CGAL users discussion list

[John Carter <>]

Greetings,

 

As a first time CGAL user, I’d like to greet the users and thank the community for this great piece of software.

 

While sifting through the code to build a polygonal medial axis transform using a Segment_delaunay_graph,  I noticed what appears to be a bug in one of the draw functions.

 

I am using CGAL 3.8, Visual Studio 10.0 Premium, and Windows 7 with the Filtered_kernel, and Simple_cartesian<double> coordinates.

 

The function for drawing a parabolic edge segment to a stream does not properly output a space, causing adjacent line segments to be merged into the stream incorrectly.  An example of the buggy output for an edge:

 

79.4211 133.286 79.4211 133.28679.4211 133.286 63.5996 134.11363.5996 134.113 58

 

As can be seen, “133.28679.4211” should read “133.286 79.4211”.

 

Although there might be a better way to do it, I implemented a simple fix which seems to work:

 

In Parabola_segment_2.h line 155 in the draw(Stream& W) function:

 

The line was changed from:

 

W << Segment_2(p[i], p[i+1]);

 

To :

 

W << Segment_2(p[i], p[i+1]) << “ “;

 

I’m not entirely sure why a space is output between some of the coordinates and not others, but this fixed the problem for me.  I thought it would be worth pointing out if other people have had problems with this in the past.

 

Regards,

John Carter

GeoDigital International Corp.