Zaznaczanie prostokątnego obszaru przy pomocy lewego przycisku myszy

#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
#include <iostream>
using namespace std;

sf::Vector2i mousePosition;
sf::Vector2i startMousePosition;
sf::RectangleShape rect;
sf::RenderWindow * window = nullptr;

int main() {
   
    window = new sf::RenderWindow( sf::VideoMode( 1280, 720 ), "RECT" );
   
    while( window->isOpen() ) {
       
        mousePosition = sf::Mouse::getPosition( * window ); // Pobierz aktualną pozycję myszy względem bieżącego okna
       
        sf::Event event;
        while( window->pollEvent( event ) ) {
           
            if( event.type == sf::Event::MouseButtonPressed ) {
                if( event.mouseButton.button == sf::Mouse::Left ) {
                   
                    startMousePosition = sf::Mouse::getPosition( * window );
                }
            }
           
        }
       
        int start_x, start_y, end_x, end_y;
       
        if( mousePosition.x > startMousePosition.x ) {
            start_x = startMousePosition.x;
            end_x = mousePosition.x;
        }
        else {
            start_x = mousePosition.x;
            end_x = startMousePosition.x;
        }
       
        if( mousePosition.y > startMousePosition.y ) {
            start_y = startMousePosition.y;
            end_y = mousePosition.y;
        }
        else {
            start_y = mousePosition.y;
            end_y = startMousePosition.y;
        }
       
        cout << "selected area: \n";
        cout << "start: " << start_x << ", " << start_y << "\n";
        cout << "end: " << end_x << ", " << end_y << "\n";
        cout << "\n\n";
       
        rect = sf::RectangleShape( sf::Vector2f( end_x - start_x, end_y - start_y ) );
        rect.setPosition( start_x, start_y );
       
        window->clear();
        window->draw( rect );
        window->display();
    }
   
    return 0;
}

void testSelectingFunction() {
   
    sf::Vector2i mousePosition;
    sf::Vector2i startMousePosition;
    sf::RectangleShape rect;
    sf::RenderWindow * window = nullptr;
   
    enum class selection_states { none, select };
    selection_states selection_state = selection_states::none;
   
    window = new sf::RenderWindow( sf::VideoMode( 1280, 720 ), "RECT" );
   
    while( window->isOpen() ) {
       
        mousePosition = sf::Mouse::getPosition( * window ); // Pobierz aktualną pozycję myszy względem bieżącego okna
       
        sf::Event event;
        while( window->pollEvent( event ) ) {
           
            if( event.type == sf::Event::MouseButtonPressed ) {
                if( event.mouseButton.button == sf::Mouse::Left ) {
                   
                    startMousePosition = sf::Mouse::getPosition( * window );
                } selection_state = selection_states::select;
            }
           
            if( event.type == sf::Event::MouseButtonReleased ) {
                if( event.mouseButton.button == sf::Mouse::Left ) {
                    selection_state = selection_states::none;
                }
            }
        }
       
        if( selection_state == selection_states::select ) {
           
            int start_x, start_y, end_x, end_y;
           
            if( mousePosition.x > startMousePosition.x ) {
                start_x = startMousePosition.x;
                end_x = mousePosition.x;
            }
            else {
                start_x = mousePosition.x;
                end_x = startMousePosition.x;
            }
           
            if( mousePosition.y > startMousePosition.y ) {
                start_y = startMousePosition.y;
                end_y = mousePosition.y;
            }
            else {
                start_y = mousePosition.y;
                end_y = startMousePosition.y;
            }
           
            cout << "selected area: \n";
            cout << "start: " << start_x << ", " << start_y << "\n";
            cout << "end: " << end_x << ", " << end_y << "\n";
            cout << "\n\n";
           
            rect = sf::RectangleShape( sf::Vector2f( end_x - start_x, end_y - start_y ) );
            rect.setPosition( start_x, start_y );
        }
       
        window->clear();
        if( selection_state == selection_states::select )
             window->draw( rect );
       
        window->display();
    }
   
}

#include <SFML/Window.hpp>
#include <SFML/Graphics.hpp>
#include <algorithm>  // std::min, max

