glfwPollEvents exits function

support
1

anonymous wrote on Wednesday, September 19, 2012:

I recently noticed that a call to glfwPollEvents (or glfwWaitEvents)
immediately exits the containing function. Consider this example:

bool event_loop(void) {
  glfwPollEvents();
  update(); // Never gets called...
  return true;
}
int main() {
  // Initialization...
  while(event_loop()) {
    render();
    glfwSwapBuffers();
  }
  // Termination...
}

Now when I structure my code like this the window freezes because the update
and render functions are never called. I’m fairly new to GLFW, so my question
is if this is the intended behavior or there is something wrong with my code?
I’m using GLFW from the SVN trunk as a static library under Visual Studio
2012.

2

elmindreda wrote on Wednesday, September 19, 2012:

It’s not intended behaviour and shouldn’t even be possible behaviour.

3

elmindreda wrote on Wednesday, September 19, 2012:

The problem is likely in your code or the compiler settings.

4

anonymous wrote on Wednesday, September 19, 2012:

It was a bug in my code. The problem was related to my callback settings. I
registered a callback with glfwSetWindowRefreshCallback which also called
glfwSwapBuffers. Every time I polled events the refresh callback got called
and therefore creating an infinite loop. I guess I have to restructure my code
a bit…

One more question: In case the refresh callback calls glfwSwapBuffers is it
recommended to disable GLFW_AUTO_POLL_EVENTS?

Thanks alot for your help!

5

anonymous wrote on Wednesday, September 19, 2012:

Just found the answer in the docs:

When GLFW_AUTO_POLL_EVENTS is disabled, calling glfwSwapBuffers will not
result in a call to glfwPollEvents. This can be useful if for example
glfwSwapBuffers needs to be called from within a callback function, since
calling glfwPollEvents from a callback function is not allowed.

Thanks again!

6

elmindreda wrote on Wednesday, September 19, 2012:

Glad it works now and thank you for the detailed follow-up!