Let's get to the basics of how Maya is laid out (See Figure 2.1). Running across the top of the screen, right under the application's title bar, are the UI elements: Main Menu bar, the Status line, and the Shelf. On a Macintosh system running OS X, note that the Main Menu bar actually runs at the very top of the screen, above the application's title bar.

To the left of the screen, running vertically is the Tool Box, offering quick-view selections. Across from the Tool Box are the Channel Box/Layer Editor and sometimes the Attribute Editor (not displayed in Figure 2.1). Running horizontally at the bottom of the screen (from the top down) are the Time Slider, the Range Slider, the Character Set menu, the Auto Keyframe button, and the Animation Preferences button. In the middle of all these elements is the workspace, which is host to your panels (or Scene windows) and their menu options, (known as view s or viewports in some other 3D packages). This is where most of your focus will be; this is where you create and manipulate your 3D objects.

Figure 2.1. The initial Maya screen

If you see a single, large view panel (most likely named persp), click inside it with the mouse to activate the panel and then press the spacebar to return to the four-panel layout shown in Figure 2.1. A panel is active when you see a blue borderline around it.

Maya is case sensitive in that it distinguishes between lowercase and uppercase letters. The conventions of this book will always print an uppercase letter to denote which key you must press, but will specify "Shift + the letter" when you must press the uppercase of that key. In other words, when we ask you to press the E key, for example, you should simply press the E key on your keyboard, lowercase. When an uppercase letter is called for, the book calls you to press Shift+E, requiring you to enter the uppercase letter E into Maya.

Maya requires the use of a three-button mouse, even on a Macintosh system. The clickable scroll wheel found on most mice can be used as the third button by pressing down to click with the wheel. The scroll wheel also lets you zoom into or out of a view panel.

In Maya, holding the Alt key on a PC or the Option key on a Mac along with the appropriate button (listed below) allows you to move in the view panel. The left mouse button (LMB) acts as the primary selection button and allows you to orbit around objects when used with the Alt key. The right mouse button (RMB) activates numerous shortcut menus and lets you zoom when used with the Alt key. The middle mouse button (MMB) used with the Alt key lets you move within the Maya interface panels, and the mouse's wheel can be used to zoom in and out as well.

Selecting objects in a view panel is as easy as clicking on them. If the object is displayed in Wireframe mode, its wireframe will turn green while it is selected. If the object is displayed in a Shaded mode, the object's wireframe will appear around the object. Shaded mode is a way of seeing your objects in the view panel with a basic surface, as opposed to a wireframe that you can see through. You'll see this as we do the following exercise.

To select multiple objects, simply hold the Shift key as you click on objects to add to your current selection. The previous selection's wireframe will turn white and the new selection will now be green. If you Ctrl+LMB (i.e., press the Ctrl key and click) on an active object, you will deselect it. To clear all of your current selections, click anywhere in the empty areas of the view panel.

When you select an object and enable one of the transformation tools (tools to allow you to move, rotate, or scale an object), you will see a Manipulator appear at or around the selected object. Figure 2.2 shows the three distinct and most common Manipulators for all objects in Maya: Move, Rotate, and Scale as well as the Universal Manipulator. You use these Manipulators to adjust attributes of the objects visually and in real time.

Figure 2.2. The Maya Manipulators

To activate a Transform tool, select an object and then click one of the Transform Tool icons from the Tool Box, shown in Figure 2.3.

Figure 2.3. The Transform tools in the Tool Box

Try This Let's put some of this into action, shall we?

Choose Create → NURBS Primitives → Sphere. Drag in a view panel anywhere on its grid to create a wireframe sphere, and then size it to your liking. In one of the view panels, press the 5 key on your keyboard, and the display of the sphere will become solid gray, as opposed to open wireframe. This is called Shaded mode. Press the 4 key to return to Wireframe mode.

With the sphere selected, select the Move tool

Red is for the X-axis, green is for the Y-axis, and blue is for the Z-axis. Cyan is for free movement in both axes of the active panel view.

Clicking any one of the three arrows lets you move the object only on that particular axis. The square in the middle of the Manipulator lets you move the object freely about the plane of the view panel, regardless of the axis. When you select a Manipulator handle for movement, it turns yellow. The Free Movement box in the center then turns back to its regular color, cyan.

