Default Start Rules
Street and intersection shapes generated within the CityEngine consist of different shape types. Each shape type is defined by its start rule.
Standard start rules are: Street, Sidewalk, Crossing, Junction, Freeway, FreewayEntry, Roundabout, RoundaboutIsland, and Joint.
The shape types are illustrated in the following figure.
|Color||Shape start rule||Created by|
|Sidewalk||Street, and all intersection types|
|Joint||Intersections with only 2 adjacent streets|
|Crossing||Crossing or Smart intersections|
|Junction||Junction or Smart intersections|
|Freeway||Freeway or Smart intersections|
|FreewayEntry||Freeway or Smart intersections|
|Roundabout||Roundabout or Smart intersections|
|RoundaboutIsland||Roundabout or Smart intersections|
Note: Shapes have by default no rule file assigned. Therefore, if you like to work with these default start rules you have to define the CGA rules "Street", "Sidewalk", "Crossing", "Junction", "Freeway", "FreewayEntry", "Roundabout", "RoundaboutIsland", and "Joint". These rules will be the starting point for geometry generation.
Street Shape UV Values
For details of the UV coordiantes, see Street and Intersection Shape UVs.
Reset Shape Attributes
Since start rules can be overridden, users may want to use the Reset Shape Attributes tool to revert the start rules to the default values. To execute the tool, select a set of shapes and then choosefrom the main menu.
Because the internal shape creation algorithm computes the intersection shapes for each node individually, conflicts can occur. Usually, conflicts occur when the distance between two nodes is very small. In this case, at least one node is located inside the shape of a neighbor node.
Conflicting segments are marked with a red dashed line. The error color can be changed in the Viewport Preferences.
To resolve conflicts, different actions can help:
Cleanup the graph, see Graph Cleanup Tool
Edit the graph network, see Editing Street Networks Manually
Use the Street Tool to edit curves, change street widths or move nodes.
Which action to choose depends on the required level of control. It's a tradeoff between automation and quality of the result.
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