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<p class=MsoNormal><span style='color:#1F497D'>Hi,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>A different approach is to
create functions which takes a geometry and an enumeration, this way each
provider can implement all cases or just a few of them, e.g.:<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>PointX(geom, enum)<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>PointY(geom, enum)<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>PointZ(geom, enum)<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Where enum can be: ‘start’, ‘end’,
‘min’, ‘max’, ‘</span><span style='color:#1F497D'>centroid’</span><span
style='color:#1F497D'>, …<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>For now we may implement just a
few of them (start, end) and in the future we could implement more cases.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Romy.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> fdo-internals-bounces@lists.osgeo.org
[mailto:fdo-internals-bounces@lists.osgeo.org] <b>On Behalf Of </b>Maksim
Sestic<br>
<b>Sent:</b> Tuesday, November 04, 2008 10:28 AM<br>
<b>To:</b> 'FDO Internals Mail List'<br>
<b>Subject:</b> RE: [fdo-internals] Request review of RFC 28 -AddStart/EndExpressionFunctions<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:blue'>Hi Orest,</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:blue'>I agree, but I presume these functions will get
implemented out of necessity - i.e. original RFC author definately had
something in mind while suggesting PointX/Y or StartX/Y functions... and it's probably
tied to labeling (Map, MapGuide). If this is the case, then functions can get
adopted to fit that specific purpose. I agree it's a slippery
slope there, easily slipping to stylization issues etc :-)</span><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<div>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:blue'>Regards,</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:blue'>Maksim Sestic</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
</div>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p> </o:p></span></p>
<div class=MsoNormal align=center style='text-align:center'><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>
<hr size=2 width="100%" align=center>
</span></div>
<p class=MsoNormal style='margin-bottom:12.0pt'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> fdo-internals-bounces@lists.osgeo.org
[mailto:fdo-internals-bounces@lists.osgeo.org] <b>On Behalf Of </b>Orest
Halustchak<br>
<b>Sent:</b> Tuesday, November 04, 2008 16:00<br>
<b>To:</b> FDO Internals Mail List<br>
<b>Subject:</b> RE: [fdo-internals] Request review of RFC 28
-AddStart/EndExpressionFunctions</span><span style='font-size:12.0pt;
font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Hi,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Maksim, these are good ideas,
and there are all kinds of geometry type functions that we could add such as
your AngleXY() example – centroid, mbr, buffer, etc. We already have length and
area.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>However, the purpose of this RFC
is for a basic set of functions to help with displaying coordinate values in a
data table type report, so expanding it to a lot of other things would be
beyond the scope of what we wanted to build at this time. I think if folks find
these other functions useful (and I agree that they are useful), my suggestion
is to create a new RFC for them.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>For the simple point function,
it looks like we have the following ideas (extrapolating a bit from the
discussion):<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in'><span style='font-family:
Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;font-family:"Times New Roman","serif";
color:#1F497D'> </span><span
style='color:#1F497D'>StartX(geom), StartY(geom), etc.<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in'><span style='font-family:
Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;font-family:"Times New Roman","serif";
color:#1F497D'> </span><span
style='color:#1F497D'>PointX(geom), PointY(geom), etc.<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in'><span style='font-family:
Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;font-family:"Times New Roman","serif";
color:#1F497D'> </span><span
style='color:#1F497D'>PointX(geom, n), PointY(geom, n), etc.<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in'><span style='font-family:
Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;font-family:"Times New Roman","serif";
color:#1F497D'> </span><span
style='color:#1F497D'>MinX(geom), MinY(geom), MaxX(geom), etc.<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in'><span style='font-family:
Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;font-family:"Times New Roman","serif";
color:#1F497D'> </span><span
style='color:#1F497D'>CentroidX(geom), CentroidY(geom)<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>The startx/endx type functions
have issues related to what they mean for polygons and multi-type geometries.
