It’s possible to configure scroll wheels to reverse their normal direction (such as in System Preferences in OS X). I’m trying to determine what standard is used as far as the values that GLFW returns in the scroll wheel callback function, specifically whether they are the raw values from the scroll wheel or if they may be reversed, whether they may be reversed in only one direction (e.g., Y not X), and if the behavior is consistent across platforms.
I looked in the documentation and the FAQ, but if it’s there then I must have missed it.
According to the C code on Windows the inputs are:
X: +ve value means the wheel was scrolled to the left.
Y: +ve value means the wheel was scrolled forwards, away from the user.
There is a note in the code for the Y axis stating that this is inverted from the OS default to maintain consistency with the OSX and X11 code, and I would assume the same for the Y axis without other information (indeed they should be the same, and I’ve confirmed this with the OS X implementation and documentation).
Further information can be gleaned from the source: there is no code for inverting directions in GLFW, this is likely handled by the OS or mouse driverf itself if available.
This should probably be added to the documentation - would you like to file the request on GLFW’s Github issue list?? If not I can file it.