Setting the Start Rule

In addition to the rule file, a shape requires are valid start rule to trigger the model generation. If no valid start rule is found while a rule file is being assigned, the Start Rule Selector pops up.

Start Rule

A Start Rule is required for rule file model generation. The Start Rule can be set manually, or set from the Start Rule Dialog. The Start Rule Dialog is shown

Start Rule Dialog

The Start Rule Dialog displays all rules that can be applied as start rules.

Rules that are marked as start rules (see CGA annotations) are displayed in bold.

The Start Rule Dialog

Depending on the selected shapes and their start rules, the Start Rule Dialog shows the options to

Choose Skip or Cancel if you don't want any Start Rules to be modified.


CityEngine tries to automatically detect and suggest start rules from a rule file. Use the annotation @StartRule to explicitly mark a rule as a start rule. More on CGA annotations.

Setting the Start Rule manually

The start rule can be set on shapes via the Inspector. Select a set of shapes, locate the Start Rule field in the Shape tab of the Inspector, and type in the desired Start Rule. Note that no model will be generated if an invalid start rule is set.

Assigning Rule Files

Default Start Rules

Copyright ©2008-2018 Esri R&D Center Zurich. All rights reserved.