CODEWITHSUNDEEP
c++ckeyboardsdlsdl-2
mike11
mike11

Reputation: 17

SDL_GetKeyboardState does not return the current state of a key

I'm using SDL 2.0, and I can't get SDL_GetKeyboardState to work as expected. The player should move up and down, but this is not happening. 

void Movements() {

    const Uint8  *currentKey = SDL_GetKeyboardState(NULL);  // Point has to be defined once

    if (currentKey[SDLK_w]){
            PlayerPaddle.y = PlayerPaddle.y+2;
        }

    if (currentKey[SDLK_s]){
            PlayerPaddle.y = PlayerPaddle.y+2;
        }

}

int main(int argc, char* args[]) {

    main_menue();

    bool running = true;

    while (running == true) {
        SDL_PollEvent(&occur);

        if (occur.type == SDL_QUIT) {  // Closes the window, if user stops running
            running = false;
        }
        Movements();
    }
}

I also tried to pump up the event loop with PumpEvents, but still can't read the current state of a key. I also found this on stackoverflow (SDL_GetKeyboardState not working), but the answers there did not help me find a solution. Did I miss something here? Am I really blind and misunderstood something?

Upvotes: 0

Views: 2025

Answers (1)

Leiaz
Leiaz

Reputation: 2917

Assuming SDL_Init() and other declarations were just removed when pasting here.

First, you are not using correct indexes. As explained in the documentation here : "Indexes into this array are obtained by using SDL_Scancode values." But you are using SDL_Keycode values.

The other problem is that you are using the non-blocking SDL_PollEvent and calling Movements() at each iteration, and don't have any kind of blocking or waiting in your loop. This will use 100% CPU, running as fast as possible, and you'll end up with a pretty high y value ...

Instead of the array returned by SDL_GetKeyboardState you could use the key events. If occur.type is for instance SDL_KEYDOWN, occur.key.keysym.sym is the SDL_Keycode of the pressed key. Look at the documentation of SDL_Event and other event types for the details.

You should also add a SDL_Delay to your loop.

Another way is to use SDL_WaitEvent which only returns when an event occurs. Then you process the event, if it is a key press do some action depending on the key, etc ...

Upvotes: 1

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