In this tutorial I'm showing how to create parametric windmill shape using arc as a base element.
[File Download]
https://github.com/jhorikawa/GrasshopperHowtos/tree/master/0121%20Arc%20Windmill
[Facebook Page]
https://www.facebook.com/Parametric.Design.with.Grasshopper/?fref=ts
[Book Page]
http://www.bnn.co.jp/books/8482/
[Buy on Amazon]
http://bit.ly/parametricdesignwithgrasshopper2
