RE: [Groff] Cascading boxes with pic?

[Ted Harding]

On 17-Apr-10 19:09:49, Jeronimo Pellegrini wrote:
> Hello,
> 
> Ijust started learning to use pic but there's something I didn't
> find in the tutorials I've found (and it looks like the section
> of the Groff manual on pic is empty).
> 
> I'd like to draw a number of boxes in "cascading" style, like this:
> 
> .PS
> A:box wid 0.7i ht 1i
> B:box wid 0.7i ht 1i at (A.e.x-0.1i, A.e.y-0.1i)
> C:box wid 0.7i ht 1i at (B.e.x-0.1i, B.e.y-0.1i)
> .PE
> 
> But this actually draws all of them completely -- I'd like the
> topmost to actually hide part of the box below it, and so on, so
> the picture would look as paper sheets diagonally aligned on a desk.
> 
> Is there a simple way to do that? Can I, for example, fill the boxes
> with white so that'd cover the lines behind it?
> 
> Thanks,
> Jeronimo

Yes, you can -- use 'shaded "white"' as in:

.PS
A:box wid 0.7i ht 1i
B:box wid 0.7i ht 1i at (A.e.x-0.1i, A.e.y-0.1i) shaded "white"
C:box wid 0.7i ht 1i at (B.e.x-0.1i, B.e.y-0.1i) shaded "white"
.PE

Only: this will make C appear on top of B which will appear
on top of A (they are drawn in the order written, so the shading
of B will overlay part of A, and the shading of C will overlay
part of B.

So, to answer your description (if I have understood correctly,
i.e. A is the top one and should overlay B which should overlay C)
you would need to change the signs of the relative positions,
and the reference point to "w" instead of "e":

.PS
A:box wid 0.7i ht 1i
B:box wid 0.7i ht 1i at (A.w.x+0.1i, A.w.y+0.1i) shaded "white"
C:box wid 0.7i ht 1i at (B.w.x+0.1i, B.w.y+0.1i) shaded "white"
.PE

Note that you should not use 'coloured "white"', since this
will make the entire box (including outline) white, and it
will disappear:

.PS
A:box wid 0.7i ht 1i
B:box wid 0.7i ht 1i at (A.w.x+0.1i, A.w.y+0.1i)  coloured "white"
C:box wid 0.7i ht 1i at (B.w.x+0.1i, B.w.y+0.1i) shaded "white"
.PE

Since "white" is at one end of the range of greys given by 'fill x',
where x is a number between 0 (white) and 1 (black), you can also
use this (and its simpler for your case):

.PS
A:box wid 0.7i ht 1i
B:box wid 0.7i ht 1i at (A.w.x+0.1i, A.w.y+0.1i) fill 0
C:box wid 0.7i ht 1i at (B.w.x+0.1i, B.w.y+0.1i) fill 0
.PE

The use of 'shaded', however, gives you the option of useing other
colours, not just greys.

Hoping this helps,
Ted.

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Date: 17-Apr-10                                       Time: 22:04:15
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