2009

The value of the controller script must be a matrix3 value. A matrix3 value is
a 4x3 3D transformation matrix. For more information, see the Matrix3 Values
topic in the MAXScript reference.
Writing Controller Scripts
The software interprets the text you type into the Script text box as the body
of a MAXScript block expression. You can type as many expressions as you
want on as many lines as you want, and they are evaluated in turn. The value
of the last expression is taken as the controller value. This must yield a matrix3
value.
Since the text is inside a block expression, you can declare local variables that
are visible only within the script and are temporary for one evaluation. You
can also declare or access global variables that are shared with all other scripts
in MAXScript and hold their values from one evaluation to the next.
A controller is always evaluated with respect to a specific animation time by
the software. This might be the current time slider or incrementing frame
time if an animation is playing, or a rendering is under way. In the case of
Script controllers, the time being evaluated is used to establish an automatic
"at time" context around the controller script, so any properties you access
(outside of other explicit “at time” expressions) yield the correct values for
the current controller evaluation time. This means you don't have to do
anything special in your scripts to work at the correct time. You can access
the evaluation time with the standard MAXScript variable, current Time. You
can also reference scene property values at other times by using "at time"
expressions in your scripts, as in regular MAXScript programming.
Assign Nodes and Tracks to Variables
When you need to refer to nodes in your scene or to animation tracks, it is
recommended that you use the Script controller variable toolset to create
variables to assign to any particular node or controller track. This way, if you
decide to later on rename your scene objects, the script controllers using these
objects are preserved because the variables maintain the link to the nodes.
Otherwise, if you assign, for example, a node to a variable manually in the
dialog's Expression window, that link becomes broken as soon as you rename
that particular node.
NOTE It is especially important to assign nodes and tracks to variables with the
corresponding buttons when using XRef scenes and objects.
3262 | Chapter 15 Animation