Return values
The function returns the current mouse wheel position.
Description
The function returns the current mouse wheel position. The mouse wheel can be thought of as a third
mouse axis, which is available as a separate wheel or up/down stick on some mice.
Notes
A window must be opened for the function to have any effect, and glfwPollEvents, glfwWaitEvents or
glfwSwapBuffers must be called before any mouse wheel movements are recorded and reported by
glfwGetMouseWheel.