[comp.lang.postscript] Questions on Fill patterns ...

lee@mit-caf.MIT.EDU (Lee Tavrow) (11/18/88)

--text follows this line--

hi.

I am trying to generate fill or stipple patterns in postscript.  The
ps cookbook shows you a way to do this.  The problem is that I
want the overlapping fill patterns to be "or"ed together instead of
the top pattern completely erasing the bottom one.  For example, I
want:

  x   x   x   x              x   x   x   x          x   x   x   x
   x   x   x                x   x   x   x          x x x x x x x x
    x   x   x      over    x   x   x   x   ==>    x   x   x   x   x
 x   x   x   x            x   x   x   x            x x x x x x x x 

etc...

The only command that I could find in the ps manual which did something
vaguely related was "imagemask" instead of "image" where "imagemask"
is transparent, as the manual says.

Any ideas??????

Also, does anyone know how to give poscript a bunch of overlapping
polygons and have postscript spit back a path which is the outline
of the polygons?????

Please send mail directly to me (in addition to this file if you want to)

thanks in advance,
lee

greid@adobe.com (Glenn Reid) (11/19/88)

> I am trying to generate fill or stipple patterns in postscript.  The
> ps cookbook shows you a way to do this.  The problem is that I
> want the overlapping fill patterns to be "or"ed together instead of
> the top pattern completely erasing the bottom one.  For example, I
> want:

The example in the Green Book uses font characters instead of the
"image" operator to accomplish pattern fills.  Among other advantages,
the patterns themselves are inherently "transparent", since font
characters work like "stroke" or "fill", and do not write the white
bits.  Give it a try.  Note that there is a "patternfill" and an
"opaquepatternfill" procedure defined.  The opaque version just fills
the region with "1 setgray" before it fills it with pattern.  Take your
pick.

I hope this helps....

Glenn Reid
Adobe Systems

P.S.  The green book programs are available through our file server,
although you still need the book to make much sense of them.  It does
save typing them in, however, and they are debugged :-).  Send a message
to "ps-file-server@adobe.COM" containing the text
"send Programs greenbook.shar"