3ds Max 2012 Bible - Kelly L. Murdock [378]
Some motions, such as drawing with a pencil, are natural motions for our hands, but they become very difficult when you're trying to animate using keyframes. This tutorial uses the Motion Capture controller and utility to animate the natural motion of drawing with a pencil.
To animate a pencil drawing on paper, follow these steps:
1. Open the Drawing with a pencil.max file from the Chap 35 directory on the CD.
This file has a pencil object positioned on a piece of paper.
2. Select the pencil object, open the Motion panel, and select the Position track for the pencil object. Then click the Assign Controller button, and double-click the Position Motion Capture selection.
The Motion Capture dialog box opens.
3. Click the X Position button, and double-click the Mouse Input Device selection. Then click the Y Position button, and double-click the Mouse Input Device selection again. In the Mouse Input Device rollout, select the Vertical option. This sets the X Position to the Horizontal Mouse movement and the Y Position to the Vertical Mouse movement. Close the Motion Capture dialog box.
4. Open the Utilities panel, and click the Motion Capture button. In the Motion Capture rollout, select the Position track, and get the mouse ready to move. Then click the Start button in the Record Controls section, and move the mouse as if you were drawing with the mouse. The pencil object moves in the viewport along with your mouse movements.
The Motion Capture utility creates a key for each frame. It quits capturing the motion when it reaches frame 100.
5. Click the Play Animation button (or press the / key) to see the results.
Figure 35.21 shows the scene after the Motion Capture controller has computed all the frames.
Quaternion (TCB) controller
The Quaternion (TCB) controller produces curved animation paths similar to the Bézier controller, but it uses the values for Tension, Continuity, and Bias to define their curvature. The benefit of this controller is that it enables objects to be rotated without having the problem of Gimbal lock, which can happen when the Euler XYZ controller is used. Gimbal lock can occur when two of the rotation axes become aligned, causing the object to lose one of its degrees of freedom.
The parameters for this controller are displayed in a single Key Info rollout. Like the Bézier controller rollouts, the Quaternion (TCB) controller rollout includes arrows and Key, Time, and Value fields. It also includes a graph of the TCB values; the red plus sign represents the current key's position, while the rest of the graph shows the regular increments of time as black plus signs. Changing the Tension, Continuity, and Bias values in the fields below the graph changes its shape. Right-clicking the track and selecting Properties from the pop-up menu opens the TCB graph dialog box, shown in Figure 35.22.
FIGURE 35.21
The Motion Capture controller and utility let you animate with a mouse, keyboard, joystick, or MIDI device.
FIGURE 35.22
This dialog box shows, and lets you control, a curve defined by the Tension, Continuity, and Bias values.
The Tension value controls the amount of curvature: High Tension values produce a straight line leading into and away from the key, and low Tension values produce a round curve. The Continuity value controls how continuous, or smooth, the curve is around the key: The default value of 25 produces the smoothest curves, whereas high and low Continuity values produce sharp peaks from the top or bottom. The Bias value controls how the curve comes into and leaves the key point, with high Bias values causing a bump to the right of the key and low Bias values causing a bump to the left.
The Ease To and Ease From values control how quickly the key is approached or left.
Note
Enabling the trajectory path by clicking the Trajectory button in the Motion panel lets you see the changes to the path as they are made in the Key Info rollout. •
Figure 35.23 shows three TCB curves assigned to the Position track of an object.