[CF-Devel] Any Line of Sight wizards out there?

[Mark Wedel]

 I'm doing work to make the viewable map a larger size (max size settable by
config.h setting).

 The little difficulty I'm running into is the line of sight code.

 If you look at the common/los.c file, near the top you will notice a whole
bunch of set_block calls - I'll copy a few below:

  set_block(5,4,4,3);
  set_block(5,4,5,3);
  set_block(5,4,6,3);
  set_block(4,3,4,2);

 This is all 'hard coded' for an 11x11 map.  Presume the player is at 5,5 (as
would be the case for an 11x11 map).

 The first line basically says that if there is something at 5,4 that blocks the
view, you can't see 4,3 (first line), 5,3 (second line), and 6,3.

 The next line then says that if something blocks view at 4,3 that you can't see
4,2.

 And so on.  This creates a whole set of relations - so if 5,4 is blocked, you
can pretty quickly figure out all the other spaces that get blocked by
traversing the structures set up.

 As evidenced in the current code, this works just fine for the 11x11 map.

 Ideally, I would like a more general solution.  I certainly don't want to have
a hard code in place for a 25x25 map (which would be hundreds of lines).

 I did a quick web search for a better LOS method, but didn't find one.  Most of
them are presuming the simpler cases (have point A and point B  - does anything
prevent them from seeing each other).

 I'm thinking of using something like that to initialize the tables in a brute
force fashion - this table is only initialized at startup, so something all that
efficient to initialize the table is not all that important.  On a 25x25 map,
there are 625 spaces.  Worst case here is also that there could still be a few
hard coded entries to fix up gaps or the like.

 But before I do that approach, just wanted to see if anyone had some more
clever solution.