You usually only need 1 event loop (executing SDL_PollEvent()) so you shouldn’t need to create another one in your render function.
Like I wrote in my previous post: update/logic and rendering should be separated, so event polling shouldn’t be handled in the render function either way.
When it comes to pausing in games, when a game is in a paused state, in the end it all comes to not updating the game and its game objects. Event polling still need to be handled though, so that the player can unpause/resume the game by pressing, for example, the P key on the keyboard. But when it comes to other input, like player movement code, like the arrow keys for example, clicking with the mouse on HUD button(s) on the screen etc should be temporarially disabled.
Below I’ve added another example code on how to handle a paused state in a game. What the code basically does is leaving the update function earlier, if IsPaused is true (i.e, the game is paused). If not, the rest of the code in Update() is executed, effectively updating the game and its game objects.
Also note that I’ve added another way of handling input from the keyboard. Instead of using the event type SDL_KEYDOWN, I’ve used the SDL_GetKeyboardState() function, to retrieve the current state of all the keys on the keyboard.
After the state is retrieved, the new function KeyPressed() can be used to check against a specific key on the keyboard, and then act accordingly to that result.
View code example
// Variables
bool Running = false;
bool IsPaused = false;
bool Keys[SDL_NUM_SCANCODES];
memset(Keys, false, sizeof(Keys));
//////////////////////////////////////////////////////////////////////////
// Function declarations
void HandleEvents (void);
void Update (void);
void Render (void);
bool KeyPressed (const SDL_Scancode Scancode);
//////////////////////////////////////////////////////////////////////////
int main(int argc, char *argv[])
{
Create();
while(Running)
{
Update();
Render();
}
Destroy();
return 0;
}
//////////////////////////////////////////////////////////////////////////
// Function bodies
void HandleEvents(void)
{
while(SDL_PollEvent(&Event))
{
switch(Event.type)
{
case SDL_QUIT:
{
Running = false;
break;
}
default:
break;
}
}
// Get the current keyboard state and save it into the keys array
memcpy(Keys, SDL_GetKeyboardState(nullptr), SDL_NUM_SCANCODES * sizeof(bool));
}
void Update(void)
{
HandleEvents();
if(KeyPressed(SDL_SCANCODE_P))
{
IsPaused = !IsPaused;
if(IsPaused)
Musicplayer.Pause();
else
MusicPlayer.Resume();
}
if(IsPaused)
return;
// Update all the game objects
CurrentMap.Update();
Player.Update();
Enemy.Update();
}
void Render(void)
{
SDL_SetRenderDrawColor(pRenderer, 255, 255, 255, 255);
SDL_RenderClear(pRenderer);
// Render all the game objects here
CurrentMap.Render();
Player.Render();
Enemy.Render();
if(IsPaused)
{
const SDL_Rect AlphaRect = {0, 0, SCREEN_WIDTH, SCREEN_HEIGHT};
const SDL_Rect PauseTexPos = { (SCREEN_WIDTH / 2) - (PauseTexWidth / 2),
(SCREEN_HEIGHT / 2) - (PauseTexHeight / 2),
(PauseTexWidth),
(PauseTexHeight)};
// Render a black, half-transparent, background to cover the game world and its game objects
SDL_SetRenderDrawColor(pRenderer, 0, 0, 0, 128);
SDL_RenderFillRect(pRenderer, &AlphaRect);
// And render the pause texture in the middle of the window
SDL_RenderCopy(pRenderer, PauseTex, NULL, &PauseTexPos);
}
SDL_RenderPresent(pRenderer);
}
bool KeyPressed(const SDL_Scancode Scancode)
{
return Keys[Scancode];
}
