How to make a loading screen state transition to game level state? - c++

Question

I am trying to make my basic loading screen transition over to game level screen. So what i wanted to do is, once the loading screen is active (or has appeared onscreen), I want at this point to start loading my game state. What it is doing at the moment is loading everything at the start, and this does take a while.
So currently my project starts off with a main menu. Then when i press enter, its starts the loading screen. I have my manual state change using keypresses like so:
void Game::update()
{
static bool enterPreviouslyPressed = false;
static bool escapePreviousPressed = false;
const Uint8 *keys = SDL_GetKeyboardState(NULL);
if (keys[::SDL_SCANCODE_ESCAPE] && !escapePreviousPressed && typeid(*fsm->getState()) == typeid(GameState))
{
fsm->setState(menuState);
}
else if (keys[::SDL_SCANCODE_RETURN] && !enterPreviouslyPressed && typeid(*fsm->getState()) == typeid(MainMenuState))
{
fsm->setState(loadingState);
}
else if ((keys[::SDL_SCANCODE_RETURN] && !enterPreviouslyPressed) && typeid(*fsm->getState()) == typeid(LoadScreenState))
{
fsm->setState(gameState);
}
else if (keys[::SDL_SCANCODE_ESCAPE] && !escapePreviousPressed && typeid(*fsm->getState()) == typeid(MainMenuState))
{
exit(0);
}
enterPreviouslyPressed = keys[::SDL_SCANCODE_RETURN] != 0;
escapePreviousPressed = keys[::SDL_SCANCODE_ESCAPE] != 0;
fsm->update();
}
I did this to initially does this so i could change states manually to check that everything works. I was wondering if there was an easy(ish) way, like boolean flags for example or another simpler way to do this. I wasn't able find any tutorials online so wondering if someone knows the best solution as to how to do this. I did see a question on here, kindda similar but I wasn't sure if it answered my question as the person did this in threads which I am not familiar with how to implement. Apologies if I dont seem to have the logic correct - so please advise otherwise.

Answer 1

Looks fairly standard, except I would simplify it by keeping two keyboard state variables declared as class variables, like:
const Uint8 *curKeys = SDL_GetKeyboardState(NULL), *prevKeys;
// ...
void Game::update() {
prevKeys = curKeys;
curKeys = = SDL_GetKeyboardState(NULL);
//and so then compare curKeys to prevkeys
//and ditch the booleans
// ...
}