Sender: nate AT cartsys DOT com
Message-ID: <36856D22.9F3965BF@cartsys.com>
Date: Sat, 26 Dec 1998 15:11:30 -0800
From: Nate Eldredge <nate AT cartsys DOT com>
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To: djgpp AT delorie DOT com
Subject: Re: StarMaps
References: <3 DOT 0 DOT 6 DOT 32 DOT 19981225124707 DOT 007aaec0 AT tenforward DOT com>
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Reply-To: djgpp AT delorie DOT com

Mad Cow wrote:
> 
> humm..I'm a novice djgpp'er, and need some help on somethin'
> 
> i want to make a StarMap, uh, like so--
> 
>      1 2 3 4 5 6 7 8 9 0
>    A * * * * * * * * * *
>    B * * * * * * * * * *
>    C * * # * * * * * * *
>    D * * * * * * * * * *
>    E * * * * * * * * * *
>    F * * * * * * * * * *
>    G * * * * * * * * * *
>    H * * * * * * # * * *
>    I * * * * * * * * * *
>    J * * * * * * * * * *
> 
>         This is a game i want to make, i want to have it so that ppl can
> move a ship from
>         say  C3 to  H7  but, how do i make a thing to calculate distance, and
> maybe even a path?
>         say the distance would be  5, and the path would be C3-D4-E5-F6-G7-H7, so,
> please help
>         on this one..all help is deeply apreciated..

The distance between two points in a plane is `sqrt(x^2+y^2)', so

#define SQ(x) ((x) * (x))

double distance(double x1, double y1, double x2, double y2)
{
  return sqrt(SQ(x1-x2) + SQ(y1-y2));
}

and round to int as appropriate.

To determine the path, you want a line drawing algorithm.  Breshenham's
algorithm (sp?) is the best known; search for it.  You could also look
at the sources of a graphics library like Allegro and see how it's
done.  You just have grid squares instead of pixels.
-- 

Nate Eldredge
nate AT cartsys DOT com