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MatPlus.Net Forum Internet and Computing Antigrid in Popeye?

### Antigrid in Popeye?

For theoretical analysis, I'd like to insert
an antigrid line between two neighboring squares
A and B (i.e. nothing can move between A and B).
Should be possible by "condition grid irregular"
and then declaring everything else than A|B
as grid line. Say, d5-e5, how would it look?

You have probably received an answer long ago...
But I assume you wanted this: GridChess Irregular gridline Ve51

THX and no, I haven't ;-)
(Ve51? Vertical, e5, 1 to the left?)

yes

THX again. But that is a grid line (not antigrid) and then
I have to declare all 8*6*2-1 *except* the one I want as "grid", right,
i.e. Vb81 Vc81... to kingdom come?
(As usual I will write a Python program to generate that input :-)

Should a piece on b5 be able to move to g5, so through the antigridline?

If yes, then it's probably easiest to define 7 horizontal and 8 vertical gridlines.
If no, then the grid without the d5/e5 line won't work

More question:
- Can, with an antigrid line between d5 and e5, a knight move from d5 to f6 (the straight line between the centers of d5 and f6 crosses the antigrid line between d5 and e5)?
- Can a rose move from b5 to f5 with an antigridline between d5 and e5?

grid irregular gridline Va18 Vb18 Vc18 Vd18 Vf18 Vg18 Vh18 Ha28 Ha38 Ha48 Ha58 Ha68 Ha78 Ha88 Ve14 Ve63
will define a grid everywhere except between d5 and e5

Aha! Quite needs getting used to, the notation.

@Joost: Indeed, an antigrid line shall block ALL traffic
through that boundary (and that is the problem -
with grid chess it doesn't work!). Good that you
pointed it out.

(9) Posted by Joost de Heer [Monday, Feb 12, 2024 08:13]

QUOTE

rid irregular gridline Va18 Vb18 Vc18 Vd18 Vf18 Vg18 Vh18 Ha28 Ha38 Ha48 Ha58 Ha68 Ha78 Ha88 Ve14 Ve63
will define a grid everywhere except between d5 and e5

Another way which may be easier to remember:
grid irregular a1 a2 a3 .... d3 d4 d6 d7 .. e3 e4 e6 e7 ... h7 h8
This will define a grid with all 1-cell square groups, and the missing squares (d5 and e5) are grouped together as the final group.

And FYI: Winchloe also doesn't know Antigrid, as far as I can see (searched for 'gril' in the conditions table)

And to reply to my earlier questions: I found this in the Popeye readme:
QUOTE

(N.B. In the context of grid chess, moves go as straight lines from square centre to square centre; pieces that do not move in straight lines may not behave as expected; moves are permitted which merely touch the end of a gridline (e.g with gridline Ve11 and wKd1, the move Kd1-e2 is legal).

So if antigrid was implemented, ROb5xf5 would probably be illegal with an antigridline between d5 and e5.