Mouse position with screen scrolling in SFML

问题

Im trying to create a block placement with snap to grid. Everything is working, and in my head this should update the position of the mouse relative to the window each frame right?

sf::Vector2i position = sf::Mouse::getPosition(window.mywindow);

//get position
int xSnap = (position.x / gridWidth) * gridWidth;
int ySnap = (position.y / gridHeight) * gridHeight;

But i also have screen scrolling using

if (player.playerSprite.getPosition().x + 16 > screenDimensions.x / 2)
        position.x = player.playerSprite.getPosition().x + 16;
    else
        position.x = screenDimensions.x / 2;

    //Y
    if (player.playerSprite.getPosition().y + 16 > screenDimensions.y / 2)
        position.y = player.playerSprite.getPosition().y + 16;
    else
        position.y = screenDimensions.y / 2;

When the screen scrolls either way from its original position it doesnt update the mouse position, so for example, lets say the window size is 800x600, within that 800x600 window the position works fine, but lets say my sprite move 200px right (it starts scrolling when the sprite reaches the middle of the screen) past the original position, the object im placing using this code then appears 200px to the left of the mouse. Same happens with the y axis.

I hope that make sense

回答1:

You need to call window.mapPixelToCoords() to transform your pixel position to the coordinate system of your view.

sf::Vector2i pixel_pos = sf::Mouse::getPosition(window.mywindow);
sf::Vector2f coord_pos = window.mywindow.mapPixelToCoords(pixel_pos);

And as a general advice: Don't use public class members - mywindow and playerSprite should not be accessible from the outside.

来源：https://stackoverflow.com/questions/21554023/mouse-position-with-screen-scrolling-in-sfml