[squeak-dev] Re: Bezier filled shape rendering artifacts
gazzaguru2 at btinternet.com
Tue Mar 25 11:45:48 UTC 2008
I have noticed that the rendering is significantly improved for your example
when scaled by a factor of 20, leading me to believe that Balloon has a
precision problem with small values and/or the fact that the minimum line
width is 1, regardless of any transform that may be in effect.
> -----Original Message-----
> From: squeak-dev-bounces at lists.squeakfoundation.org
> [mailto:squeak-dev-bounces at lists.squeakfoundation.org]On Behalf Of Klaus
> D. Witzel
> Sent: 25 March 2008 7:28 AM
> To: squeak-dev at lists.squeakfoundation.org
> Subject: [squeak-dev] Re: Bezier filled shape rendering artifacts
> On Tue, 25 Mar 2008 03:48:01 +0100, Igor Stasenko wrote:
> > On 25/03/2008, Klaus D. Witzel wrote:
> >> > I don't know why this particular glyph not rendered correctly, i can
> >> > only suppose that it
> >> > was defined with sequence of data, which wrongly parsed by SVGMorph.
> >> > Why i think it's not engine? Because engine can't twist point
> >> > coordinates of shape, it can only fail to fill shape
> correctly. And
> >> in
> >> > this glyph i see twisting coordinates, look like somewhere SVG morph
> >> > starts feeding engine with wrong coordinates.
> >> Huh? I've spent hours checking Gary's parsing code (before posting
> >> anything here in squeak-dev) and until now saw [said the
> possibly blind
> >> man] no wrongdoing (even compared to a Javanese implementation which
> >> has
> >> no rendering bug). Some typos in SVGMorph's parsing method, quadratic*
> >> v.s. qubic*, but these lines wheren't used especially for
> >> (which I tested most).
> >> So you found something suspicious; please tell what and where (did you
> >> mean in Y4.svg?). I could use a point where to start
> debugging from. In
> >> which segment did you see twisted coordinates? TIA.
> > Yes, if i find something suspicious, i'll let you know.
> > In attachment is a comparable rendering results from Opera (gray) and
> > SVGMorph (black).
> Great (except that the colors render here as redish and grayish), thanks
> much !
> > Looks like i was wrong about twisting - the glyph is so small that its
> > hard to say what is there, unless you zoom it in.
> Yeah that's what makes the 'S' in SVG indispensable :)
> > I think you can try to remove drawing parts/segments step by step from
> > original svg to see where it breaking. And then you can trace why.
> Don't ask me how often I have already done that (in the segment assembly
> method) but, it didn't turn up anything buggy ...
> Nevertheless let me thank you for standing by me; often it's just
> the "you
> are not alone" strategy which kills the insect :)
> Will now focus on the areas you colored in the .jpg, thanks again.
> P.S. the more I think about this problem the more it smells like the
> path/line/beziers do not flush the engine appropriately (similiar
> to what
> you corrected and to what Gary commented last night).
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