[GRASS-dev] Cairo monitor driver

[Glynn Clements]

Hamish wrote:

> > One of the main areas where this is relevant is if we want translucent
> > layers. It's possible to simulate translucency in PostScript using
> > pattern fills, but you need to be careful when selecting the grid
> > (frequency, phase, orientation) or else you can get artifacts.
> 
> Older versions of Surfer (the commercial 3D surface rendering program) that I
> have used do that for area fills- shades of grey are many dots of varying
> density. The PS output is a massive file which takes a silly amount of time to
> render in gv and is generally an all-around PITA to work with.  (meant as an
> anecdote, not as a condemnation of the approach)

That's just Surfer generating bad PostScript; it's probably
"capturing" its rendering at a low level, resulting in vast numbers of
individual "dots" being stored in the stream.

Level 2 PostScript supports a pattern "colour space", which allows you
to use a pattern as the fill colour. However, this can't be used for
painting images (this may be related to the similar restriction for
PDF; it would be interesting to see the PostScript generated when
printing such a PDF).

-- 
Glynn Clements <glynn at gclements.plus.com>