[poppler] Patch proposal: Implementation for real gouraud shaded triangles

[Albert Astals Cid]

A Dijous, 19 d'agost de 2010, vàreu escriure:
> Dear Albert,
> 
> attached you find a test.pdf in which the improvements can be seen.
> 
> The rendering quality of my patch is much better; it eliminates the
> moire effects of the flat shading approximation (top left image).
> 
> Compare also the image with opacity on page 2 of test.pdf.
> 
> Besides the improved rendering quality, the most obvious change is the
> required runtime: on my system, the default xpdf requires 15 seconds
> until it stops rendering the first page whereas xpdf with poppler
> support and my new patch requires about one second. The pdftoppm utility
> is also considerably faster.
> 
> Let me stress that the patch is unrelated to my previous bugfixes, so
> rendering problems are only fixed together with the other bugfix.

I'm not sure i understand this last sentence, you say that the patches are 
unrelated but then you say the bugs are only fixed together with the other 
patch?

Should i run a regression test over this patch or does it need to be in 
conjunction with the other patch?

Albert

> 
> Best regards
> 
> Christian
> 
> Am 18.08.2010 23:15, schrieb Albert Astals Cid:
> > A Dijous, 15 de juliol de 2010, Christian Feuersaenger va escriure:
> >> Dear poppler developers,
> >> 
> >> hereby I propose a new patch for a high quality, fast gouraud shader for
> >> triangle shadings.
> >> 
> >> The patch provides
> >> - scalable triangle shadings (in contrast to the old approach),
> >> - correct shading, no approximation using flat triangles,
> >> - greatly (!) improved rendering speed,
> >> - support for opacity (in contrast to the previous approach).
> >> 
> >> This patch is relative to the master branch,
> >> git show poppler-0.14.0-91-g31ac578 .
> >> 
> >> It is unrelated to my previous patch proposals concerning shadings; the
> >> other patch proposal (my mail several weeks ago) is still important and
> >> relevant. The patch in this mail is independent and does not include my
> >> previous patch proposals.
> >> 
> >> I tested the new patch with pdftoppm and with the xpdf-poppler fork of
> >> Rogerio Brito; it appears to work reliable. I tested
> >> - matrix shadings and triangle patch shadings (Types 4 and 5),
> >> - degenerated triangles,
> >> - clipping,
> >> - opacity,
> >> - RGB color spaces.
> >> 
> >> The implementation now supports these shadings on a display driver level
> >> and is implemented directly in the splash device (using scanline
> >> sweeps).
> >> 
> >> I've been defensive: I have no test cases for other color spaces and I
> >> have no test data for non-parametric shadings. Consequently, I disabled
> >> the shader for these cases; it will fall back to the existing solutions
> >> (approximate shading by means of many flat triangles).
> >> 
> >> I hope you find my patch proposal useful. I believe it is worthy of
> >> being part of libpoppler.
> > 
> > Do you have a pdf where we can see the improvement this patch gives?
> > 
> > Albert
> > 
> >> Thanks,
> >> 
> >> Christian
> > 
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