3ds Max 2012 Bible - Kelly L. Murdock [259]
To make an airplane follow a looping path, follow these steps:
1. Open the Looping airplane.max file from the Chap 21 directory on the CD.
This file includes a simple looping spline path and an airplane created by Viewpoint Datalabs.
2. With the airplane selected, open the Motion panel and click the Trajectories button. Then click the Convert From button in the Trajectories rollout, and select the path in the Front viewport.
3. If you drag the Time Slider, you'll notice that the plane moves along the path, but it doesn't rotate with the path. To fix this, click the Key Mode Toggle button in the Time Controls to easily move from key to key. Click the Key Filters button, select only Rotation, and then click the Set Key button (or press the ' key) to enter Set Key mode.
4. Before moving the Time Slider, click the Set Keys button to create a rotation key at frame 0. Then click the Select and Rotate button, click the Next Key button, rotate the plane in the Front viewport to match the path, and click the large Set Keys button (or press the K key) to create a rotation key. Click the Next Key button to move to the next key, and repeat this step until rotation keys have been set for the entire path.
5. Drag the Time Slider, and watch the airplane circle about the loop.
Cross-Reference
Max provides an easier way to make the plane follow the path using the Path constraint. To learn more about constraints, see Chapter 22, “Animating with Constraints and Simple Controllers.” •
Figure 21.9 shows the plane's trajectory.
FIGURE 21.9
When you use a spline path, the position keys are automatically set for this plane.
Using the Follow/Bank utility
When an object travels along a path that defines its trajectory, it maintains its same orientation without rotating. Imagine a roller coaster car; it rotates and banks as it moves around the track. This rotation and banking motion can be added to an object following a path using the Follow/Bank utility. You can access this utility by opening the Utilities panel and clicking the More button. Double-click the Follow/Bank utility to load it into the Utilities panel.
Caution
The Follow/Bank utility aligns the local X-axis of the object with the local Z-axis of the spline when the utility is applied, so you need to correctly orient the object's pivot point before applying the utility. If you don't, the object will be aligned at right angles to the path. •
The Follow/Bank utility lets you enable a Bank option and set its Amount and Smoothness. Another option allows the object to turn upside down (not recommended for a traditional roller coaster car). Click the Apply Follow button to add the keys to cause the object to follow and bank. The Samples section determines how many keys are created.
Using Ghosting
As you're trying to animate objects, using the ghosting feature can be very helpful. This feature displays a copy of the object being animated before and after its current position. To enable ghosting, choose Views⇒Show Ghosting. The Show Ghosting command displays the position of the selected object in the previous several frames, the next several frames, or both. This command uses the options set in the Preference Settings dialog box. Access this dialog box by choosing Customize⇒Preferences. In the Viewports panel of this dialog box is a Ghosting section.
You use this Ghosting section to set how many ghosted objects are to appear; whether the ghosted objects appear before, after, or both before and after the current frame; and whether frame numbers should be shown. You can also specify every Nth frame to be displayed. You also have an option to display the ghost object in wireframe (it is displayed as shaded if this option is not enabled) and an option to Show Frame Numbers. Objects before the current frame are colored yellow, and objects after are colored light blue.
Figure 21.10 shows a lion toy object that is animated