Originally posted by Disney2002
If that is what happens, the answer is simple.
If you look at the film without your glasses you will notice that objects that do not appear in 3D are clear, while those which are in 3D are blurry. In fact, the closer the 3D image appears to be, the more blurry the image without glasses.
This is because the 3D effect is generated by further skewing the pictures seen by your right and left eye. This is the way depth perception works in real life actually.
Try holding you finger out in front of your face as far as your are can stretch. Look at it with one eye -- then the other. Notice that the finger seems to change place based on which eye you look with.
Now hold your finger about 6 inches from your face and repeat the process. Notice this time that the finger move A LOT compared to the background.
By simulating this in film (and then correct the image for each eye using the polarized lenses), the 3D effect is created.
In order to have images appear as if they are being sucked into the screen, the film simply starts looking incredibly blurry, and slowly moves to look in focus (if you weren't wearing your glasses).
Nothing difficult at all!
Hope the explanation of 3D helped!