They make sense for line and point geometries. For a single polygon loop, they
sort of make sense.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>The pointx/pointy type functions
are fine for points, but don’t have meaning for other geometries unless we treat
them as centroid. I’d rather avoid defining functions that throw exceptions for
a large number of geometry types if we can. My preference would be to have a
defined result for all geometry types if at all possible.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>The pointx(n) type functions are
more useful in general that starx/endx type functions, but have the same issue
around what they mean for polygons and multi-type geometries.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>The minx/miny type functions
work for all geometry types, but require extra processing than just grabbing an
existing point form the geometry object.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>The centroidx/centroidy type
functions also work for all geometry types, but also require extra processing.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Orest.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
fdo-internals-bounces@lists.osgeo.org
[mailto:fdo-internals-bounces@lists.osgeo.org] <b>On Behalf Of </b>Maksim
Sestic<br>
<b>Sent:</b> Tuesday, November 04, 2008 3:08 AM<br>
<b>To:</b> 'FDO Internals Mail List'<br>
<b>Subject:</b> RE: [fdo-internals] Request review of RFC 28 -
AddStart/EndExpressionFunctions<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:blue'>Why don't you introduce optional parameter for vertice index being
inspected, i.e. PointX(n) - if there's no parameter then value of 0 is assumed
(used with Point geometries). In that way one can evaluate
linestring and polygon single vertice coordinate.</span><span style='font-size:
12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:blue'>I think there's something else missing - I'm trying to draw
directions for one-way roads, as in Google Earth/Map. Although each road
network's linestring is directed (as in directed graph) and has direction flag
attached (uni/bi-directional), I still don't have enough data to actually
rotate an arrow - depicting road direction. How about introducing AngleXY() and
AngleXY(n) functions returning line segment angle in plane? Is there any other
solution to this, except for storing pre-calculated vectors? Maybe adding some
additional stylization rule for this?</span><span style='font-size:12.0pt;
font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:blue'>Regards,</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";
color:blue'>Maksim Sestic</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p> </o:p></span></p>
<div class=MsoNormal align=center style='text-align:center'><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>
<hr size=2 width="100%" align=center>
</span></div>
<p class=MsoNormal style='margin-bottom:12.0pt'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> fdo-internals-bounces@lists.osgeo.org
[mailto:fdo-internals-bounces@lists.osgeo.org] <b>On Behalf Of </b>Traian
Stanev<br>
<b>Sent:</b> Monday, November 03, 2008 23:40<br>
<b>To:</b> FDO Internals Mail List<br>
<b>Subject:</b> RE: [fdo-internals] Request review of RFC 28 -
AddStart/EndExpressionFunctions</span><span style='font-size:12.0pt;font-family:
"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Yeah, may be just provide
PointX()/PointY()/PointZ() functions which take a geometry as argument and
throw an error for anything but points?<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Traian<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
fdo-internals-bounces@lists.osgeo.org
[mailto:fdo-internals-bounces@lists.osgeo.org] <b>On Behalf Of </b>Dan Stoica<br>
<b>Sent:</b> Monday, November 03, 2008 5:24 PM<br>
<b>To:</b> FDO Internals Mail List<br>
<b>Subject:</b> RE: [fdo-internals] Request review of RFC 28 - Add
Start/EndExpressionFunctions<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='color:#1F497D'>What has the Start point so
special except for the point features? For example, the START=END for simple
polygons. <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Maybe this ECO should address
only points? <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Dan.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
fdo-internals-bounces@lists.osgeo.org
[mailto:fdo-internals-bounces@lists.osgeo.org] <b>On Behalf Of </b>Greg Boone<br>
<b>Sent:</b> Monday, November 03, 2008 2:53 PM<br>
<b>To:</b> FDO Internals Mail List<br>
<b>Subject:</b> RE: [fdo-internals] Request review of RFC 28 - Add
Start/EndExpressionFunctions<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='color:#1F497D'>Yes, Lines and Polygons do offer
some difficulties. Also, the multi-geometry objects are also a little weird. I
am open to suggestions on how to handle these types.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Greg<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
fdo-internals-bounces@lists.osgeo.org
[mailto:fdo-internals-bounces@lists.osgeo.org] <b>On Behalf Of </b>Jason Birch<br>
<b>Sent:</b> Thursday, October 23, 2008 12:34 PM<br>
<b>To:</b> FDO Internals Mail List<br>
<b>Subject:</b> RE: [fdo-internals] Request review of RFC 28 - Add
Start/EndExpressionFunctions<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>That makes sense to
me; I just wasn’t sure what you would use the equivalent function for
lines/polygons for.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-CA style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>Jason <o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-CA style='color:#1F497D'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Robert Fortin<br>
<b>Subject:</b> RE: [fdo-internals] Request review of RFC 28 - Add Start/EndExpressionFunctions<o:p></o:p></span></p>
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<p class=MsoNormal><span lang=EN-CA><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#993366'>The use case: presents the
ordinates of a point geometry as attribute in a data table. This feature
will help us achieve that.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#993366'>You could also think it can be
used to display the coordinate as labels as part of the symbology of a feature.
<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#993366'>Or you could use the StartZ to
show the elevation of a point or apply a theme on it.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#993366'>All these can’t be done easily
directly using the geometry attribute.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><br>
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