topic Re: How to size a shape based on world location? in ArcGIS CityEngine Questions

How to size a shape based on world location?

RobertYu — Fri, 17 Mar 2017 05:04:32 GMT

I am creating a number of shapes that represent buildings. (See attached.)

I want to have the buildings facing south to be shorter, and progressively taller as you go north.

How would I capture that using shape grammar? Suggestions appreciated!

-Robert

Re: How to size a shape based on world location?

LR — Fri, 10 Dec 2021 22:23:50 GMT

Maybe you could use the split.index, like so:

@StartRule
Lot --> 
    alignScopeToAxes(y)
    split (x){10: Spli}*

Spli -->
    extrude(split.index)‍‍‍‍‍‍‍

Re: How to size a shape based on world location?

RobertYu — Mon, 20 Mar 2017 22:49:21 GMT

That is brilliant. Thank you!

Re: How to size a shape based on world location?

CherylLau — Tue, 21 Mar 2017 15:25:10 GMT

If you need to know the positions of the buildings relative to the world, you could also convert scope coordinates to world coordinates using convert() (but using split.index is easier).

convert Function

Re: How to size a shape based on world location?

RobertYu — Tue, 21 Mar 2017 16:25:59 GMT

The next step is for the height of the buildings to respond to the sun location. For example,

I want the buildings along the southern edge of the lot to be low, and the neighboring ones

progressively taller. I haven't figured out how to get the heights of neighboring buildings, so I am

using the python export to get building locations and calculating the height using python.

Unfortunately, with Jython, I cannot import modules like "numpy" so it's becoming a bit

of kluge, doing a system call to a python script from within Cityengine's jython.

I feel I am approaching this problem the wrong way. Suggestions?

Re: How to size a shape based on world location?

CherylLau — Tue, 21 Mar 2017 16:36:18 GMT

Knowledge about neighboring shapes in CityEngine is really difficult and limited. It's currently limited to the occlusion queries in CGA. If you figure out a way to do it with Python, it's probably the only way to do it.

Re: How to size a shape based on world location?

RobertYu — Tue, 21 Mar 2017 17:00:49 GMT

Thanks for the information. Perhaps I can import the JTS geometry library into CityEngine to extend the jython functionality.

Update: Getting JTS into cityengine worked, using this article pyright: jython + the JTS geometry library. Note I had to be

careful with the coordinate system: CityEngine -z is JTS y.