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RE: More on getObjectExtent()

From: Lofton Henderson <lofton@rockynet.com>
Date: Wed, 19 Nov 2008 09:04:24 -0700
Message-Id: <>
To: "Bezaire, Benoit" <bbezaire@ptc.com>, "WebCGM WG" <public-webcgm-wg@w3.org>
At 09:26 AM 11/19/2008 -0500, Bezaire, Benoit wrote:
>I think the wording should be revised.

Fair enough.

>Even Google doesn't come up with anything meaning full for "Abstract locus".

However, it does give lots of hits for a search like "definition of 
mathematical locus".  And we use "locus" repeatedly, in the proper sense, 
in the profile (Ch.6) -- i.e., "locus" is a pretty common term in  and has 
been used in WebCGM, for example, since 1999.  So it is my hastily-invented 
modifier "abstract" that is problematic.

Actually, I think a good solution would be to drop the word 
"abstract".  The next sentence after its occurrence fully explains what 
"abstract" was meant to convey.  (And we have agreed to clarify that sentence.)

(See the getObjectExtent definition in 5.7.6:
http://docs.oasis-open.org/webcgm/v2.1/cs01/WebCGM21-DOM.html#L5095 .)


(Shall I just add this to fix to the clarification in DoC #3:
http://www.w3.org/Graphics/WebCGM/WG/2008/WebCGM21-LC-comments.html#Issue3  ?)


>From: Lofton Henderson [mailto:lofton@rockynet.com]
>Sent: Tuesday, November 18, 2008 6:52 PM
>To: Bezaire, Benoit; WebCGM WG
>Subject: Re: More on getObjectExtent()
>At 01:52 PM 11/18/2008 -0500, Bezaire, Benoit wrote:
>>The wording says "[...] The bounding box calculation is based on the 
>>abstract locus of the primitives within the APS."
>>What does 'abstract locus' mean?
>The locus is the set of points comprising the drawn primitive (it's a term 
>I dredged up from my memory of some old math courses -- I hope I got it 
>right).  "Abstract locus" means that things like line width are not 
>included, but rather only the point positions as if the item were drawn 
>with an abstract, infinitely fine pen.
>>I'd like to know if getObjectExtent() returns a tight bounding box on a 
>>given APS. i.e., given a polybezier, are control points part of the 
>>bounding box calculations or not?
>No.  The control points are part of the defining data, but not part of the 
>drawn primitive.
Received on Wednesday, 19 November 2008 16:05:24 UTC

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