Re: More on getObjectExtent()

Since not everyone is satisfied with the simple fix of "s/abstract 
locus/locus/" in 5.7.6, I'll make a proposal to close the "locus" 
issue:  delete the word "abstract" and link "locus" to a glossary entry.

Here is a first draft proposal:

[[[
locus --
The Oxford dictionary defines locus as:  "Curve formed by all points 
satisfying particular equation of relation between coordinates, or by 
point, line, or surface, moving according to mathematically defined 
conditions."  In the WebCGM specification, locus refers to the set of 
points that comprise the path or shape of a Graphical Primitive element, or 
in the appropriate context, the combined shapes or paths collectively of 
all of the Graphical Primitive elements in an Application Structure 
(APS).  I.e., the locus of an APS comprises the combined loci of all of the 
graphical primitives in the APS.  Locus does not include defining data that 
are not part of the shape or path of the graphical primitive, such as 
control points of Bezier primitives, or the center point of a Circular Arc 
Center primitive.
]]]

Question 1:  Are people okay with the solution of adding a definition to 
the Glossary?

Question 2:  Suggestions for improvement of the definition?

-Lofton.



At 09:45 AM 11/19/2008 -0700, Lofton Henderson wrote:
>Dave,
>
>At 08:32 AM 11/19/2008 -0800, David Cruikshank wrote:
>>I would agree with dropping "abstract".  Locus is a perfectly valid term 
>>to define the path of the primitive.
>>
>>Probably ought to capture it somewhere to document the decision.
>
>Just to clarify that last sentence -- you mean that you support the issue 
>processing proposal to roll it into Issue3 in the DoC (see URI below)?
>
>Thanks,
>-Lofton.
>
>
>>On Wed, Nov 19, 2008 at 8:04 AM, Lofton Henderson 
>><<mailto:lofton@rockynet.com>lofton@rockynet.com> wrote:
>>>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>http://docs.oasis-open.org/webcgm/v2.1/cs01/WebCGM21-DOM.html#L5095 
>>>.)
>>>
>>>Okay?
>>>
>>>(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>http://www.w3.org/Graphics/WebCGM/WG/2008/WebCGM21-LC-comments.html#Issue3 
>>>?)
>>>
>>>-Lofton.
>>>
>>>
>>>>
>>>>----------
>>>>From: Lofton Henderson 
>>>>[<mailto:lofton@rockynet.com>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.
>>>>
>>>>-Lofton.