Box2D positioning issue

[GeorgeR]

Hi! I am having a problem with positioning using Box2D. Every time I press the left mouse button a box should be displayed at the click coordinates. But the problem is that the box is displayed to the right of the click.

Here is the code:

#include <SFML/Graphics.hpp>
#include <Box2D/Box2D.h>

static const double SCALE = 32.0;

void createBox(b2World& world, double mouseX, double mouseY);

int main()
{
    sf::RenderWindow window(sf::VideoMode(800, 600), "SFML 2.2", sf::Style::Close);
    window.setFramerateLimit(60);

    sf::RectangleShape shape;
    shape.setFillColor(sf::Color::Red);
    shape.setSize(sf::Vector2f(16.0, 16.0));

    b2Vec2 gravity(0.0, 9.8);

    b2World world(gravity);
    world.SetGravity(gravity);

    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
            {
                window.close();
            }

            if (sf::Mouse::isButtonPressed(sf::Mouse::Left))
            {
                double mouseX = sf::Mouse::getPosition().x;
                double mouseY = sf::Mouse::getPosition().y;

                createBox(world, mouseX , mouseY);
            }
        }

        window.clear();

        for (b2Body* bodyIterator = world.GetBodyList(); bodyIterator != 0; bodyIterator = bodyIterator->GetNext())
        {
            if (bodyIterator->GetType() == b2_dynamicBody)
            {
                shape.setPosition(SCALE * bodyIterator->GetPosition().x, SCALE * bodyIterator->GetPosition().y);
                shape.setRotation(bodyIterator->GetAngle() * 180 / b2_pi);

                window.draw(shape);
            }
        }

        world.Step(1/60.0, 8, 3);
        window.display();
    }

    return 0;
}

void createBox(b2World& world, double mouseX, double mouseY)
{
    b2BodyDef bodyDef;
    bodyDef.position = b2Vec2(mouseX / SCALE, mouseY / SCALE );
    bodyDef.type = b2_dynamicBody;

    b2Body* body = world.CreateBody(&bodyDef);

    b2PolygonShape box;
    box.SetAsBox(16.0 / SCALE, 16.0 / SCALE);

    b2FixtureDef fixtureDef;
    fixtureDef.density = 1.5;
    fixtureDef.friction = 0.7;
    fixtureDef.shape = &box;

    body->CreateFixture(&fixtureDef);
}
 

[Laurent]

Please read the API documentation, especially about sf::Mouse::getPosition.

And don't mix events with real-time inputs, this is a really bad habit. As an exemple, hold the left button and press any key: for every key press a new box will be created, although you don't make new clicks.

[GeorgeR]

Thanks!
Solved it now!