CGAL users discussion list

[Martin Baroš <>]

Yes! That's exactly what I need and I then I guess I will be abto to use prepared PainterOstream, that is  ready to draw some of cgal data structures.

Thank you all for your answers.

Best
Martin

On Sat, Aug 29, 2009 at 12:06 PM, <> wrote:

Quoting "Martin Baroš" <>:

I'm just not sure how could I draw it in correct way.

In case, that I would have in arrangement just line segments it would be
easy, but if I have curved lines I can get source and target of the curve
easily, but how to draw curved line between start and end points
correctly?
I still can't find any suitable Qt object for this drawing.

If you cannot draw the curve as is, then you need to approximate it with a
polyline and draw the linear segments that comprise the polyline. Some of
the traits classes in the arrangement package contain an operation that does
the approximation.

That is interesting idea, thank you for this hint!
I just wonder if this approximation is needed also in case, when I put in
arrangement circle. As I know circle is in arrangement divided in two
X_monotone_curve objects. Then when I want to fetch it from arrangement and
draw it - isn't there any more straightforward solution than approximation?

Perhaps you can use arrangement-with-history. This data structure retains the original curves inserted into the arrangement, and associates each x-monotone curve with its original curve.

Best regards and thx a lot for answer
Martin

On Fri, Aug 28, 2009 at 11:28 AM, <> wrote:

Quoting "Martin Baroš" <>:

I think so. As far as I know, there is not graphics view item for
arrangement.
You'll need to draw each curve of the arrangement one by one.

 I'm just not sure how could I draw it in correct way.

In case, that I would have in arrangement just line segments it would be
easy, but if I have curved lines I can get source and target of the curve
easily, but how to draw curved line between start and end points
correctly?
I still can't find any suitable Qt object for this drawing.

If you cannot draw the curve as is, then you need to approximate it with a
polyline and draw the linear segments that comprise the polyline. Some of
the traits classes in the arrangement package contain an operation that does
the approximation.

Thank you for your answers, I really appreciate that.

Martin


On Thu, Aug 27, 2009 at 10:26 AM, Laurent Rineau (GeometryFactory) <
> wrote:

 On Wednesday 26 August 2009 16:10:54 Martin Baroš wrote:

> Hi,
> thank you for your answer.
> I'm using Qt Graphics View framework and I can draw geometric objects
> without problems.
> But I'm still not sure how to draw content of arrangement - should it
be
> done by fetching X_monotone_curve one by one from arrangement and then
> drawing in Qt scene?

I think so. As far as I know, there is not graphics view item for
arrangement.
You'll need to draw each curve of the arrangement one by one.

--
Laurent Rineau, PhD
Release Manager of the CGAL Project
http://www.cgal.org/
R&D <http://www.cgal.org/%0AR&D> Engineer at GeometryFactory
http://www.geometryfactory.com/
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