CODEWITHSUNDEEP
c++inputsdl-2
Wulfo
Wulfo

Reputation: 23

How to get persistent input in SDL2 c++

So I noticed that when getting input with SDL_GetKeyboardState(NULL), when holding a specific button, it is going to first write outlets say a, and after 1 second its gonna continue aaaaaaaa normally. I want to when I hold the button a that it automatically goes aaaaaa. Here is a video if you don't understand my poor explanations: https://streamable.com/oub0w3

There is a delay between it writes out first a, and writing out aaaaa about 1 second. How can I change that? (I want there to be no delay)

Here is my code:

while (gameRunning) {
    SDL_Event event;
    const Uint8* keystates = SDL_GetKeyboardState(NULL);
    while (SDL_PollEvent(&event)) {
        if (event.type == SDL_QUIT) {
            gameRunning = false;
        }
        if (keystates[SDL_SCANCODE_W]) {
            entities[0].setY(entities[0].getY() - 1);
        }
        if (keystates[SDL_SCANCODE_S]) {
            entities[0].setY(entities[0].getY() + 1);
        }
        if (keystates[SDL_SCANCODE_A]) {
            entities[0].setX(entities[0].getX() - 1);
        }
        if (keystates[SDL_SCANCODE_D]) {
            entities[0].setX(entities[0].getX() + 1);
        }
}

Upvotes: 1

Views: 413

Answers (2)

ZeroZ30o
ZeroZ30o

Reputation: 396

If you want the repetition to start immediately, you need to make your own implementation of the repeating letters.

The additional "a" characters you receive as events are (I assume) generated by the operating system, so unless you have some settings on your OS you can change to make repetition start immediately, you need your program to do it.

(I am assuming SDL is not the one generating these characters, which could be a possibility)

To do this, you would make a system check the amount of time elapsed and kept track of how long keys are being pressed, and outputting "key" events that it generated itself, much like the OS is doing.

Upvotes: 0

HolyBlackCat
HolyBlackCat

Reputation: 96699

You're misusing SDL_GetKeyboardState(nullptr).

It should be used in the main loop, not in the event loop:

while (gameRunning)
{
    SDL_Event event;
    while (SDL_PollEvent(&event))
    {
        if (event.type == SDL_QUIT)
            gameRunning = false;
    }
    const std::uint8_t *keystates = SDL_GetKeyboardState(nullptr);
    if (keystates[SDL_SCANCODE_W])
        entities[0].setY(entities[0].getY() - 1);
    if (keystates[SDL_SCANCODE_S])
        entities[0].setY(entities[0].getY() + 1);
    // An so on...
}

Upvotes: 3

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