The essence of animation is change over time. In Maya, almost anything you create can be changed over time or animated. The most common method of animating is called keyframe animation. Keyframing refers to a 2D animation technique in which the most important poses (keys) are drawn first. The frames between the key poses (in-betweens) must then be drawn. The process is similar in 3D digital animation with one definite advantage: you can indicate which frames are the keyframes, and the computer will automatically calculate the in-between frames.

When you set a keyframe (or key) in Maya, you record a value for an object attribute at a specific time. When you set several keys at different times with different values, Maya generates the attribute values between those times as the scene plays. The result is the illusion of movement or change over time.

Setting keys

There are several ways to set keyframes in Maya. First, you must select the objects that have the attributes you want to key. You then set a key by selecting Animate > Set Key. The attributes set by this menu item depend on the Set Key option settings.

You can also set a key with the following hotkeys:

S Sets a key the same as Animate > Set Key
Shift-W Sets keys for translation
Shift-E Sets keys for rotation
Shift-R Sets keys for scale

The Channel Box and the Attribute Editor display attributes you can edit and animate. To set keys, right-click an attribute box or name and select Set Key from the pop-up menu. This menu is not available for attributes you cannot key.

Auto Key automatically sets keys on attributes when you change the current time and attribute value. A key must already exist for an attribute before you use Auto Key.

Using Animation Controls

With Maya's animation controls, you choose how to key and play an animation. These controls include the Time Slider, Range Slider, and Playback Controls. You can also quickly access and edit animation preferences from the animation controls area. Between the Range Slider and the Animation Preferences button are the current character control features and the automatic keyframing (Auto Key) button.

The Time Slider

The Time Slider displays the playback range and keys you've set for a selected object. Keys are displayed as red lines. The box at the right of the Time Slider lets you set the current frame (time) of the animation. The current frame is displayed as a gray block on the Time Slider.

To change the current time, you can click with your left mouse button anywhere on the Time Slider. The scene jumps to that time in the animation. If you drag the mouse in the Time Slider or hold down your keyboard's k key as you drag horizontally in any view, the scene updates with your mouse action. This is called scrubbing.

Click the Time Slider with the middle mouse button or hold down the k key and middle-mouse drag horizontally in any view, and the scene does not update, but the Current Time Indicator moves to show your new current time. This is useful, for example, if you want to key an object at some frame based on a prior position of other objects.

By default, dragging in the Time Slider updates only the active view. All views can be set to update by changing Playback settings to Update View All in the animation Preferences window. The k key operations work the same in all Maya windows that display a timeline, for instance, the Graph Editor.

To move or scale a range of animation in the Time Slider, shift-drag along the Time Slider to select a range of time. The selected time range is red, with start and end frames shown in white numbers at the ends of the selection block.

Drag the black arrows at either end of the selected range to scale the keys in that range along the Time Slider. Drag the black double arrows at the center of the selection to move the keys in that range along the Time Slider. To select the entire range of the Time Slider, double-click the Time Slider.

The Range Slider

The Range Slider controls the range of frames that play when you click the play button. The Start Time and the End Time fields set the start and end times of the animation. The Playback Start Time field shows the current start time for the playback range. If you enter a value in this field that is greater than the Playback End Time, the Playback End Time is adjusted to one time unit greater than the Playback Start Time. The Playback End Time field shows the current end time for the playback range. If you enter a value in this field that is less than the Playback Start Time's value, the Playback Start Time is shifted to one time unit less than the Playback End Time. You can enter a positive or negative value in any of these fields.

The Range Slider bar lets you control the playback range of your animation up to the limits of the Animation Start/End settings. Drag the Range Slider bar to change the playback range. Drag the boxes at the ends of the Range Slider to scale the playback range. Double-click the Range Slider bar. The playback range is set to the range values in the Animation Start/End fields of the Preferences window. To return to the prior playback range, double-click the Range Slider bar again.

The Playback Controls

The Playback Controls control animation playback. You'll undoubtedly recognize the conventional buttons for play and rewind (return to the start time). The stop button appears only when the animation is playing. To find out which operation a button represents, hold the mouse pointer over it.

The Animation Preferences button displays a window for setting animation preference settings such as the playback speed. We will look at these settings in detail as we do the first assignment.