Next, select the Rotate tool

Now try selecting the Scale tool

Try selecting the Universal Manipulator

Go ahead and click around the interface some more. Create more primitive objects and tool around a bit. Move around the view panels and see how it feels. Give the tires a good kick. Enough chatting—let's jump into the Solar System project.

The first thing we're going to do is create the Sun and the planets. Follow these steps:

Creating the Planets

Next, you will create the primitive spheres you will be using for the planets. Leave Interactive Creation off, and follow these steps:

1. Create a NURBS sphere for Mercury and name it Mercury, just as you did before by choosing Create → NURBS Primitives → Sphere. A new sphere appears at the origin. Click its name in the Channel box, and change it to Mercury.

2. Choose the Move tool from the Tool Box to activate the Move Manipulator, and move Mercury a few grid units away from the Sun in the positive X direction. (Click the red arrow and drag it to the right.) Leave about two grid units between Mercury and the Sun.

3. Because Mercury is the second smallest planet and is tiny compared to the Sun, scale it down to 1/20 the size of the Sun, or type in 0.2 in all three axes of scale if you choose to enter the values manually in the Channel box.

4. Repeat steps 1 through 3 to create the rest of the planets and line them up, placing each one farther out along the X-axis. Be sure to keep about two grid units of space between each of them. Scale each one proportionally as follows:

Venus	0.5
Earth	0.5
Mars	0.4
Jupiter	1.0
Saturn	0.9
Uranus	0.7
Neptune	0.7
Pluto	0.15

These proportions are not exactly the same as those found in the real solar system, but they will do nicely here. Figure 2.9 shows how your solar system should look now.

Figure 2.9. All the NURBS spheres are lined up in place (top view).

Note

No, Pluto is not actually a planet, but for nostalgia's sake, we'll include it here in our solar system.

Using Snaps

Now is the perfect time to start using snaps. Some common snap icons are shown in Table 2.1. Snap icons are explained in greater depth in the next chapter. These icons run across the top of the UI just below the Main Menu bar, as shown here.

Table 2.1. Snap Icons

Icon	Name	Description
	Snap to Grids	Snaps objects to intersections of the view's grid
	Snap to Curves	Snaps objects along a curve
	Snap to Points	Snaps objects to object points such as CVs or vertices
	Snap to View Planes	Snaps objects to view planes

You use snaps to snap objects into place with precision, by placing them by their pivot points directly onto grid points, onto other object pivots, onto curve points, and so on. Here you will reposition all the planets slightly to center them on the nearest grid line intersection. To do so, follow these steps:

1. Select the first planet, Mercury; choose the Move tool from the Tool Box; and toggle on grid snaps by clicking the Snap to Grids icon

   

2. The center of the Move Manipulator turns from a square to a circle, signaling that some form of snapping is active. Grab the Manipulator in the middle by this circle, and move it slightly to the left or right to snap it onto the closest grid intersection on the X-axis.

3. Select the remaining planets, and snap them all to the closest grid intersection on the X-axis, making sure to keep about two grid spaces between each of them. Because the Sun was created at the origin and you haven't moved it, you don't need to snap it onto an intersection.

SAVING MULTIPLE VERSIONS OF YOUR WORK AND INCREMENTAL SAVING

As you're working on a project, you may want to save multiple versions of your files at various stages of completion. When working in the professional world, you'll find that clients and art directors often reconsider animations you've created, sometimes, it seems, just to make you crazy. So it's always good to keep as many versions of an animation as you can. Scene files are reasonably small, and hard disk space is inexpensive. Just keep your Scene folder organized well—for example, by keeping older versions of scenes in separate subfolders—and you should have no problems.

Maya's Incremental Save feature makes a backup of your scene file every time you save your scene. To enable it, choose File → Save Scene

The scene files for the projects in this book are provided on the accompanying CD to give you a reference point for the major stages of each project. These files use a slightly different naming system than the names generated by Incremental Save (for example, the file on the CD is planets_v1.mb instead of planets_001.mb), so there is no risk of files overwriting each other.

