kicad-developers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>]

On Tue, May 13, 2014 at 02:52:05PM -0400, Kelton Stefan wrote:
> Lorenzo, I'm not exactly sure what the 'butterfly' is that you mention I
> should produce a summary test with. Can you explain?

This is a quad:

3        2
 --------
|        |
|        |
|        |
|        |
 --------
4        1

swap the node 1 and 4, twisting the polygon, and you have the butterfly:

3        2
 --------
 \     /  
   \ /    
   / \    
 /     \  
 --------
4        1

AFAIK that's the simplest self intersecting polygon you can have. Also
the bane of all the polygon algorithms (it would be convex, too, anyway!)

-- 
Lorenzo Marcantonio
Logos Srl