Assigning a Path Controller

The Path controller tells an object to follow the spline path that you, pick for it. It is commonly used for animating cameras—for architectural fly-throughs, “first person” sequences, or typical camera-dolly techniques used in movies—but can be used for any object. The up-side of the Path controller is that you can draw out the desired trajectory with an ordinary line and edit it at any time. The down-side is that when you edit the path, all your keys telling the object where it is along the path at what time are altered.

1.  Reset MAX.

2.  Using Create tab Ø Shapes Ø Line, create a wandering line around the top viewport.

	TIP You can also use a NURBS curve as a path, for its particular smoothness.

3.  Create a target camera in the top viewport, dragging the target wherever you like.

4.  Select the camera and choose Track View Selected from the shortcut menu.

	WARNING Be sure the camera body, not the target, is selected.

5.  In the Motion tab, highlight the Position track and assign a Path controller. If you now try to move the camera, you will not be able to do it.

	NOTE When an object doesn’t have a position track, or it has a position controller that determines position very precisely (like the path or expression controllers), you will not be able to move its position in the viewport.

6.  Under Path Parameters in the Motion tab, click Pick Path and then select the line you made. The camera moves to the first point of the line.

7.  Play the animation. The camera animates from the beginning to the end of the path over the active time segment.

You will probably notice that the target does not move. That is because it is an independent object and is not affected by the camera body’s movements. You can animate this manually, apply another path to it, or link it to another object.

Nesting the Path Controller under a List Controller

The List controller allows you to combine several controllers together, nested under the list. When you change a track to a list controller, it keeps the original controller and adds a new track available for another controller to refine the effect of the first one. Each time you assign the Available track, a new one is created.

If we assign a noise controller to the position track to add noise, we will replace the controller we just assigned. To nest the noise with the forward motion, we need to use a list controller.

1.  Highlight the position track and this time assign a Position List controller. A plus sign appears in front of the position track.

2.  Open the position track to reveal two subtracks: the Path controller we assigned before, and an Available track. This is the one we will add the jitter to.

Nesting a Noise Controller with the Path Controller

The Noise controller randomizes the value of the track, with settings for the overall strength and frequency of the noise, as well as a separate animatable Noise Strength track.

Let’s add noise to our path by adding the noise controller to our available position list track.

1.  Select the available track and assign a noise controller.

2.  Play the animation. The camera is now moving along the path, but jittering as it goes along. The noise is a bit strong, though, so we should turn it down.

3.  Open the Track View Selected for the camera and then open the camera tracks to reveal Noise Position track.

4.  Highlight the noise position track and click the Properties button. In this dialog, you can set the X, Y, and Z components of the jitter separately.

5.  Turn the noise strengths way down. Notice that there is also a Noise Strength track, because noise strength is also animatable. If you like, you can nest an XYZ controller under this and animate each strength separately.

6.  You can also reduce the Frequency value (also in the Properties dialog box) to make the jitter less frenetic.

7.  Save this file as cam_path.max for use in the next chapter.

Using Other Controllers

The possible uses of different controllers is nearly limitless. Table 6.7 describes other controllers available in MAX and examples of how they might be used.

© 2000, Frol (selection, edition, publication)