For important real-world projects, you might decide to supplement the Incremental Save backups by using Save Scene As to create named files manually, perhaps following a similar naming system with a version number appended, at the stages where you've made significant changes. Whether you do this or use Incremental Save, it's a good idea to keep written notes about the differences in each version of a scene file so that whenever you make a significant change to a file, you have a record of your work.

If you prefer to name files manually, be sure to use an underscore (_) between the filename and version number instead of a space. Using spaces in your filenames can create problems with the software and operating system, especially when you're rendering out a scene.

Making Saturn's Ring

Now create the ring for Saturn. To do so, follow these steps:

1. Choose Create → NURBS Primitives → Torus to get a donut shape placed at the origin. Remember, Interactive Creation is turned off. You can also try creating the torus with the Interactive Creation option. In that case, click and drag the mouse to create the donut shape as you prefer. Once you have a ring, use the Move tool to snap it to the same grid intersection as Saturn. This will ensure that both the planet and its ring are on the same pivot point and share the same center.

2. Select the torus shape you've created, and name it Ring (if you haven't already done so) in the Channel box.

3. While the torus shape is still selected in the top view, press the spacebar to display the four-panel layout. Place the mouse cursor in the persp view and press spacebar to maximize the Perspective window.

4. Press the F key to focus the perspective display on the ring, and on Saturn as well. Pressing F will center and zoom in the panel on just the selected object(s).

5. Press 5 to get into Shaded mode and, with the torus selected, press 3 to increase the resolution display for the ring. Display resolutions are achieved by pressing the 1, 2, or 3 keys and are further explained in the next chapter. Pressing 3 will give you the smoothest view of the torus in the view panels. That's a good thing.

6. From the Tool box, select the Scale tool, and scale the torus down to 0 or close to 0 in the Y-axis (the torus' height in this case) to flatten it down.

   You'll notice that the ring is too fat and is cutting into the planet. You need to edit the attributes of the ring to increase the inside radius of the donut shape and create a gap between the planet and the ring.

7. Press Ctrl+A (Ctrl+A will also work on a Mac) to open the Attribute Editor, and then click the makeNurbTorus1 tab to select its creation node. (See Figure 2.10.)

8. Increase the Radius attribute to about 1.5, and decrease the Height Ratio attribute to about 0.25 to get the desired effect.

Now all your planets are complete, and you can move on to the moons.

Note

Changing the original attributes or parameters of an object, as you've just done with Saturn's ring, is often referred to as parametric modeling.

Figure 2.10. Changing the creation attributes of the NURBS torus in the Attribute Editor

Now save your work, unless you like to live on the edge. Saving frequently is a critical habit to develop. Power failures and other unforeseen circumstances (such as your pet jumping onto your keyboard) may not happen often, but they do happen, and usually just at the wrong time. (As mentioned in the sidebar "Saving Multiple Versions of Your Work and Incremental Saving," Maya's Incremental Save feature makes it easy to maintain backups of your work.) Because you created this as a new project, the Save File window will direct you to the Scenes folder of that project. Save your scene as planets in the .mb (Maya Binary) format. (If you're working in Maya PLE, you can only save your files as .mp files, which may not be compatible with full versions of Maya 2009. Maya PLE saves scenes as .mp files simply to differentiate them from full Maya-version saved files.)

The file Planets_v1.mb in the Scenes folder of the Solar_System project on the CD shows what the scene should look like at this point.

For the planets with moons, create a new NURBS sphere for each moon. For simplicity's sake, create a maximum of only two moons for any planet. However, feel free to make all the moons for all the planets once you get a handle on this exercise.

The first moon will be the Earth's. Use the top view to follow these steps:

Figure 2.11. The planets and moons in position in perspective view

To help distinguish one gray planet from another, attach simple shaders to each of the planets to give them color. You can easily take care of this task using the Hypershade window. Follow these steps:

Figure 2.12. The Hypershade window

Again, keeping a well-named and organized scene is critical to a smooth animation experience. It's so much more of a chore to root through dozens of unnamed nodes to find the one you want. When you've finished naming all the material nodes, save your work.

Once you've created the shaders, you can assign the appropriate colors to each of them according to the planet they represent.

