Looking to convert all single valence node crossings into roundabouts

01-30-2018 10:21 AM
New Contributor

I'm not sure what the best way to go about this would be. I'm thinking it should be a simple conditional rule that converts the shape's type to roundabout if its corresponding node has a valence of one, but I just started getting into CityEngine a few days ago and am still grappling with CGA. Is there a way to control shapes based on their underlying graph properties?

Thank you for any help in advance!

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Esri Regular Contributor

Hi Nate,

Thank you for this question.

The CGA street rules work on CityEngine dynamic shapes and their attributes.

By changing the underlying graph properties, the shapes are automatically regenerated.

Here is a Python script to accomplish this task:

Created on Apr 23, 2018

@author: ESRI R&D Center Zurich 
from scripting import *

# get a CityEngine instance
ce = CE()

def findDeadEnds(nodes):
    deadEnds = []
    for node in nodes:
        if ce.getAttribute(node,'valency') == 1.0:
    return deadEnds      

if __name__ == '__main__':
    # get selected nodes
    nodes = ce.getObjectsFrom(ce.selection(), ce.isGraphNode)

    # get all dead end nodes
    deadEnds = findDeadEnds(nodes)
    # set all dead ends to 'Roundabout'
    ce.setAttribute(deadEnds, '/ce/crossing/type', 'Roundabout')
    ce.setAttributeSource(deadEnds, '/ce/crossing/type', 'USER')
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