SDL_GetTicks() accuracy below the millisecond level

Question

I program currently something with SDL2. All works fine, but I have a problem with the SDL_GetTicks() method. Normally it should return the total application ti

Answer 1

Well, of course, you need to actually wait until >=1ms has passed before updating your last tick count

void Application::Update()
{
    Uint32  current_time = SDL_GetTicks();
    Uint32  delta_time = current_time - last_update_time;

    SDL_Event event;
    while(SDL_PollEvent(&event))
    {
        switch(event.type)
        {
            case SDL_QUIT:
            {
                should_close = true;
            }
            break;

            default:
                break;
        }
    }

    if (delta_time >= 1)
    {
        // Update game objects with delta_time

        last_update_time = current_time;
    }   
}

Answer 2

You cannot use SDL_GetTicks() if you want higher precision but there are many other alternatives. If you want to be platform independant you need to be careful though, but here is a portable C++11 example that will get you started:

#include <iostream>
#include <chrono>
typedef std::chrono::high_resolution_clock Clock;

int main()
{
    auto t1 = Clock::now();
    auto t2 = Clock::now();
    std::cout << "Delta t2-t1: " 
              << std::chrono::duration_cast<std::chrono::nanoseconds>(t2 - t1).count()
              << " nanoseconds" << std::endl;
}

Running this on ideone.com gave me:

Delta t2-t1: 282 nanoseconds