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Figure 8-7: The Select Parent dialog box indents all child objects under their parent.

The Schematic View (opened with the Graph Editors New Schematic View menu command) presents a graph in which objects are represented by rectangles with their hierarchical links drawn as lines running between them. The Schematic View window is covered in the next chapter.

The Track View (opened with the Graph Editors New Track View menu command) displays lots of scene details in addition to the object hierarchy. In the Track View, you can easily expand and contract the hierarchy to focus on just the section you want to see or select.

Cross-	For more information on using the Track View, see Chapter 33, “Working with the Track View.”
Reference

Working with Linked Objects

If you link some objects together and set some animation keys, and the magical Play button starts sending objects hurtling off into space, chances are good that you have a linked object that you didn’t know about. Understanding object hierarchies and being able to transform those hierarchies are the keys to efficient animation sequences.

All transformations are done about an object’s pivot point. You can move and reorient these pivot points as needed by clicking the Pivot button under the Hierarchy panel.

246 Part II Working with Objects

Several additional settings for controlling links are available under the Hierarchy panel of the Command Panel (the Hierarchy panel tab looks like a mini-organizational chart). Just click the Link Info button. This button opens two rollouts if a linked object is selected. You can use the Locks and Inherit rollouts to limit an object’s transformations and specify the transformations that it inherits.

Cross-	I present more information on object transformations in Chapter 10, “Transforming Objects —
Reference	Translate, Rotate, and Scale.”

Selecting hierarchies

You need to select a hierarchy before you can transform it, and you have several ways to do so. The easiest method is to simply double-click an object. Double-clicking the root object selects the entire hierarchy, and double-clicking an object within the hierarchy selects it and all of its children.

After you select an object in a hierarchy, pressing the Page Up or Page Down keyboard shortcut selects its parent or child objects. For example, if you select the Sun object and press Page Down, all planet objects are selected and the Sun object is deselected. Selecting any of the planet objects and pressing Page Up selects the Sun object.

Linking to dummies

Dummy objects are useful as root objects for controlling the motion of hierarchies. By linking the parent object of a hierarchy to a dummy object, you can control all the objects by moving the dummy.

To create a dummy object, select Create Helpers Dummy, or open the Create panel and click the Helpers category button (this button looks like a small tape measure) and select the Standard category. Within the Object Type rollout is the Dummy button; click it, and then click in the viewport where you want the dummy object to be positioned. Dummy objects look like wireframe box objects in the viewports, but dummy objects are not rendered.

Tutorial: Circling the globe

When you work with complex models with lots of parts, you can control the object more easily if you link it to a Dummy object and then animate the dummy object instead of the entire model. To practice doing this, we create a simple animation of an airplane flying around the globe. To perform this feat, we create a dummy object in the center of a sphere, link the airplane model to it, and rotate the dummy object. This tutorial involves transforming and animating objects, which are covered in later chapters.

Cross-	Rotating objects is covered in Chapter 10, “Transforming Objects — Translate, Rotate, and
Reference	Scale,” and the basics of animation are covered in Chapter 30, “Animation Basics.”

To link and rotate objects using a dummy object, follow these steps:

1.Open the Circling the globe.max file found in the Chap 08 directory on the CD-ROM.

This file includes a transparent wireframe sphere with an airplane model positioned above it. The airplane model was created by Viewpoint Datalabs.

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2.Select Create Helpers Dummy, and then drag in the center of the Sphere to create a Dummy object.

3.Because the dummy objects is inside the sphere, creating the link between the airplane and the dummy object can be difficult. To simplify this process, select and right-click the sphere object, and then select Hide Selection from the pop-up menu.

This hides the sphere so that you can create a link between the airplane and the dummy object.

4.Click the Link button on the main toolbar, and drag a line from the airplane to the dummy object.

5.Click the Auto Key button (or press N) to enable animation key mode, and drag the Time Slider to frame 100. Then click the Select and Rotate button on the main toolbar (or press E), and select the dummy object. Then rotate the dummy object, and notice how the linked airplane also rotates over the surface of the sphere.

6.Select the dummy object, and right click to access the pop-up quadmenu. Then select the Unhide All menu command to make the sphere visible again.

By linking the airplane to a dummy object, you don’t have to worry about moving the airplane’s pivot point to get the correct motion. Figure 8-8 shows a frame from the final scene.

Figure 8-8: With a link to a dummy object, making the airplane circle the globe is easy.

248 Part II Working with Objects

Summary

As scenes become more complex, the name of the game is organization. You can organize objects within the scene in several ways, including grouping, linking, and building hierarchies.

In this chapter, you’ve done the following:

Grouped objects using the Group menu and learned to work with groups

Learned about parent, child, and root relationships

Created a hierarchy of objects using the Link and Unlink features

Viewed links in the viewport

Learned how to create and use dummy objects

In the next chapter, you learn how to use an interface that helps as you organize scenes of objects — the Schematic View window.