OptionalbounceUse this bounceBox instead of (0, 0, viewport.worldWidth, viewport.worldHeight)
OptionaleaseEase function or name (see http://easings.net/ for supported names)
OptionalfrictionFriction to apply to decelerate if active
Optionalsides"all", "horizontal", "vertical", or combination of "top", "bottom", "right", "left" (e.g., 'top-bottom-right')
OptionaltimeTime in ms to finish bounce
Optionalunderflow(top/bottom/center and left/right/center, or center) where to place world if too small for screen
Options for Bounce.