Aspects herein are directed to an article of apparel having a vent opening formed by overlapping the edges of a first panel and a second panel. A plurality of discrete overlay film structures are applied to the second panel adjacent to the vent opening. When the article of apparel is exposed to an external stimulus, the film structures undergo a reversible increase in dimension in at least the z-direction which cause the second panel of material to undergo a reversible decrease in dimension in the direction of a longitudinal axis of the vent opening thereby causing the vent opening to dynamically transition from a closed state to an open state.