Re: [Groff] pic: how to fill a diamond shape?

[Louis Guillaume]

(Ted Harding) wrote:
> .PS
> box wid 2 ht 2 at (0,0)
> "\v'-0.22m'\D'p 1i -1i 1i 1i -1i 1i -1i -1i'" at (-1,0)
> box wid 2 ht 2 at (0,-3)
> "\v'-0.22m'\D'P 1i -1i 1i 1i -1i 1i -1i -1i'" at (-1,-3)
> .PE
> .sp
> .LP
>
>
> where "\v'-0.5n'" has been replaced by "\v'-0.22m'". This was
> based on looking at the 'pic' output for
>
> .PS
> line right "xxx"
> .PE
>
> where I saw:
>
> \h'0.000i'\v'0.000i'\D'l0.500i 0.000i'
> .sp -1
> .lf 2
> \h'0.250i-(\w'xxx'u/2u)'\v'0.000i-(0v/2u)+0v+0.22m'xxx
>
> It's still an empirical rather than a principled solution,
> but at least it is based on better evidence!
>
> Ted.


Thank you for this, Ted. It is very strange and I can't seem to figure 
out what's going on beyond the 0.22m "adjustment". So (still using 
empirical methods) here's what I'm seeing...

.PS

"\D'Fr #ddffdd'"
"\D'P 1i -0.5i 1i 0.5i -1i 0.5i -1i -0.5i'"

.PE

This gives me a nice green diamond (or kite, I think). It's left point 
is centered on the page and everything appears to look good. Because 
after all we did draw to the right and we are starting in the middle 
(pic's default). One would expect the current point after the drawing to 
be on the left point of the kite... but it isn't.

The kite has been rendered off vertically by 0.22m (above) as you've 
pointed out. I guess  pic knows about this and makes the adjustment 
appropriately when drawing shapes.

So I need to adjust the kite's position up by 0.22m to meet the current 
point.

.PS

"\D'Fr #ddffdd'"
"\v'-0.22m'\D'P 1i -0.5i 1i 0.5i -1i 0.5i -1i -0.5i'"
arrow down

.PE

The arrow starts precisely on the left point. Nice!

Ok now Let's move the whole deal over by 1 inch so we can have the thing 
centered nicely...


.PS

"\D'Fr #ddffdd'"
"\v'-0.22m'\h'-1i'\D'P 1i -0.5i 1i 0.5i -1i 0.5i -1i -0.5i'"
move down 0.5i
arrow down

.PE

.... AAA!! It only moves over 1/2". If I move it over by 2 inches it 
lines up as I want it to. So the \h is cut in half for some (unknown to 
me) reason.

The polygon we created does not have the normal pic attributes that we 
can refer to. My original kite with lines and a box was ok, but I think 
that since the polygon isn't drawn with pic, we can't refer directly to 
the n,s,e,w etc. points on the object.

What I'm stuck doing is referring to the box within my "decision()" 
function. Not ideal, but workable.

.PS

define decision {
  move down 0.5i
  "\D'Fr #ddffdd'"
  "\v'-0.22m'\h'-2i'\D'P 1i -0.5i 1i 0.5i -1i 0.5i -1i -0.5i'"
  move down 0.5i
  "\v'-0.22m'\D'p -1i -0.5i 1i -0.5i 1i 0.5i -1i 0.5i'"
  up
  DBOX: box wid $1 ht $2 invis $3
}

down
circle "start"
arrow
decision(2,1,"Decision" "Box")
arrow right from DBOX.e
circle "END"

.PE

It would be nice to have a "polygon" command in pic that works
    like:

    polygon closed shaded "green" up right 1 then \
      down right 1 then down left 1

and have it "know" where the position in the current context is so that 
it is drawn at the last object (say a line) in the proper direction, 
just like a box.


One more thing - How can I refer to my dimensions (which are being 
passed into the function) in the \v and \h escapes? For example:

  "\D'p $1 $2 $3 $4'"   <-- this doesn't work.

Thanks for looking.

Louis

smime.p7s
Description: S/MIME Cryptographic Signature