Expression Reference

The tokens below can be inserted into expressions using the ExprStr parameter of the AddExpr or SetExpr commands. You can combine and nest these tokens to create complex expressions using brackets ( and ) as well as operators and numeric values you type.

These tokens are grouped as follows:

• Variables:

- Constant Variables which are available for building expression strings (TRUE, FALSE, PI, E, LinearInterp, SplineInterp).

- Time Variables which can be used to represent specific frames (current, first, last, etc.).

- Node Pointer Variables which can be used to represent the current object or model.

• Operators:

- Math Operators which can be used to perform mathematical operations (+, -. *, /).

- Condition Operators which can be used to perform logical operations (==, !==, <, <=, >, >=, &&, ||).

• Math functions:

- Trigonometry Functions (sin, cos, tan, etc.)

- Exponent Functions (log, exp, pow, sqrt)

- Value Functions (abs, min, max, av)

- Random Functions which allow you to generate noise or random values, optionally controlling the range or type.

• Functions to retrieve or link scene data:

- Distance Functions

- Link Parameter Functions

 

When you set an expression on a parameter, you can access the new Expression object from the Parameter.Source property. The Expression object contains four parameters which are available by calling the Parameters property on the Expression object:

• Active—true by default; setting this parameter to false mutes the link.

• Target—returns the name of the target parameter (that is, the parameter that owns the expression). Read only.

• Definition—this is the real meat of the expression: you can change this string definition if you need to change the link or even remove the link entirely.

• Comment—nothing specified by default.

In addition to these four parameters, another parameter or property becomes available from the Expression object if you use any of the Link Parameter Functions.

 


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