Chamfer Lot Corners

Question

Good morning,

For many of our Chinese projects, we are faced with the problem of creating parcel boundaries that have chamfered corners. This can be a laborious task in CAD, particularly if you have hundreds of blocks.

[ATTACH=CONFIG]13732[/ATTACH]

It seems like CityEngine could be used to automatically generate these parcel lines (in addition to curb lines, etc), but I can't come up with a way to actually do it.

What we would be interested in is just a simple chamfer on each of the lot's corners, before additional rules are applied. In our case, we are NOT using built-in lot subdivisions, so just assume it's the entire block that needs to be setback somehow. In the simplest case, the chamfer distance is the same in all directions, but that value should be user adjustable.

Any thoughts on how to approach this problem?

chamfered block.jpg

VHolubec_20-1744114950100.png

MatthiasBuehler1 · Answer

hey Daniel !

instead of the setback() operation, just use the shapeO() operation.

let's assume your Block's cornerWidth is 10 meters.
have a precise look at this code for the 'Lot' Start Rule and play with it's 4 attributes. you'll notice that as long as the setback distances are big enough, the previously chamfered corners will disappear. ( utilizing a geometric dependency in code )
attr Front_Setback = 15
attr Right_Setback = 15
attr Back_Setback = 15
attr Left_Setback = 15

Lot -->
 shapeO(Front_Setback,Right_Setback,Back_Setback,Left_Setback) { shape : color(.9,.7,.7) SetbackZone. | remainder : color(.2,.7,.7) DevelopmentZone.}

to find the Block Subdivision Settings :
Help > Manual > Shapes > Block Parameters

you could also search for 'Block Subdivision' in the top left search field in the manual, then second entry 'Block Parameters'

the docs on the shapeO() operation can be found :
Help > CGA Rule Reference > shapeO()

I hope this helps you find things a little quicker. We know the docs still have 'potential of improvement', but this is currently being organized.

Let me know if this worked !

Cheers !

DanielO_Shaughnessy · Answer

hi Daniel,

that's easily possible : Just select your Block, then set the cornerWidth parameter to something larger than 0. (Just below the Block Subdivision Type parameter)

Let me know if it works !

Yes, this works quite well - thanks! Just a bit of feedback: it would be nice if information like this was searchable in the Help documentation.

So here is one further complication. In addition to creating the chamfered parcel boundaries, we also need to have the "development zone" within that parcel maintain a (near) rectangular shape, instead of the octagon that gets created using the cornerWidth parameter. Ie, buidings should stay aligned to the streets instead of aligning to the chamfered parcel boundary. To do that, I could see using the chamfer to define lot setbacks, but any use of the "setback" operation will produce funky shapes.

[ATTACH=CONFIG]13739[/ATTACH]

Any ideas?

chamfered block2.jpg

MatthiasBuehler1 · Answer

hi Daniel,

that's easily possible : Just select your Block, then set the cornerWidth parameter to something larger than 0. (Just below the Block Subdivision Type parameter)

Let me know if it works !