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I don't see this behavior on Windows 7, anyway. If I move the mouse and scroll vigorously, I only ever see a y value of 1 or -1 in the mouse wheel event. Can you post a test program that reproduces this?

(In reply to Adam M. from comment #1)
> I don't see this behavior on Windows 7, anyway. If I move the mouse and
> scroll vigorously, I only ever see a y value of 1 or -1 in the mouse wheel
> event. Can you post a test program that reproduces this?

I found that the reason for this problem was because I was trying to access the wheel value (evnt.wheel.y) outside of the while (SDL_PollEvent(&evnt) != 0). I’m guessing then that the SDL_Event wasn’t designed to be used like that? I managed to work around this by simply saving the value of the wheel in a local variable and then accessing it later outside the loop. I apologize for the inconvenience since this was just a user error on my part.

Thank You for your time

No need for apologies. SDL has terrible documentation, and it's often not clear what the best practices are for using it, or whether a particular behavior is correct or not.

That said, this behavior doesn't sound like a quirk of SDL. I don't believe SDL is going to overwrite your event except when you ask it to, although I would only be 90% shocked if that turned out to be the case.

If your code is like:

SDL_Event e;
while(SDL_PollEvent(&e))
{
  // process event
}

Then 'e' will be overwritten on every iteration of the loop, so outside the loop you'll only see the event from the last iteration. SDL_Event is a union, which means that e.wheel, e.motion, e.window, etc. all share the same storage space in memory. So when one is overwritten, they all are. (But even if that were not the case, you should not expect a function that returns a structure like this to preserve any part of it unless it's explicitly documented to do so.) The only case where you can expect to use the mouse wheel information outside the loop is something like this:

SDL_Event e;
while(SDL_PollEvent(&e))
{
  if(e.type == SDL_MOUSEWHEEL) break;
  // other event processing
}
// use e.wheel.x here

(But even then you can't be sure whether it exited the loop because of a MOUSEWHEEL event or because it ran out of events...)