使用SDL / C ++处理事件的最佳方法是什么

Question

I am using SDL for the view parts of my game project. And I want to handle key press events without interrupting the main thread. So I decided to run an infinite loop in another view thread to catch any events and inform the main thread. However, I am not sure that this is the best since this may cause a workload and decrease the system performace? Is there any better way to do this kind of things? Thanks.

Answer 1

Don't bother with another thread. What's the point?

What does your main thread do? I imagine something like this:

1. Update Logic
2. Render
3. Goto 1

If you receive input after (or during) the update cycle then you have to wait till the next update cycle before you'll see the effects. The same is true during rendering. You might as well just check for input before the update cycle and do it all singlethreaded.

1. Input
2. Update Logic
3. Render
4. Goto 1

Multithreading gains nothing here and just increases complexity.

For some added reading, check out Christer Ericson's blog post about input latency (he's the director of technology for the team that makes God of War).

Answer 2

And I want to handle key press events without interrupting the main thread.

SDL is not inherently an interrupt or event driven framework. IO occurs by reading events off of the event queue by calling SDL_WaitEvent or SDL_PollEvent . This must occur in the " main " thread, the one that called SDL_SetVideoMode .

That's not to say you cannot use multiple threads, and there's good justification for doing so, for instance, it can simplify network communication if it doesn't have to rely on the SDL event loop. If you want the simulation to occur in a separate thread, then it can pass information back and forth through synchronized shared objects. In particular, you can always put events into the SDL event queue safely from any thread.