramerateLimit(60);
  window.setVerticalSyncEnabled(true);
  ImGui_setup(window);

  sf::SoundBuffer buffer;
  if(!buffer.loadFromFile("click.mp3")) {
    fmt::print("Failed to load click.ogg!\n");
  }
  sf::Sound click;
  click.setBuffer(buffer);

  sf::Clock deltaClock;
  sf::Clock clock;
  sf::Time tick = clock.getElapsedTime();

  sf::Sprite player;
  sf::Texture texture;
  Create_player(window, player, texture);

  b2Vec2 gravity(0.0f, -10.0f);
  b2World world(gravity);
  BoxTest box = Box2d_setup(world);

  while (window.isOpen()) {
    Handle_events(window, box, click);
    // preparing for refactoring this into a class or struct for everything
    tick = Update_entities(window, world, clock, deltaClock, tick, box, player);
  }

  ImGui::SFML::Shutdown();
}