Question

I am making a 2D game where we are supposed to control the character through arrow keys.

        if((win.GetInput().IsKeyDown(sf::Key::Down)))
        {
            y = y + Speed;
        }

        if((win.GetInput().IsKeyDown(sf::Key::Left)))
        {
            x = x - Speed;
        }

I have set Speed to 10. And then a i use the Sprite.SetPosition(x,y) to actually animate my character.

Everything works fine. But the problem is whenever i press an arrow key, the character moves for 1/2 seconds, stops for about 1/2 seconds and then moves again smoothly. This happens whenever i press any arrow key.

And yes, i am using a while loop on top to handle multiple events simultaneously.

I hope my question was clear enough. Please help me out!

Thanks.

Answer 1

I think you’re not handling events the right way. What you’re doing here is checking on each event (which could be keyboard input or not) whether the sf::Key::Down key is pressed (and the same for sf::Key::Left).

Firstly, it’s not effective, because you don’t get the result you want.
Secondly, it performs useless checks admitting that the events could be mouse moves, mouse clicks or anything else : checking whether those keys are pressed in such cases is pointless for your program.

I can’t see your whole code, but you should try something of this taste as your main loop :

bool isMovingLeft = false;
bool isMovingDown = false;
sf::Event event;

while (win.IsOpen())
{
    // While window catches events...
    while(win.GetEvent(event))
    {
         // If the caught event is a click on the close button, close the window
         if (event.Type == sf::Event::Closed)
             win.Close();
         // If it's a key press, check which key and move consequently
         else if (event.Type == sf::Event::KeyPressed)
         {
              if(event.Key.Code == sf::Key::Left)
                   isMovingLeft = true;
              else if(event.Key.Code == sf::Key::Down)
                   isMovingDown = true;
         }
         // If it's a key release, stop moving in the following direction
         else if (event.Type == sf::Event::KeyReleased)
         {
              if(event.Key.Code == sf::Key::Left)
                   isMovingLeft = false;
              else if(event.Key.Code == sf::Key::Down)
                   isMovingDown = false;
         }    
    }

    // Now that we have caught events, we move the lil' thing if we need to.
    if(isMovingLeft)
          x = x - SPEED;
    if(isMovingDown)
          y = y - SPEED;


    win.Clear();

    // Draw things on the screen...

    win.Display();
}

In this code, the whole process is split in two parts :

• We first intercept the user input to see if we need to change the moving state of the thing.
• Then, once every event has been caught and thoroughly analyzed, we move the thing if it has to. It is done through two bools (that you may need to increase to four if you want a four-direction control. If you want to handle diagonal directions, it would be wiser to use an enum than eight bool, which begins to be rather memory-consuming for such a simple task.)

Note : you will maybe notice that I changed “Speed” to “SPEED”. I can’t see if it was a define, a const var or simply a var from the code you have given, but the best option would be one of the two first ones. I prefer using #define for such things, to make constants easily reachable (as they’re put in the preprocessor) and the fully capped writing make it more differentiable from classic vars once in the code. But that’s just coding style we’re talking of here 🙂