Sounds like a good solution to the issue, what about the existing
SimplifyingVisitor and other simplifiable functions like Add and Subtract,
will you add it to them or is that left as further work?
Ian
On Thu, 30 Nov 2023 at 21:47, Jody Garnett <jody.garn...@gmail.com> wrote:
> What a fun problem, I think the suggestion is a good one.
>
> On Fri, Dec 1, 2023 at 2:31 AM Andrea Aime <
> andrea.a...@geosolutionsgroup.com> wrote:
>
>> Hi,
>> I'm working with wind maps, where typically the data contains
>> (some way to compute) magnitude and directions of the wind vectors.
>>
>> Now, the "direction" is an angle that is used to rotate a symbol.
>> The angle has an assumption... that north is up. However, take a non
>> trivial projection, like polar ones, and the assumption goes belly up, the
>> direction of north can change point by point.
>>
>> So my plan is to introduce a function, "northFix", that would provide a
>> correction angle
>> taking as parameters a CRS and the current point. Something like this:
>>
>> <Rotation>
>> <ogc:Function name="northFix">
>> <ogc:Literal>EPSG:3976</ogc:Literal>
>> <ogc:PropertyName>theGeom</ogc:PropertyName>
>> <ogc:PropertyName>windDirection</ogc:PropertyName>
>> </ogc:Function>
>> </Rotation>
>>
>> Parameters in order:
>>
>> - The current CRS (in actual app, coming from an env variable, e.g
>> "wms_crs" in GeoServer)
>> - The current point
>> - The angle to be fixed
>>
>> So far, so good, I'd say... but in a general SLD, that might still eat
>> quite some time, in cases where it's not needed, e.g., web mercator, WGS84.
>> It would be better to recognize the situation right away, and eliminate the
>> function, replacing it with the wind direction property name directly.
>>
>> I have a StyleSimplifier that could do that, but it would also be quite
>> ad-hoc. Could we have maybe an interface that functions could implement to
>> test if they are simplifyable at all, and offer a replacement? E.g.
>>
>> SimplifyableFunction {
>> Expression simplify(Function function);
>> }
>>
>> Thoughts?
>>
>> Cheers
>> Andrea
>> ==
>>
>> GeoServer Professional Services from the experts!
>>
>> Visit http://bit.ly/gs-services-us for more information.
>> ==
>>
>> Ing. Andrea Aime
>> @geowolf
>> Technical Lead
>>
>> GeoSolutions Group
>> phone: +39 0584 962313
>>
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>>
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>>
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>>
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Ian Turton
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