This one-screen prototype demonstrates some of Proto.io animation functionality.

If you need to get the Y position of a vertically scrolling container, create a text box. Then on the container scroll trigger, set a variable that evaluates the numerical callback value from the event (Y position). Then add a callback that changes the text property of the text box by reading from the variable.

This is an example of a Navigation Bar that disappears on any downward scroll and re-appears on on any upward scroll.