[postgis-users] AsSVG() and precision control

[strk at refractions.net]

Ok. I've added a specific function to trim trailing zeros and dots
in LWGEOM. assvg() now has its original precision semantic (number
of decimal digits) w/out the 0 padding.
postgis-0_9 branch does not have this change (yet?).
--strk;

On Fri, Oct 15, 2004 at 10:49:18AM +0200, strk at refractions.net wrote:
> On Thu, Oct 14, 2004 at 12:26:44PM +0200, Klaus Foerster wrote:
> > >Your patch does not do what reported:
> > >Precision defaults to 15, so you need to give it an explicit negative
> > >number for the %g to take effect. Default would be 0 padded numbers.
> > sorry, forgot about that - http://svg.cc/pg/assvg/assvg-0.5.1.patch solves
> > that issue by setting default precision to -1 and using %.15g or %.*f
> > accordingly.
> 
> I don't like this either.
> Maybe we should always use %f and *manually* remove trailing zeros.
> What do you think ?
> --strk;
> 
> > 
> > >What I see is that the problem only arises for relative moves, where
> > >number of significant digits wants to be different between absolute
> > >and relative values.
> > well, absolute notation might be affected as well. what about a coordinate
> > pair like 241034.194490223,5610355.30134846 ? if you reduce output to seven
> > digits you start mixing coordinate precision as x-coordinates originally 
> > have 6,
> > and y-coords 7 digits to the left - 241034.2 -5610355 would be the result.
> > 
> > >A proposal I can make is that:
> > >
> > >	- On "absolute" are requested all values will have 'precision'
> > >	  number of significant digits
> > >
> > >	- On "relative" way initial (absolute) values will have 15
> > >	  significant digits, and relative values will have 'precision'
> > >	  number of significant digits.
> > >
> > >Do you think this would solve the problem ?
> > i think absolute and relative notation should be treated the same way. 
> > please give
> > my latest patch a try - i do think it now does what i intended to 
> > accomplish ;-)
> > i've also updated http://svg.cc/pg/assvg/1_output.txt to reflect the change.
> > 
> > klaus
> > 
> > -- 
> >          O-.
> >          /_ )
> >           | (U
> > klaus*   /|
> >         / /
> >         ~ ~
> > 
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