Facial Animation Setup - Game Character Development with Maya - page 855

6. Select all the coordinates and set them to 0 . This resets the selected vertices back
to their default positions ( Figure 13.36c ) .
7. Select the central vertices ( Figure 13.36d ), and in the Channel Box set them to be
half of their current values.
Why are we setting the central vertices to half? Each blend shape works relatively;
that is, the vertex positions are added to any that are already applied. So if the left
eyebrow and right eyebrow shapes fully affected the central vertices on the head,
when both shapes were applied these vertices would move double the distance.
So when we set vertices that may need to share their values to move half the
amount for each eyebrow, it means that when both are applied at the same time,
the central vertices won't move too far up. They'll wind up where you actually
want them to be.
8. On the RightBrowUp model, reset the vertices on its left and center ( Figure
13.36e ) , just as you did for LeftBrowUp.
The technique you've just used is a quick and easy way to get two shapes out of one; plus,
you will know that each side will be the same. It may be that you don't want the face to be
symmetrical, which is fine, but this way you get a good starting point from which you can
tweak later.
Go ahead and create the rest of the face shapes needed, by simply duplicating the main
head and editing the vertices. You should have the following:
Both the left and right eyebrows, lowered.
Both individual eyelids opening wider and closing.
The remaining facial shapes L, MPB, FV, Ooo, Smile, and Frown.
Tip
For the eyelids, you will need to use the shape of the eyes as a guide, so
keep the duplicated head in its default position until you are happy with
the eyelid shape.
You can see all of these shapes in Figure 13.38 . These represent a good initial group of
face shapes for a character. If your budget allows, you can add more to get more refined
manipulation of the face.