SDL_GetKeyboardState called every frame #69

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1. chalonverse commented on Jul 10, 2024

   

   chalonverse

   on Jul 10, 2024

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   That’s true — the funny thing is that other parts of the SDL implementation actually also just goes ahead and calls SDL_GetKeyboardState repeatedly, like: https://github.com/libsdl-org/SDL/blob/fdc04708f1950ad76eff16fd47ffe67dcdc5ba04/src/video/windows/SDL_windowsevents.c#L1270
2. Haruu000 commented on Jul 10, 2024

   

   Haruu000

   on Jul 10, 2024

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   Hey can you look at the Linux makefile issue
3. nickenchev commented on Jul 10, 2024

   

   nickenchev

   on Jul 10, 2024

   Last edited by nickenchev

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   I'm assuming its because the call itself looks pretty inexpensive when you check the .c file its defined in. Though, the example you sent only occurs on key-up events, so so it wouldn't end up being a part of every loop iteration, it would likely only happen once at the end of a key-press/hold. Whereas the example I noticed it in the book gets called inside ProcessInput(), so its happening on absolutely every single pass of the game loop. Again, not really a big deal, its just something I notice in every sample SDL2 code, and considering how much gamedevs go out of their way to micro-optimize, I always wonder why stuff like this ends up everywhere.

   void Game::ProcessInput()
   {
   ...
       // Get state of keyboard
       const Uint8* state = SDL_GetKeyboardState(NULL);
       // If escape is pressed, also end loop
       if (state[SDL_SCANCODE_ESCAPE])
       {
           mIsRunning = false;
       }
   }
   `