[epsilon-devel] Re: draw regular poligons

[Luca Saiu]

  Hi Matteo.

Matteo Golfarini wrote:
> that is the code i implemented in the week end ... i don't know if is 
> the best way for implement it because i forgot my matematics books but i 
> think it's work  .......

  *REGULAR* polygons? I thought you were implementing *generic* 
polygons, whose vertices were represented as lists of points... However 
don't mind, also regular polygons can be useful; and probably they are 
more difficult to implement than non-filled generic polygons.

  However you forgot the attachment :-).

  About non-filled generic polygons, here are some little hints:
* you can see a segment as the pair of its extreme points (P1, P2). 
Order does matter, i.e. (P1, P2) is different from (P2, P1).
* A polygon is a sequence of "linked" segments. "Linked" means that if 
the i-th segment is (P1, P2) then the (i-1)-th has P2 as its second 
extreme point, and the (i+1)-th segment has P2 as its first extreme point.
* You can see the list of points as a circular list: the point "before" 
the first one is the last one.
* Draw each segment in order with show_line. The last one, which closes 
the polygon, requires a very little trick.

> now i must go to study a little of spanish, today i've my spanish exam and 
> (for now) i don't speek ...... :)
  Ok. Best wishes, and see you soon.

--
Luca Saiu, maintainer of GNU epsilon
http://www.gnu.org/software/epsilon