If it were me, I would duplicate your book layer and place it on top of the comp stack. Then I would mask the page that will constrain your silhouette animation. You may have to adjust your mask frame by frame, but it shouldn’t be to difficult as everything should be hard/straight lines. When that is done, place the “silhouette animation” below your masked page and change the it’s track matte(F4 will toggles between track mattes and layer switches) to “alpha matte”. Now the silhouette should be constrained to the page.
Johnny Cuevas, Editor
ThinkCK
“I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work.”
—THOMAS EDISON on inventing the light bulb.