Apple MA434Z/A User Manual - Page 78

Using Expressions in Parameters An expression is any non-numeric entry, such as a variable or a mathematical calculation. Any parameter can use an expression. Some expressions, such as time, are extremely simple. When you type the expression variable "time" into a value field, Shake returns the numeric value of the current playhead position. For example, if the playhead (in the Time Bar) is parked at frame 1, typing "time" into a value field returns a value of 1 in that field. Entering an expression consisting of any letter (whether valid or not) activates a plus sign (+) to the left of the parameter name. To edit a parameter's expression, click the plus sign to open an expression field underneath. If the parameter has an expression and you make an adjustment to that parameter's slider, the expression is removed in favor of your numerical change. If the parameter is animated, however, these special expressions are recognized by Shake and are not removed when the slider is adjusted. For more information on animating parameters, see Chapter 10, "Parameter Animation and the Curve Editor," on page 291. Note: You can also remove an expression by right-clicking the field and selecting Clear Expression from the shortcut menu. You can modify expressions in various ways: • To load or save an expression, use the right-click menu. • To create extra sliders to build complex expressions (and still allow interactive input), right-click the field and select Create Local Variable. To remove a local variable, rightclick and select Delete Local Variable. For a lesson on using local variables and expressions, see Tutorial 4, "Working With Expressions," in the Shake 4 Tutorials. For a list of mathematical expressions and variables, see Chapter 30, "Installing and Creating Macros," on page 905. 78 Chapter 1 An Overview of the Shake User Interface