Re: [PyX-devel] Two other things that might be nice...

[Andre W. <wo...@us...>]

Hi,

On 29.07.04, Magnus Lie Hetland wrote:
> CAG is a 2D-version of constructive solid geometry. Basically the use
> of set operations on areas (or closed (or, perhaps, even open?)
> paths). The Java 2D API has it (although I've never really used that
> much).
> 
> Basically you can do stuff like "take this circle here, remove the
> part that overlaps with this other circle here, and then use the union
> of that and this rectangle here" and so forth. Can make it quite easy
> to build up complex paths.

Sounds like something to be build finite size canvas aka canvas with a
border aka boxes (in the future). I'll try to keep it in mind.

> > >   - Transparency/alpha levels (has been done using MetaPost; could
> > >     perhaps be ported)
> > 
> > Transparency in PostScript? Have to take a look at it. I know that
> > there are some tricks, but those are quite problematic.
> 
> Sure. Here's some material on faking transparency with MetaPost,
> though:
> 
>   http://www-math.univ-poitiers.fr/~phan/metalpha.html

I.e. you calculate yourself what curves/colors occur when a partially
transparent objects is painted on to of some existing material. You're
free to do so. Well, its more difficult than in MetaPost I guess.

> > I'm sorry, what's SVM?
> 
> Dang. It's "support vector machine", but that's not what I meant to
> say (I'm just used to typing it).

As I found out myself before ...

About SVG: Its already on the TODO list (for about half a year or so).
This means, yes, SVG support would be great. Its something we should
try to implement to catch up with the future.

> But I guess supporting lots of output formats isn't all that useful,
> really, as long as there are converters out there.

I'm not that sure. Why do you use pdftex instead of TeX+dvips+ps2pdf?
Why is there even a market share for such a program like pdftex?

> Perhaps one could add a back-end for different output formats, and use
> command-line converter tools per default, until custom output routines
> were produced?

Personally I'm not convinsed to make use of external programs to claim
to support pdf, png, gif, jpeg etc. output. It's just a lie.

> Or perhaps a simple drawing API could be used at the bottom, and
> several back-ends could be used... (Hm. Drifting back to my old
> project PIDDLE here, I guess ... ;)

Well, we don't have bitmap output and PyX isn't designed that way to
support it even in the far future. Our objects know themselfs what
they need to do in order to be inserted into a vector graphics format
like PostScript, PDF, etc. ... so it's not like PIDDLE. Anyway, we
need to extract, what special features are in those different vector
graphic formats we want to support and try to fit it into a unique
API. Things like strokecolors and fillcolors, which PDF has, but
PostScript doesn't. I think (Jörg and I discussed it), we want only
one color for both, stroking and filling. Just to give you an idea,
what we're thinking about and what our problems are ...

In the end it's clear that PostScript, PDF and SVG are close enough to
at least dream about support them all. In that sense we restrict
ourself to quite a limited scope ...


André

-- 
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