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.
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
- When the
Start Rule button is clicked in the Inspector
- when a rule file is assigned to shapes with an empty or invalid start rule (invalid means no rule is found in the rule file that matches the start rule)
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.
Depending on the selected shapes and their start rules, the Start Rule Dialog shows the options to
- Overwrite invalid start rules: Set selected start rule to all shapes with invalid or empty start rule
- Overwrite all start rules: Set selected start rule to all shapes
Chooseor 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.
Default Start Rules
- Shapes generated inside CityEngine from a street network (by block subdivision or street shape creation) have their start rule set to a default value during creation (Lot, LotInner, Street, Sidewalk, ...). These start rules can be reset to their initial value with
- Shapes created manually with the Create Shape Tool have their start rule set to Init by default
- Shapes which are imported from a .obj file (arbitrary geometries) have their start rule set to the obj group name by default.
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