RE: [cgmo-webcgm] Compound Line Element?

["Cruikshank, David W" <david.w.cruikshank@boeing.com>]

BoGART currently uses Closed Figure to group what internally we call a "polyspline".  It's really not a closed figure and really is a Compound Line.  We did that because we didn't think there was much support for the element.

I'll put together a test file and do some testing.  The question is whether the visual effect is still there (ie do I get the line segments in the view or does everything get dropped).

We also use Closed Figure to group a polyspline that that has different attributes on the line segments (line type, edge visibility, etc.)  Line attribute elements are not allowed in Open Path state, so Closed Figure is the only way to do it.  We've run into some interop issues with that (particularly edge visibility) so will probably drop the invisible sections and just put out individual line elements.  I think this was the gist of the CGM V5 discussion w.r.t. Compound Line.

thx...Dave

-----Original Message-----
From: Lofton Henderson [mailto:lofton@rockynet.com]
Sent: Tuesday, June 22, 2004 10:47 AM
To: Cruikshank, David W
Cc: CGM Open WebCGM TC
Subject: Re: [cgmo-webcgm] Compound Line Element?


At 03:52 AM 6/22/2004 -0700, Cruikshank, David W wrote:
>Do anyone have an example file that uses Compound Line?  We are thinking 
>of implementing it and are wondering about whether there is support for it 
>out there..

Since it is allowed in ATA grex, I went looking for it in the old ATA CGM 
test suite.  Not there!  Interesting oversight, as the implementation and 
test cases would be no harder than Closed Figure.  In fact, it would 
probably be fairly easy to adapt WebCGM test cases FIGUR01 and FIGUR02.

Question (all):  Does anyone implement and use Compound Line?  (I can't 
remember whether or not our old HSI viewers did it.)

Question (Dave):  What do you anticipate to use it for?

Question (all):  Does anyone remember the details of some recent discussion 
about line/edge attributes and Compound Line or Closed Figure?  Was it at 
Cologne, in the context of possible CGM V5 revisions?

Regards,
-Lofton.