octave-bug-tracker
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Octave-bug-tracker] [bug #53397] Delaunay returns inconsistent (cw/ccw)


From: jsh
Subject: [Octave-bug-tracker] [bug #53397] Delaunay returns inconsistent (cw/ccw) orientations in 2d
Date: Tue, 20 Mar 2018 21:48:33 -0400 (EDT)
User-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0

URL:
  <http://savannah.gnu.org/bugs/?53397>

                 Summary: Delaunay returns inconsistent (cw/ccw) orientations
in 2d
                 Project: GNU Octave
            Submitted by: jsh
            Submitted on: Wed 21 Mar 2018 01:48:31 AM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.2.2
        Operating System: Any

    _______________________________________________________

Details:

In Octave the delaunay/delaunayn function calls returns inconsistent (both
clockwise and counter-clockwise) orientations in 2d, while Matlab seems to
return only counter-clockwise oriented triangulations:


p = [0 0;1 0;1 1;0 1;.5 .5]
t = delaunay( p );

d12 = p(t(:,2),:) - p(t(:,1),:);
d13 = p(t(:,3),:) - p(t(:,1),:);
a = ( d12(:,1).*d13(:,2) - d12(:,2).*d13(:,1) )/2;

is_clockwise = a<0       


This can easily be fixed in post triangulation with


t(is_clockwise,2:3) =  t(is_clockwise,[3,2]);


but it could be good to make it consistent and built-in by default.







    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?53397>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/




reply via email to

[Prev in Thread] Current Thread [Next in Thread]