Graphics Programs Reference
In-Depth Information
Before you can use an SDK, you must create extra attributes and attach them to a
character's top node. These new attributes drive part of the character's animation. The
term
character
is used broadly here. For example, you can set up a vehicle so that an SDK
turns its wheels.
Let's start with a simple SDK relationship between two objects. You'll create a relation-
ship between a ball and a cone. As the ball moves up in the
Y
-axis, the cone spins in the
X
-axis. As the ball descends, the cone spins back. You'll then revisit the hand and set up
an SDK on the skeleton that animates the model.
Creating a Set-Driven Key
To create a simple SDK to make a sphere control the animation of a cone's rotation, follow
these steps:
1. Create a NURBS sphere and a
cone in a new scene. Move the
cone to the side of the sphere,
and lay it on its side, as shown in
Figure 9.58.
2. Select the sphere, and in the
Animation menu, choose Ani-
mate
➔
Set Driven Key
➔
Set. The
Set Driven Key window opens with the nurbsSphere1 object selected in the lower half
of the window (the Driven section). Its attributes are listed on the right, as you can
see in Figure 9.59.
Figure 9.58
lay out a cone
and a sphere.
Figure 9.59
The Set Driven
Key window
3. You want the sphere to drive the animation
of the cone, so you need to switch the sphere
to be the driver and not what's driven. Click
the Load Driver button to list the sphere in the
top half of the window.
4. Select the cone, and click the Load Driven
button to display the cone's attributes in the
bottom half of the window.
5. In the Driver section, select the sphere's
translateY attribute. In the Driven section,
select the cone's RotateX attribute. Click the
Key button to set an SDK that essentially says
that when the sphere is on the ground (
Y
=
0), the cone's
X
rotation is 0 because both
