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

[Michael Toennies]

These are 2 of the best resources you can find...

     
     http://www-cs-students.stanford.edu/~amitp/gameprog.html
     
     

and

     
     http://www.gameai.com/ai.html
     
     

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       I'm doing work to make the viewable map a larger size (max size
     
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      settable by
     
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      config.h setting).
     
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       The little difficulty I'm running into is the line of sight code.
     
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       If you look at the common/los.c file, near the top you will
     
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      notice a whole
     
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      bunch of set_block calls - I'll copy a few below:
     
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        set_block(5,4,4,3);
     
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        set_block(5,4,5,3);
     
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        set_block(5,4,6,3);
     
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        set_block(4,3,4,2);
     
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       This is all 'hard coded' for an 11x11 map.  Presume the player
     
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      is at 5,5 (as
     
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      would be the case for an 11x11 map).
     
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       The first line basically says that if there is something at 5,4
     
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      that blocks the
     
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      view, you can't see 4,3 (first line), 5,3 (second line), and 6,3.
     
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       The next line then says that if something blocks view at 4,3
     
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      that you can't see
     
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      4,2.
     
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       And so on.  This creates a whole set of relations - so if 5,4 is
     
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      blocked, you
     
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      can pretty quickly figure out all the other spaces that get blocked by
     
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      traversing the structures set up.
     
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       As evidenced in the current code, this works just fine for the 11x11 map.
     
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       Ideally, I would like a more general solution.  I certainly
     
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      don't want to have
     
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      a hard code in place for a 25x25 map (which would be hundreds of lines).
     
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       I did a quick web search for a better LOS method, but didn't
     
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      find one.  Most of
     
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      them are presuming the simpler cases (have point A and point B  -
     
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      does anything
     
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      prevent them from seeing each other).
     
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       I'm thinking of using something like that to initialize the
     
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      tables in a brute
     
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      force fashion - this table is only initialized at startup, so
     
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      something all that
     
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      efficient to initialize the table is not all that important.  On
     
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      a 25x25 map,
     
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      there are 625 spaces.  Worst case here is also that there could
     
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      still be a few
     
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      hard coded entries to fix up gaps or the like.
     
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       But before I do that approach, just wanted to see if anyone had some more
     
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      clever solution.
     
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