When you add keys to an object to control its animation using modifiers, the modifiers remain with the object and can be revisited and altered as needed. However, if you have multiple objects that follow the same set of keys, such as for a crowd scene, then including a set of modifiers for each object can increase the overhead many times over. A simple solution is to bake all the keys into the object, allowing all the keys to be pulled from an external file. This frees the resources required to animate multiple objects and makes the animated keys portable. The Point Cache modifier makes this possible.
NEW FEATURE | The Point Cache 2 modifier is new to 3ds Max 9. |
You also can use the Point Cache modifier when playback in the viewport is too slow because Max needs to compute the vertex positions of a huge number of vertices. Reading their position from a separate file increases the playback speed. You also can use the file on a cloned object to control its motion at a different speed.
The Point Cache modifier records the movement of every vertex of an object to a file. Point Cache files have the .pc2 extension. To create a Point Cache file, click the New button and name a new file on the hard drive. Then set the range of the animation to capture and click the Record button. Once recorded, the total number of points along with the sample rate and range are displayed for the active cache.
Caution | Point Cache files can be loaded and used only on objects with the same number of vertices as the original used to record the file. |
If you select the Disable Modifiers Below option, then all modifiers below the Point Cache in the Modifier Stack are disabled. You can enable the Relative Offset option and set the Strength value to cause the cached animation to be exaggerated or even reversed. In the Playback Type section, you can control the range of the animation.
As an example of using the Point Cache modifier, we'll use a tree that is bending under violent forces such as a hurricane and duplicate it many times.
To create a forest of trees in a hurricane, follow these steps:
Open the Bending tree.max file from the Chap 29 directory on the DVD.
This file includes an animated tree swaying back and forth using the Bend modifier.
Select the tree and choose the Modifiers Cache Tools Point Cache menu to apply the Point Cache modifier to the tree.
In the Parameters rollout, click the New button and create a file named "Bending tree.pct". Then click the Record button to save all the animation data to the file.
Select the tree and delete its Bend modifier. Then use the Tools Array dialog box to create several rows of trees. Be sure to create the trees as copies and not instances.
Select several random trees and change the Playback Type to Custom Start and change the Start Frame to cause some random motion.
Press the Play Animation button to see the results.
Figure 29.18 shows several of the trees being moved about by the storm.
Figure 29.18: Using the Point Cache modifier, you can animate a whole forest of trees.