Keyboard input problems with multiple players - c++

Question

I'm working on the motion for my paddles in my PONG clone and the program doesn't want to register SDL_KEYUP/DOWN sometimes. I think I have an idea of why this is but now how to fix it. So the way my game is looped currently I am using a state machine in my main() function that uses a Game class state which manages two paddles and a ball all of which are three different class instances. In side my Game class I run the events/logic/render from all three classes like so
void Game::events()
{
while (SDL_PollEvent(&event))
{
PlayerOne.events();
PlayerTwo.events();
Game_Ball.events();
}
}
void Game::logic()
{
PlayerOne.logic(delta.get_ticks());
PlayerTwo.logic(delta.get_ticks());
Game_Ball.logic();
}
void Game::render()
{
SDL_FillRect(screen, &screen->clip_rect, SDL_MapRGB(screen->format, 0, 0, 0));
PlayerOne.render();
PlayerTwo.render();
Game_Ball.render();
}
And the paddle class movement is managed like so (as fixed in the last question I had(:
void Paddle::events()
{
Uint8 *keystates = SDL_GetKeyState(NULL);
if (event.type == SDL_KEYDOWN)
{
if (player == 1)
{
if (keystates[SDLK_o] == 1)
{
yVel -= 100;
}
if (keystates[SDLK_k] == 1)
{
yVel += 100;
}
}
else
{
if (keystates[SDLK_w] == 1)
{
yVel -= 100;
}
if (keystates[SDLK_s] == 1)
{
yVel += 100;
}
}
}
if (event.type == SDL_KEYUP)
{
if (player == 1)
{
if (keystates[SDLK_o] == 0)
{
yVel += 100;
}
if (keystates[SDLK_k] == 0)
{
yVel -= 100;
}
}
else
{
if (keystates[SDLK_w] == 0)
{
yVel += 100;
}
if (keystates[SDLK_s] == 0)
{
yVel -= 100;
}
}
}
if (event.type == SDL_QUIT)
{
quit = true;
}
}
The problem here is that sometimes, if not most of the time, the keys don't react to move the player paddles up and down. but when they do it's less than half the time. I think this is because there is only a 1/3 chance that the program polls when a key is released or pressed, sometimes resulting in no change in the position. Basically, if PLAYERONE hits a key while Game is running PlayerTwo.events() it won't register the key press/release. Could this be a problem in the way I'm implementing the game loop in my main function?
int main(int argc, char* args[])
{
//init SDL
if (init() == false)
{
return 1;
}
//load everything
if (load_files() == false)
{
return 1;
}
delta.start();
currentState = new Game;
while (quit == false)
{
//handle state events
currentState->events();
// do state logic
currentState->logic();
//timer reset
delta.start();
//change state if needed
change_state();
//render state
currentState->render();
if (SDL_Flip(screen) == -1)
{
return 1;
}
}
clean_up();
return 0;
}
And here are the definitions and constructors
class Paddle
{
public:
int player;
SDL_Surface *sprite = NULL;
float x, y, w, h;
float yVel;
SDL_Rect *clip;
void events();
void logic(Uint32 deltaTicks);
void render();
Paddle();
~Paddle();
};
class Game : public GameState
{
private:
int server;
TTF_Font *score = NULL;
Paddle PlayerOne;
Paddle PlayerTwo;
Ball Game_Ball;
public:
SDL_Rect clip[2];
void events();
void logic();
void render();
Game();
~Game();
};
Game::Game()
{
//RESOURSES
PlayerOne.sprite = load_image("Game_sprite.png");
PlayerTwo.sprite = load_image("Game_sprite.png");
clip[0].x = 0;
clip[0].y = 0;
clip[0].w = 20;
clip[0].h = 20;
clip[1].x = 0;
clip[1].y = 20;
clip[1].w = 20;
clip[1].h = 100;
//PLAYER ONE
PlayerOne.x = 420;
PlayerOne.y = 100;
PlayerOne.w = 60;
PlayerOne.h = 100;
PlayerOne.clip = &clip[1];
PlayerOne.yVel = 0;
PlayerOne.player = 1;
//PLAYER TWO
PlayerTwo.x = 60;
PlayerTwo.y = 100;
PlayerTwo.w = 60;
PlayerTwo.h = 100;
PlayerTwo.clip = &clip[1];
PlayerTwo.yVel = 0;
PlayerTwo.player = 2;
//BALL
Game_Ball.Ball_Bound.x = 190;
Game_Ball.Ball_Bound.y = 190;
Game_Ball.Ball_Bound.w = 60;
Game_Ball.Ball_Bound.h = 60;
Game_Ball.clip = &clip[0];
}
Because that looks pretty clean to me. Other than another game loop implementation, what could I do to fix the keys not registering due to being in a different function? Or is it a loop implementation problem? If it is a loop problem, can you be through or include a reference as to how to fix it?

Answer 1

I don't see anything wrong in this code. However, the very possible cause might be simply limitation of how many keys are pressed on keyboard. Try using shift, ctrl and alt, keys for controls, they usually bypass the limitation.