[Qt-interest] Detecting intersections in a QPainterPath

[Atlant Schmidt]

Ben:

  To simplify things, are there any bounds we can place
  upon the "problem space"?

  For example, is there a maximum XY rect that will
  encompass all possible paths?

  Asking the question from the opposite direction,
  are the vertices of the paths points specified as
  integer [X,Y] pairs or are they arbitrarily fine-
  pitched floating point pairs?

  If both limits can be applied (so you have a
  bounded space of integer points), we might take
  a different approach than if the space can be either
  arbitrarily large or arbitrarily "fine-grained".

                      Atlant


-----Original Message-----
From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Ben Swerts
Sent: Monday, August 09, 2010 17:07 PM
To: qt-interest at trolltech.com
Subject: [Qt-interest] Detecting intersections in a QPainterPath

Hello all,

I have a QPainterPath created from a number of line and arc segments. This
path is allowed to be concave but it is not allowed to be self-intersecting.

If the path consists of only line segments this self-intersection test is
easy: check for a bounding intersection (with QLineF::intersect) between all
non-adjacent segments.

If the path also contains arced segments I have no idea how I should check
for intersections. I was kind of hoping the existing QPainterPath API
already has something to solve this.

Many thanks in advance!
Greets,


        Ben

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