[Ipe-discuss] CGAL points generator ipelets in Ipe 7
Sebastien Loriot (GeometryFactory)
sloriot.ml at gmail.com
Tue Mar 16 08:08:55 CET 2010
[cristo] wrote:
> Hello all,
>
> I'm writing an Ipelet in Lua that uses a set of points (markers) as
> input. I sort the points using their x coordinate, which I obtain using
> the getPosition() function of each marker object.
>
> My script works fine when I use a set of points created either manually
> (i.e. placing the points on the page with the mouse) or by using one of
> the CGAL ipelets in ipelets -> Generators -> Points *, but I'm having
> problems when I use a set of points with some points created manually
> and some ones created by the generators.
>
> Doing some debug I found that the coordinates of the two sets of points
> (manually placed and generated) doesn't seem to be referenced to the
> same coordinate system, as all the manually placed points have always
> positive values and the generated ones have sometimes negative values,
> and the ranges of them are different.
>
> ¿Does anybody have any idea of why this happens?, ¿Are not all the
> objects on a page referenced to the same coordinate system?
>
Just an hint: a CGAL ipelet generator creates points in a square or
circle centered at (0,0). A transformation is then applied to translate
all the points at the center of the page. You probably should have a
look at the matrix() function of ipe::Object.
hth
S.
> Thanks in advance.
>
>
>
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