Jody Garnett ha scritto:
> Hey Andrea;
> 
> I am still trying to figure out what your optimization did ...
>> Years ago, way before my involvement in GeoServer, I
>> introduced a rendering optimization for lines. The
>> observation was that if the line width was less than
>> 1.5 pixels, setting it to 0 flat would make the rendering
>> quite a bit faster (30%+ if my memory serves me right)
>> and the visual result would have been the same.
>>   
> This magic number of 1.5 only makes sense if anti-alias is turned off 
> right. To keep in the spirit of the optimization
> it should be set to 1.25 (if we assume 4x subsampling); or turned off 
> completly if anti-aliasing is turned on?

It should be turned off completely. But judging from you comments
there must be some misunderstanding.

The two samples I've attached for each map are both drawn with
antialiasing turned on. The one with "thin lines" is what
we are drawing today, without me touching the code.

The one with the thick lines is instead the code running
without that old optimization. The SLD is exactly the same,
but it should be easy to see that the rendered line is easily
twice as thick.

Now what do you think will happen when uDig users discover all
of their maps render differently, and they have no way to
change them back? In GeoServer people can change the SLD
to force a 0.5 pixels line width and they get pretty much
the same result as before.

But in uDig, the UI does not allow you to enter 0.5 as
the value for a line width.
This is the kind of change that makes people do work only
to get back what they already have, so expect some pissed
off people. That's why I'm trying to take a soft change
path in GeoServer, so that people that do have fine control
of their line width can, but everyone else can happily
keep moving along without noticing (at least for some
time).

Cheers
Andrea

-- 
Andrea Aime
OpenGeo - http://opengeo.org
Expert service straight from the developers.

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