int main() {
    sf::RenderWindow window( sf::VideoMode( 1280, 720 ), "RECT" );
   
    sf::Vector2i startMousePosition;
    bool selection_state = false;
   
    while( window.isOpen() ) {
       
        sf::Vector2i mousePosition = sf::Mouse::getPosition( window );
       
        sf::Event event;
        while( window.pollEvent( event ) ) {
            if( event.type == sf::Event::Closed )
                 window.close();
           
            if( event.type == sf::Event::MouseButtonPressed ) {
                if( event.mouseButton.button == sf::Mouse::Left ) {
                   
                    startMousePosition = sf::Mouse::getPosition( window );
                    selection_state = true;
                }
            }
           
            if( event.type == sf::Event::MouseButtonReleased ) {
                if( event.mouseButton.button == sf::Mouse::Left ) {
                    selection_state = false;
                }
            }
        }
       
        window.clear();
       
        if( selection_state ) {
            int start_x = std::min( startMousePosition.x, mousePosition.x );
            int start_y = std::min( startMousePosition.y, mousePosition.y );
            int end_x = std::max( startMousePosition.x, mousePosition.x );
            int end_y = std::max( startMousePosition.y, mousePosition.y );
           
            // Nie ma sensu przechowywać RectangleShape dłużej niż to potrzebne
            sf::RectangleShape rect( sf::Vector2f( end_x - start_x, end_y - start_y ) );
            rect.setPosition( start_x, start_y );
            window.draw( rect );
        }
       
        window.display();
    }
   
    return 0;
}

void testSelectingFunction() {
    // Local mouse position
    sf::Vector2i mousePosition;
    sf::Vector2i startMousePosition;
   
    // Global mouse position
    sf::Vector2f worldMousePosition;
    sf::Vector2f startWorldMousePosition;
   
    sf::RectangleShape rect;
    sf::RenderWindow * window;
   
    bool selection_state = false;
   
    window = new sf::RenderWindow( sf::VideoMode( 1280, 720 ), "RECT" );
   
    while( window->isOpen() ) {
       
        mousePosition = sf::Mouse::getPosition( * window ); // Pobierz aktualną pozycję myszy względem bieżącego okna
        worldMousePosition = window->mapPixelToCoords( mousePosition );
       
        sf::Event event;
        while( window->pollEvent( event ) ) {
           
            if( event.type == sf::Event::MouseButtonPressed ) {
                if( event.mouseButton.button == sf::Mouse::Left ) {
                   
                    startMousePosition = sf::Mouse::getPosition( * window );
                    startWorldMousePosition = window->mapPixelToCoords( startMousePosition );
                } selection_state = true;;
            }
           
            if( event.type == sf::Event::MouseButtonReleased ) {
                if( event.mouseButton.button == sf::Mouse::Left ) {
                    selection_state = false;
                    // action
                }
            }
        }
       
        if( selection_state == true ) {
           
            int start_x = std::min( ceil( startWorldMousePosition.x / tileSide ), ceil( worldMousePosition.x / tileSide ) );
            int start_y = std::min( ceil( startWorldMousePosition.y / tileSide ), ceil( worldMousePosition.y / tileSide ) );
            int end_x = std::max( ceil( startWorldMousePosition.x / tileSide ), ceil( worldMousePosition.x / tileSide ) );
            int end_y = std::max( ceil( startWorldMousePosition.y / tileSide ), ceil( worldMousePosition.y / tileSide ) );
           
            cout << "selected area: \n";
            cout << "start: " << start_x << ", " << start_y << "\n";
            cout << "end: " << end_x << ", " << end_y << "\n";
            cout << "\n\n";
           
            rect = sf::RectangleShape( sf::Vector2f(( end_x - start_x ) * tileSide,( end_y - start_y ) * tileSide ) );
            rect.setPosition( start_x * tileSide, start_y * tileSide );
        }
       
        window->clear();
        if( selection_state == true )
             window->draw( rect );
       
        window->display();
    }
   
    delete window;
   
}