Ball.cpp

#include <SFML/Graphics.hpp>

#include "Ball.hpp"

Ball::Ball(int x, int y) : Entity(x, y, 10, 10, 4) {}

void Ball::checkCollision(int x, int y) {
	;
}

void Ball::checkCollision(sf::FloatRect rect) {
    if (getGlobalBounds().intersects(rect)) {
        setSpeed(-getSpeed());
    }
}

void Ball::update() {
    move(getSpeed(), 0);
}

void Ball::update(sf::Keyboard::Key keyUp, sf::Keyboard::Key keyDown) {
	;
}

Ball.hpp

#ifndef BALL
#define BALL

#include <SFML/Graphics.hpp>

#include "Bat.hpp"
#include "Entity.hpp"

class Ball : public Entity {
public:
    Ball(int x, int y);

    void checkCollision(sf::FloatRect rect);
    void checkCollision(int x, int y);
    void update();
    void update(sf::Keyboard::Key keyUp, sf::Keyboard::Key keyDown);
};

#endif

Bat.cpp

#include <SFML/Graphics.hpp>
#include <SFML/Window.hpp>

#include "Bat.hpp"

Bat::Bat(int x, int y) : Entity(x, y, 10, 100, 6) {}

void Bat::checkCollision(int x, int y) {
    if (getX() < 0) {
        setPosition(0, getY());
    } else if (getX() + getWidth() > x) {
        setPosition(x - getWidth(), getY());
    }
    if (getY() < 0) {
        setPosition(getX(), 0);
    } else if (getY() + getHeight() > y) {
        setPosition(getX(), y - getHeight());
    }
}

void Bat::update(sf::Keyboard::Key keyUp, sf::Keyboard::Key keyDown) {
    if (sf::Keyboard::isKeyPressed(keyUp)) {
        move(0, -4);
    }
    if (sf::Keyboard::isKeyPressed(keyDown)) {
        move(0, 4);
    }
}

void Bat::checkCollision(sf::FloatRect rect) {
    
}

void Bat::update() {

}

Bat.hpp

#ifndef BAT
#define BAT

#include <SFML/Graphics.hpp>
#include "Entity.hpp"

class Bat : public Entity {
public:
    Bat(int x, int y);

    void checkCollision(int x, int y);
    void checkCollision(sf::FloatRect rect);
    void update(sf::Keyboard::Key keyUp, sf::Keyboard::Key keyDown);
    void update();
};

#endif

Entity.cpp

#include <SFML/Graphics.hpp>

#include "Entity.hpp"

Entity::Entity(int x, int y, int width, int height, int speed) {
    setSize(sf::Vector2f(width, height));
    setPosition(x, y);

    this->speed = speed;
}

int Entity::getX() {
    return getGlobalBounds().left;
}

int Entity::getY() {
    return getGlobalBounds().top;
}

int Entity::getWidth() {
    return getGlobalBounds().width;
}

int Entity::getHeight() {
    return getGlobalBounds().height;
}

int Entity::getSpeed() {
    return speed;
}

void Entity::setSpeed(int speed) {
    this->speed = speed;
}

Entity.hpp

#ifndef ENTITY
#define ENTITY

#include <SFML/Graphics.hpp>

class Entity : public sf::RectangleShape {
public:
    Entity(int x, int y, int width, int height, int speed);

    virtual void update() = 0;
    virtual void update(sf::Keyboard::Key keyUp, sf::Keyboard::Key keyDown) = 0;
    virtual void checkCollision(sf::FloatRect rect) = 0;
    virtual void checkCollision(int x, int y) = 0;
    void setSpeed(int speed);
    int getX();
    int getY();
    int getWidth();
    int getHeight();
    int getSpeed();
 
private:
    int speed;
};

#endif

main.cpp

#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
#include <iostream>

#include "Bat.hpp"
#include "Ball.hpp"

constexpr int WIDTH = 640, HEIGHT = 480;
static bool paused = false;

void draw(sf::RenderWindow * window, std::vector<Entity*> &entities) {
    window->clear();

    for (int i = 0; i < 3; i++) {
        window->draw(*entities[i]);
    }

    window->display();
}

void update(sf::RenderWindow * window, std::vector<Entity*> &entities) {
    sf::Event event;

    while (window->pollEvent(event)) {
        if (event.type == sf::Event::Closed) {
            window->close();
        } else if (event.type == sf::Event::LostFocus) {
            paused = true;
        } else if (event.type == sf::Event::GainedFocus) {
            paused = false;
        }
    }

    if (!paused) {
        if (sf::Keyboard::isKeyPressed(sf::Keyboard::Escape)) {
            window->close();
        }

        for (int i = 0; i < 2; i++) {
            entities[i]->checkCollision(sf::FloatRect(WIDTH, HEIGHT, 0, 0));
            entities[2]->checkCollision(entities[i]->getGlobalBounds());
        }
        entities[0]->update(sf::Keyboard::Comma, sf::Keyboard::O);
        entities[1]->update(sf::Keyboard::Up, sf::Keyboard::Down);
        entities[2]->update();
    }

}

int main(int argc, char ** argv) {
    sf::VideoMode mode(WIDTH, HEIGHT);
    sf::RenderWindow window;
    Bat bat1(10, HEIGHT / 2 - 50);
    Bat bat2(WIDTH - 20, HEIGHT / 2 - 50);
    Ball ball(WIDTH / 2, HEIGHT / 2);
    std::vector<Entity*> entities;
    entities = {&bat1, &bat2, &ball};

    window.create(mode, "SAT");
    window.setVerticalSyncEnabled(true);

    while (window.isOpen()) {
        draw(&window, entities);
        update(&window, entities);
    }

    return 0;
}