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Part V: Animation and Rendering Basics

The Bank Amount value sets the depth of the bank, and the Smoothness value determines how smooth the
bank is. The Allow Upside Down option lets the object spin completely about the axis, and the Constant
Velocity option keeps the speed regular. The Loop option returns the object to its original position for the
last frame of the animation, setting up a looping animation sequence. The Relative option lets the object
maintain its current position and does not move the object to the start of the path. From its original posi-
tion, it follows the path from its relative position. At the bottom of the Path Parameters rollout, you can
select the axis to use.
Tutorial: Creating a spaceship flight path
Another way to use splines is to create animation paths. As an example, you use a Line spline to create an
animation path. You can use splines for animation paths in two ways. One way is to create a spline and
have an object follow it using either the Path constraint or the Path Follow Space Warp. The first vertex of
the spline marks the first frame of the animation. The other way is to animate an object and then edit the
Trajectory path.
In this tutorial, you use a simple path and attach it to a spaceship model. Viewpoint Datalabs provided the
spaceship model.
To attach an object to a spline path, follow these steps:
1. Open the Spaceship and asteroids.max file from the Chap 22 directory on the DVD.
This file contains the spaceship model and several asteroid objects.
2. Select Create ➪ Shapes ➪ Line, and click and drag in the Top viewport to create an animation path
that moves the spaceship through the asteroids. Right-click when the path is complete. Then select
the Modify panel, click the Vertex button in the Selection rollout to enable Vertex subobject mode,
and edit several vertices in the Front viewport. Then right-click to exit vertex subobject mode.
3. With the spaceship selected, choose Animation ➪ Constraints ➪ Path Constraint. Then click the
animation path to select it as the path to follow. Select the Follow option in the Path Parameters
rollout, and choose the Y-Axis option.
4. Click the Play Animation button in the Time Controls to see the spaceship follow the path.
Figure 22.3 shows the spaceship as it moves between the asteroids.
Position constraint
You can use the Position constraint to tie the position of an object to the weighted position of several target
objects. For example, you could animate a formation of fighter jets by animating one of the jets and using
Position constraints on all adjacent jets.
The Position constraint menu option lets you select a single target object, enabling you to place the pivot
points of the two objects on top of one another. To add another target object, click the Add Position Target
button in the Position Constraint rollout in the Motion panel. This button enables you to select another tar-
get object in the viewports; the target name appears within the target list in the rollout.
If you select a target name in the target list, you can assign a weight to the target. The constrained object is
positioned close to the object with the higher weighted value. The Weight value provides a way to center
objects between several other objects. The Keep Initial Offset option lets the object stay in its current loca-
tion, but centers it relative to this position.
Figure 22.4 shows a sled positioned between four tree objects using the Position constraint. Notice how the
weight of the downhill tree object is weighted higher than the other targets and the sled is close to it.

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