Animating Depth: Tweening Movement - Flash 3D: Animation, Interactivity, and Games - page 77

In order for the parallax scrolling to appear as continuous movement, both ends of the
scrolling graphic must match. You accomplished this by duplicating the tree in the same
position and dragging it to both ends of the Stage (Figure 3.34).
Figure 3.34 Both ends must match for the parallax scrolling to work.
Step 6: Create a forest
Two trees are boring. We want to create a forest of trees. Since a tree is still copied to
the computer's clipboard, paste in several more trees. Fill in the space between each
end tree. Position these trees wherever you want (Figure 3.35).
Figure 3.35 Pasting several copies of trees and positioning them
Step 7: Double the width of the forest (Part 1)
You completed one requirement for the parallax scroll to work—both ends must match.
The second requirement is that the scrolling graphic must be at least twice the width