# City growth example

**URL:** <https://discourse.processing.org/t/city-growth-example/38562>\
**Category:** Project Guidance\
**Created:** [August 30, 2022, 11:29pm UTC](https://discourse.processing.org/t/city-growth-example/38562 "2022-08-30T23:29:06Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![TimoL](https://avatars.discourse-cdn.com/v4/letter/t/9fc29f/32.png) [@TimoL](https://discourse.processing.org/u/TimoL)\
**Post date:** [August 30, 2022, 11:29pm UTC](https://discourse.processing.org/t/city-growth-example/38562/1 "2022-08-30T23:29:06Z")

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> please format code with \</\> button \* [homework policy](https://discourse.processing.org/faq/#homework) \* [asking questions](https://discourse.processing.org/t/2147)

Im trying to find a processing example I remember seeing years ago. It was a a bunch of random points that start moving in random directions creating a line behind them.

Points would also randomly spawn along each line and grow perpendicularly forming a new line.

In the end it would resemble a city road map.

Does anyone know what Im talking about? It had very earth colours to it.

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**Author:** ![Chrisir](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/chrisir/32/45_2.png) [@Chrisir](https://discourse.processing.org/u/Chrisir)\
**Post date:** [August 31, 2022, 9:52pm UTC](https://discourse.processing.org/t/city-growth-example/38562/2 "2022-08-31T21:52:45Z")

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don’t know

see [Converting coding challenge 'Self-avoiding walk backtracing' from p5.js to Processing (Java) - #20 by GoToLoop](https://discourse.processing.org/t/converting-coding-challenge-self-avoiding-walk-backtracing-from-p5-js-to-processing-java/35047/20)

keywords: Fractals and L-Systems, Brownian, Walkers

see [Examples / Processing.org](https://processing.org/examples)

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**Author:** ![solub](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/solub/32/333_2.png) [@solub](https://discourse.processing.org/u/solub)\
**Post date:** [September 1, 2022, 8:25am UTC](https://discourse.processing.org/t/city-growth-example/38562/3 "2022-09-01T08:25:32Z")

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Hi @TimoL,

Could it be that you are looking for Jared Tarbell’s “[Substrate](http://www.complexification.net/gallery/machines/substrate/)” algorithm ?

If so, there’s a dedicated thread with example code you can find here, on this forum:

> [@Trying to understand the "Substrate" algorithm](https://discourse.processing.org/t/trying-to-understand-the-substrate-algorithm/3031):
>
> Dear all, I would really appreciate if someone could help me decipher some parts of Jared Tarbell’s “[substrate](http://www.complexification.net/gallery/machines/substrate/)” algorithm. For those who are not familiar with this famous sketch, here is a recap in Tarbell’s own words: A single line (known internally as a “crack”) begins drawing itself from some random point in some random direction. The line continues to draw itself until it either (a) hits the edge of the screen or (b) hits another line, at which point it stops and two more lines begin. Th…

For procedural city generation, there’s also [this approach](https://www.tmwhere.com/city_generation.html) from Sean Barrett which is a simplification of Parish and Müller’s [Procedural Modeling of Cities (2001)](https://graphics.ethz.ch/Downloads/Publications/Papers/2001/p_Par01.pdf) as explained [here](http://nothings.org/gamedev/l_systems.html).

 ![__](https://canada1.discourse-cdn.com/flex036/uploads/processingfoundation1/original/3X/7/5/75d099cb286673cd6949526aa6616792997ad1c5.png)

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**Author:** ![TimoL](https://avatars.discourse-cdn.com/v4/letter/t/9fc29f/32.png) [@TimoL](https://discourse.processing.org/u/TimoL)\
**Post date:** [September 2, 2022, 12:25am UTC](https://discourse.processing.org/t/city-growth-example/38562/4 "2022-09-02T00:25:21Z")

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Amazing!  
thanks @solub thats exactly what I was searching for 🙂