Figure 2.16. The shaded planets in perspective view

Now that you're done, you're ready to animate. Just save this file and, if you've enabled Incremental Save as recommended earlier, your file won't be replaced with subsequent saves. This way, if you get lost in your animation and need to start fresh, you won't have to re-create everything from scratch. You can just return to a previous version of the file and start your animation over.

To begin this phase of the project, load the file Planets_v2.mb in the Scenes folder of the Solar_System project on the CD to your hard drive, or continue with your own scene file.

The animation you'll be doing for the orbits is straightforward. You will rotate the planets around their own axes for their self-rotation, then you'll animate the moons around the planets for their lunar orbits, and finally you'll make the planets and their moons orbit the Sun.

The premise of this exercise deals with hierarchy and pivot points. A pivot point is an object's center of balance of sorts. Every object or node that is created in Maya has a pivot point set at the origin. Because most objects, such as the spheres you created for the planets, will appear at the origin upon creation, their pivot points are automatically centered.

Once you move an object, as you have done to position the planets and moons, the pivot point moves with it. Therefore, all your planets' and moons' pivot points will already be correctly positioned at the center of each planet and moon.

Now you need to set up your scene file's animation settings:

At its core, Maya relies on packets of information called nodes, and each node carries with it a group of attributes that in combination define an object. These attributes can be spatial coordinates, geometric descriptors, color values, and so on. Taken together, an object's attributes define it and how it animates. You can define, animate, and interconnect any or all of these attributes individually or in concert, which gives you amazing control over a scene.

When you're beginning to work with a robust program, the learning curve occasionally spikes. With Maya, these spikes typically involve nodes and their interconnections. Although the interface automates much of the node creation and relationship process, the sooner you are exposed to the implications of the node level of objects, the easier it will be for you to overcome the typical learning curve. Even though you may not actively see that you're making root-level connections between nodes and attributes, that is exactly what you are doing every time you click a command.

Nodes that define the shape of a surface or a primitive are called creation nodes or shape nodes. These nodes carry the information that defines how that object is created. For example, a sphere's creation node has an attribute for its radius. Changing that attribute changes the radius of the sphere at its base level. Shape nodes are low on the hierarchy chain and are always child nodes of transform nodes. The sphere listens to its creation node attributes first and then moves down the chain to its other nodes' attributes (such as position, rotation, or scale).

Note

Not all primitives are created with shape nodes, so changes at the creation level may not be possible on certain objects; some objects are created without a creation node. When you create a new primitive or an object, make sure the History button (

The most visible and used nodes are the transform nodes, also known as DAG nodes. These nodes contain all the transformation attributes for an object or a group of objects below it. Transformations are the values for translation (position), rotation, and scale. These nodes also hold hierarchy information on any other children or parent nodes to which they are attached. When you move or scale an object, you adjust attributes in this node.

Try This As an example of working with transform nodes, you can create a sphere and see what happens in the Attribute Editor as you adjust its position and size. Follow these steps in a new Maya scene:

A parent node is simply a node that passes its transformations down the hierarchy chain to its children. A child node inherits the transforms of all the parents above it. So by using hierarchies for the Solar System exercise, you will create a nested hierarchy of parents and children to animate the orbital rotation of the nine planets and some of their moons.

By creating parent-child relationships, you can easily animate the orbit of a moon around a planet while the planet orbits the Sun. With the proper hierarchy, the animation of the planet orbiting the Sun automatically translates into the moon. In effect, the planet takes the moon with it as it goes around the Sun.

Child nodes have their own transformations that can be coupled with any inherited transforms from their parent, and these transformations affect them and any of their children down the line.

The rotation of one of the planets around the Sun takes into account its moons, but those moons can have their own animation to spin themselves around their planets. You are about to experience this first hand as you continue the Solar System exercise. The more you hear about these concepts in different contexts, the easier they will be to master.

Figure 2.20 features the Outliner and Hypergraph views with a simple hierarchy of objects for your reference. The Outliner and Hypergraph show you the objects in your scene in an outline and flowchart format, respectively. Both of these windows allow you to access the different levels of nodes (the hierarchy) in a scene and are discussed further in Chapter 3.

