SDL hint SDL_HINT_RENDER_VSYNC

SDL Development
1

Hi! I’m trying to set hints in my options screen. Stucked in vsync.

Core::Core() : frameTime(0), MIN_FRAME_TIME(3.333333333333333f), w(0), h(0)
{
    window.Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_AUDIO);

    window.createWindow("Platformer", Config::SCREEN_WIDTH, Config::SCREEN_HEIGHT, 
SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);

   renderer = SDL_CreateRenderer(window.getWindow(), -1, SDL_RENDERER_ACCELERATED);

    event = new SDL_Event;
    Initialize();
}

void Core::MainLoop()
{
lFPSTime = SDL_GetTicks();
while (!quit && event->type != SDL_QUIT)
 {            
                //tried here
                //SDL_SetHint(SDL_HINT_RENDER_VSYNC, "1");
	    SDL_GetWindowSize(window.getWindow(), &w, &h);

	    frameTime = SDL_GetTicks();

	    SDL_PollEvent(event);

	    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
	    SDL_RenderClear(renderer);

	    std::cout << "FPS: " + std::to_string(iNumOfFPS) << std::endl;
	    if (SDL_GetTicks() - 1000 >= lFPSTime) 
                {
		     lFPSTime = SDL_GetTicks();
		     iNumOfFPS = iFPS;
		     iFPS = 0;
	     }

	     ++iFPS;

                 //tried here
                 SDL_SetHint(SDL_HINT_RENDER_VSYNC, "1");

	     Input();

	     Update();

	     Draw();

	     SDL_RenderPresent(renderer);

	     if (SDL_GetTicks() - frameTime < MIN_FRAME_TIME) 
	     {
		     SDL_Delay(MIN_FRAME_TIME - (SDL_GetTicks() - frameTime));
	     }

	     SDL_SetHint(SDL_HINT_RENDER_VSYNC, "1");
    }

    SDL_FreeCursor(ScreenManager::GetInstance().GetCursor());
}

I know that this fps timer isn’t so good. Just want to test out hints.

So what this code doing. MIN_FRAME_TIME is set to 3.3333333 so it means it’s going to be ~300 fps. In mainLoop I set vsync to 1, so it should set fps to 144, because my monitor is 144hz. Unfortunately timer still shows 300 FPS. The only way to set vsync is set

 renderer = SDL_CreateRenderer(window.getWindow(), -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);

but this way I cannot set it via options screen.

2

I doubt the hint will work like that.

You could probably delete the renderer and create a new one, but I haven’t used the sdl rendering api much so I don’t know if there is a better way (when using opengl you can set vsync on and off explicitly).

3

https://wiki.libsdl.org/SDL_HINT_RENDER_VSYNC?highlight=(\bCategoryDefine\b)|(CategoryHints)

SDL_HINT_RENDER_VSYNC overrides the SDL_RENDERER_PRESENTVSYNC flag in SDL_CreateRenderer().