XPresso (R8's node-based expression editor) can be a bit daunting at first glance. Bjorn, of MAXON Germany, has assembled a series of examples of common animation tasks that should help to ease the pain of understanding and utilizing this powerful feature.
XPresso's well worth putting the time and energy into learning...now, have at her!
'Trailing' is achieved by transfering the lead object's previous positional and rotational values to the objects 'following.'
Click to play Quicktime movie
These values can be obtained from the Object node. It allows you to set the number of previous values that should be stored (History Depth), as well as addressing which of those values should be used (History Level).
In the example, the History Level is provided as a property of the Xpresso tag.
You can use this setup to create a vector motion blur like effect (motion trails). The effect is pulled off by having partly transparent objects tightly follow the leader.
For further explanation, you will find detailed remarks on how the expression works in the Xpresso editor in the project file above.