A top parent node called group1 holds its children nurbsCone1, nurbsSphere3, and the nested group node group2. The node group2 is the parent node of nurbsSphere2 and nurbsSphere1.

Figure 2.20. A simple hierarchy in both the Outliner and Hypergraph windows

Load up your scene from where you last saved it. When we left off, we had created the self-rotation animation for Mercury and were about to create a second pivot point for the planet to orbit around the Sun by creating a new parent node for the Mercury sphere.

To create a new pivot point by making a new parent node, follow these steps:

Does that make good sense? You will have the chance to do this a few more times as you animate the other planets and their moons. However, if you still find yourself a little fuzzy on this concept (which is perfectly normal), repeat the steps to animate Mercury in a new scene file if need be. One down, eight to go.

For your next planet, Venus, follow the same procedure as for Mercury's self-rotation and animate it so that it rotates about itself. Then create a new pivot point (placed by default at the origin) by grouping it to itself to create a new parent node for that sphere, and call the new parent node Venus_Orbit. Lastly, animate Venus_Orbit to rotate around the Sun just as you did with Mercury_Orbit in the previous steps.

Now you need to animate the third planet, the Earth, in much the same way, except that this time there will be the added complication of a moon. In addition, instead of choosing Animate → Set Key to set your keyframes, you'll use the keyboard hot key S. (The Earth? Hey, I can see my house from here!)

To animate Earth and the moon, follow these steps:

This time, however, you need the pivot point to be at the center of Earth and not at the center of the Sun object, where it is currently. Follow these steps:

Figure 2.23. Moving the Moon's pivot point to the center of Earth

Auto Keyframe

You can also use the Auto Keyframe feature when animating the planets and moons. Auto Keyframe automatically sets a keyframe for any attribute that changes from a previously set keyframe. For example, an initial keyframe for an attribute such as Y-Axis Rotation needs to be set at some point in the animation. The next time the Y-Axis Rotation is changed, Maya will set a keyframe at the current frame automatically.

To turn on Auto Keyframe, click the Auto Keyframe icon (

To use Auto Keyframe to animate Mars's moon orbiting Mars, follow these steps:

1. Turn on Auto Keyframe.

2. Start at frame 1. Select Mars's moon and set a keyframe for its Y-axis orbit by highlighting Rotate Y in the Channel box and pressing S.

3. Go to frame 240. Rotate the moon around Mars several times in a direction of your choosing. Maya will automatically set a frame for Y rotation at frame 240. Save your file.

The Outliner is an outline format listing of all the objects and nodes in your scene. For an in depth look at the Outliner, see Chapter 3. For now, let's look at how to use the Outliner to illustrate the hierarchies for the planets and moons. When all is good and proper, the Outliner should look like Figure 2.24. Choose Window → Outliner to open the Outliner window and take a peek at what you have. If you haven't yet properly named everything, including the moons, take this opportunity to do so by double-clicking on a name in the Outliner and entering a new name.

Figure 2.24. The Outliner view of the planet hierarchies

Let's take a look at the planet Mars and its layout in the Outliner to understand the hierarchy for all the planets better. All the other planets should be laid out exactly like Mars (except for the planets that have just one or no moons).

At the bottom of the hierarchy are Mars's two moons, mars_moon and mars_moon2. Each of those moons is spinning on its own pivot point. You grouped each moon to itself, created the mars_moon_orbit and mars_moon2_orbit nodes, and you placed their pivot points at the center of Mars to animate their orbits around Mars.

Mars is spinning on its own pivot point, but it needed another pivot point to be able to orbit the Sun. Because you needed to make the moons go with it around the Sun, you selected Mars, mars_moon_orbit, and mars_moon2_orbit (the top nodes of the moons that circle the planet Mars) and grouped them all together, placing that pivot point at the center of the Sun. You called this node Mars_Orbit. This is the parent node because it is the topmost node for this group. Wherever this parent node goes, the child nodes that are under it will follow.

Hierarchies such as this are a cornerstone of Maya animation. It is imperative that you're comfortable with how they work and how to work with them. If you find yourself scratching your head even just a little bit, try the exercise again. A proper foundation is critical. Remember, this learning 3D thing is not easy, but patience and repetition help a lot.

