Moving object with SFML - c++

Question

I started studying SFML from the book "SFML Game Development" by Arthur Moreira. I'm trying to move a circle object on the screen using the keyboard. Here is the code that is given:
#include <SFML/Graphics.hpp>
class Game
{
public:
Game();
void run();
private:
void ProcessEvents();
void update();
void render();
void handlePlayerInput(sf::Keyboard::Key key, bool isPressed);
private:
sf::RenderWindow myWindow;
sf::CircleShape myPlayer;
bool movingLeft, movingUp, movingRight, movingDown;
};
Game::Game() : myWindow(sf::VideoMode(640, 480), "SFML Game"), myPlayer()
{
myPlayer.setRadius(40.f);
myPlayer.setFillColor(sf::Color::Red);
myPlayer.setPosition(100.f, 100.f);
}
void Game::run()
{
while (myWindow.isOpen())
{
ProcessEvents();
update();
render();
}
}
void Game::ProcessEvents()
{
sf::Event event;
while (myWindow.pollEvent(event))
{
switch(event.type)
{
case sf::Event::KeyPressed : handlePlayerInput(event.key.code, true); break;
case sf::Event::KeyReleased : handlePlayerInput(event.key.code, false); break;
case sf::Event::Closed : myWindow.close(); break;
}
}
}
void Game::handlePlayerInput(sf::Keyboard::Key key, bool isPressed)
{
if (key == sf::Keyboard::W) movingUp = isPressed;
else if (key == sf::Keyboard::S) movingDown = isPressed;
else if (key == sf::Keyboard::A) movingLeft = isPressed;
else if (key == sf::Keyboard::D) movingRight = isPressed;
}
void Game::update()
{
sf::Vector2f movement(0.f, 0.f);
if (movingUp) movement.y -= 1.f;
if (movingDown) movement.y += 1.f;
if (movingLeft) movement.x -= 1.f;
if (movingRight) movement.x += 1.f;
myPlayer.move(movement);
}
void Game::render()
{
myWindow.clear();
myWindow.draw(myPlayer);
myWindow.display();
}
int main()
{
Game game;
game.run();
return 0;
}
Here is what my problem is:
In the function update(), I'm updating the direction on which the cicle should go. But the first time when I try to move for example to left, the circle goes to right. The opposite is the same. If I try to go to right in the beginning, the circle goes to left. When I try to go Up and Down the result is the same. So, as I said, when I go to left, it goes to right. But if I press again left, the movement stops and I can move the circle correctlyto left and right. I should do the same thing to repair the direction if I want to go Up and Down. Do I have a mistake in my code?
And my second question is:
In the update function I have written the code that is in the book. But if I want to go Up, I think I should add 1 to 'y', not to substract 1. And if I want to go down, shouldn't I substract 1? I think that the update function should look like this:
void Game::update()
{
sf::Vector2f movement(0.f, 0.f);
if (movingUp) movement.y += 1.f; //Here we should add 1
if (movingDown) movement.y -= 1.f; //Here we should substract 1
if (movingLeft) movement.x -= 1.f;
if (movingRight) movement.x += 1.f;
myPlayer.move(movement);
}
Maybe it will be better for you to run the code if you are able in order to see what exactly is happening.

Answer 1

Your moving variables aren't initialized, so some of them may initially have a true value.
You should set them all to false in your Game constructor.