Graphics Reference
In-Depth Information
Fig. 13.3 Edge loops on the face of this character, shown in green on the right , allow subtle facial
expressions to be animated (Character and render courtesy of Kim Goossens)
13.3.5
Motion Path
A motion path is a curve that has been designated as a guide curve for an animated
object. The curve is given a length in frames, and then the animated object will
traverse the curve in that many frames. Motion paths can be attached to anything,
but they are particularly useful for making smooth camera animation.
13.3.6
Skeletal
Skeletal animation of characters is accomplished with the use of virtual bones con-
nected by joints. The character is then attached to the bones in a process called
skinning , because it involves putting a “skin” on the bones. Once this is done, the
bones can be modifi ed and the vertices of the attached character will move with
them. The problem with skinning is that without careful control, severe distortions
of the character geometry will occur. To alleviate this, animators can adjust the
weight of individual bones relative to clusters of vertices. This allows vertices to
fl ex realistically as the joints are moved and deformed.
To hold the shape of joint objects, modelers must add several edge loops at all
joints (Fig. 13.3 ). The polygons in these areas will stretch, and the textures along
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