Autodesk 62205-051408-9001 User Guide - Page 327

Adding Expressions ❚❘❘ The following table lists the most common punctuation that you use in Combustion expressions. Use () "" "..." ; // /*and*/ For Parentheses around arguments. Quotations around paths. Quotations around paths and three periods for relative paths. Semicolon at the end of a statement. Writing hidden comments. Everything between these symbols, even on multiple lines, is not seen by expression. Please keep in mind the following basic rules when writing expressions: • Expressions must be consistently returning the same values from one replay to another. • Never use Math.random since it does not consistently return the same values from one replay to another. • Case matters! While and while are not the same thing. • Spaces and line breaks between tokens (i.e. a variable, name, number, function name, or other entity) don't matter. • A space or line break within a token translates into two tokens and generates a syntax error. For example, 123 / 12 3 (The latter is two tokens and generates a syntax error.) Adding Expressions You can create channel animations by adding expressions to channels of a layer or an operator via the Timeline or the Expression Browser. To add an expression using the Expression Browser, see Using the Expression Browser. To add an expression using the Multi-line Editor, see Adding an Expression to a Channel. For example, if you have a Lens Flare in your composite, you can add an expression to the Lens Flare Strength, to the X and Y Flare Center, to the X and Y Axis, to the Red, Green, and Blue Color, and to the Rotation channel. As with keyframing, to add an expression, you need to display the layer and operator channel categories. To access the channel categories: 1. In the Timeline, click the Menu button. 2. Choose to display Operator Objects and Properties. The layer and operator channel properties are displayed in the Timeline. To choose which channels to display, do any of the following: • Click the Timeline Menu button and choose Show Only Animated Channels. Only animated channels are accessible in the Timeline. However, to display the animated channels, you need to expand the channel categories in the Timeline. Note: If you want to add an expression to a channel that is not animated, make sure Show Only Animated Channels is not selected. • CTRL-click the triangle next to a branch in the Timeline to display the channels of all the operators and layers of the branch. • CTRL-click the triangle next to a layer in the Timeline to display all the channels of the layer. 311