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146 Chapter 4: Obj ect Properties
selected parameter. To access the link, click the
Go button.
Go—If the URL text box contains a valid URL,
clicking Go opens the URL in a separ ate browser
window.
Notes—Containsany comments on the parameters.
This field is strictly for informational purposes.
Expression Techniques
In 3ds Max, you can use mathematical expressions
(rather than constant numbers) to express
parametervalues.Forexample,youcouldusethe
expression 24*6 to represent the number 144.
You can use mathematical expressions to control
the following object proper ties:
• Object p arameters, such as length, width, and
height
• Transform and modifier va lues, such as an
object’s position coordinates
Parameter wiring (page 2–411),theexpression
controller (page 2–320),andthenumerical
expression evaluator (page 1–13) all use
expressions, which are described in this topic.
An expression is a mathematical function that
returns a value. You can use expressions to control
thefollowingsceneelements:
Scene element Calculatable property
Creation
parameters
Any numeric creation parameter
Transforms
Position [X, Y, Z]
XRotation
YRotation
ZRotation
Scale [X%, Y%, Z%]
Scene element Calculatable property
Modifiers Any numeric modifier parameter
(including creation parameters)
Materials Colors [R, G, B]
Any numeric material parameter
Note: Expressions only work with the individual
XYZ components of Euler rotation. You can’t
assign an expression to TCB rotation or other
kinds of rotation controllers.
The links below are to the sections tha t follow in
this topic.
Expression Return Types (page 1–146)
Operators (page 1–147)
Var iables (page 1–148)
Functions (page 1–148)
See also
Tr igonometric Functions (page 1–150)
Vectors (page 1–151)
Expression Controller Techniques (page 2–324)
Ex press ion R etur n Types
Thetypeofvaluereturnedbyanexpression
depends on the kind of controller:
• Float expressions return a floating-point
scalar value (For example, 5.617). Sca lars are
used in the animation controllers of numeric
parameters.
If the parameter has an integer va lue, the
expression rounds the float value to the nearest
integer.
• Position, Scale, and Point3 expressions return a
three-component vector. For example, [5, 18,
24]. The vector can represent an object’s X,Y,Z
location,percentscalinginX,Y,andZ,ora
color (RGB values) in a material.