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

[Ted Harding]

On 09-Mar-09 03:44:33, Louis Guillaume wrote:
> Hi,
> I'm making a flowchart with pic and I want to fill a "decision"
> diamond, which is drawn like this...
> 
> define decision {
>    DECA: box invis wid $1 ht $2 $3
>    line from DECA.w to DECA.n then to DECA.e then to DECA.s then to
> DECA.w
> }
> 
> ... is there a better way to draw the diamond? Or perhaps close the
> path made by the four lines so that it can be filled?
> 
> Louis

Have a look at the following and see if you can adapt to do
what you want:

.PS
box wid 2 ht 2 at (0,0)
"\v'-0.5n'\D'p 1i -1i 1i 1i -1i 1i -1i -1i'" at (-1,0) 
box wid 2 ht 2 at (0,-3)
"\v'-0.5n'\D'P 1i -1i 1i 1i -1i 1i -1i -1i'" at (-1,-3)
.PE


It is based on the fact that, when you tell 'pic' to draw a unit
"box", it outputs

\h'0.750i'\v'0.500i'\D'p0.000i -0.500i -0.750i 0.000i 0.000i 0.500i'

In other words it uses troff's \D'p ... ' "polygon" drawing
command. With \D'p ... ' you get the outline of the polygon.
If you use \D'P ... ' instead, you get a filled polygon (with
the current fill-value).

The "\v'-0.5n'" was put in empirically!

Hoping this helps, and please repot back!
Ted.

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Date: 09-Mar-09                                       Time: 20:43:08
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