slideIn
Slides the overlay from from to where it was authored over duration, counted from its first drawn frame.
The travel is linear and the offset is a fraction of the frame, so a start of -0.2f on x brings the overlay in from a fifth of the frame width off its authored position. A duration of zero or less draws the overlay at its authored position from its first frame.
Return
An animation sliding the overlay in.
Parameters
from
Where the overlay starts, relative to where it was authored.
duration
How long the overlay takes to arrive.