Correcting Hierarchy Problems Using the Outliner

One of the most common problems you will run into with this project is a planet rotating around the Sun without its moon. To illustrate how to fix it using the Outliner, as opposed to undoing and redoing it as suggested earlier, the following steps will force you to make this error with Pluto. Usually people learn more from mistakes than from doing things correctly.

Go to Pluto, start the same animation procedure as outlined earlier, and then follow these steps to force an error:

1. Create Pluto's own self-rotation by spinning it around itself and keyframing as before.

2. Do the same for Pluto's moon's rotation.

3. Group the moon to itself and grid-snap the pivot point at the center of Pluto to create the moon's orbit of Pluto.

   Once Pluto's moon (pluto_moon) is orbiting Pluto, you're ready to group the moon's orbit and Pluto together to create an orbit of the Sun for both.

4. Here is where you make your mistake. In Object mode, select the sphere for Pluto's moon and select the sphere for Pluto. Your error is that you are remaining in Object mode instead of switching to Hierarchy mode.

5. Choose Edit → Group to group them together, and call that new node Pluto_Orbit (following the naming convention we used for the others).

6. Animate Pluto_Orbit rotating around the Sun.

7. Play back the animation.

Figure 2.25. Pluto's incorrect hierarchy

Figure 2.26. Regrouping objects in the Outliner

Notice that the moon is no longer orbiting the planet. This is because you didn't include pluto_moon_orbit in your group Pluto_Orbit. The animation of the moon going around Pluto is stored in that node, and because it is no longer attached to Pluto_Orbit, there's no moon orbit of Pluto.

Figure 2.25 shows the hierarchy of Pluto and how it's different from that of the other planets: The moon's orbit node has been left out of the group. (Earth has been expanded as a contrasting example.)

Using the Outliner, you can easily fix this problem. Place the pluto_moon_orbit node under the Pluto_Orbit node. Go to frame 1 of the animation, grab the pluto_moon_orbit node in the Outliner, and use the middle mouse button to drag it to the Pluto_Orbit node so that it has a black horizontal line above and below it to show a connection, as in Figure 2.26.

You have just grouped pluto_moon_orbit under Pluto_Orbit, a practice known as parenting. Now you need to parent pluto_moon under pluto_moon_orbit as well. Use the middle mouse button to drag pluto_moon onto pluto_moon_orbit. When you play back the animation, you will see that the moon is rotating around the planet, while at the same time Pluto and the moon are orbiting the Sun. Now that you've corrected Pluto's layout in the Outliner, it is similar to the layouts for the other properly working planets.

The file Planets_v3.mb in the Scenes folder of the Solar_System project on the CD will give you an idea of how this project should look. The first five planet systems are grouped and animated as reference, leaving the final four for you to finish.

Note

You can add objects to a group by MMB+dragging their listing onto the desired parent node in the Outliner. You can also remove objects from a group by MMB+dragging them out of the parent node to a different place in the Outliner.

GROUPING TERMINOLOGY

Grouping terminology can be confusing. Grouping Node A under Node B makes Node A a child of Node B. Node B is now the parent of Node A. Furthermore, any transformation, or movement, applied to the parent Node B will be inherited by the child Node A.

When you group Node A and Node B, both nodes become siblings under a newly created parent node, Node C. This new node is created just to be the parent of Nodes A and B and is otherwise known as a null node. To group objects, select them and choose Edit → Group. Parenting nodes together places the first selected node under the second selected node. For example, if you select Node A, Shift+select Node B, and then choose Edit → Parent, Node A will group under Node B and become its child. This is the same procedure as MMB+dragging Node B to Node A in the Outliner as you did with Pluto's moon and Pluto itself.

A playblast, as it's called in Maya, simply outputs the view panel's view into an image sequence or AVI movie. You can also save the image sequence or AVI to disk if you like. Playblasting is done mainly to test the look and animation of a scene, especially when its playback is slow within Maya itself.

Once you have your Solar System animated, you should output a playblast by following these steps:

Figure 2.27. Select the Option box for Playblast.

Figure 2.29. Creating a Playblast movie file is easy.