/*
 *  Empire - A multi-player, client/server Internet based war game.
 *  Copyright (C) 1986-2008, Dave Pare, Jeff Bailey, Thomas Ruschak,
 *                           Ken Stevens, Steve McClure
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  ---
 *
 *  See files README, COPYING and CREDITS in the root of the source
 *  tree for related information and legal notices.  It is expected
 *  that future projects/authors will amend these files as needed.
 *
 *  ---
 *
 *  mapdist.c: Return the distance between two sectors
 * 
 *  Known contributors to this file:
 *     
 */

/*
 * mapdist returns (integer) distance between two sectors.
 */

#include <config.h>

#include "misc.h"
#include "optlist.h"
#include "prototypes.h"

int
deltax(int x1, int x2)
{
    int dx;

    dx = abs(x1 - x2);
    dx = dx % WORLD_X;
    if (dx > WORLD_X / 2)
	dx = WORLD_X - dx;
    return dx;
}

int
deltay(int y1, int y2)
{
    int dy;

    dy = abs(y1 - y2);
    dy = dy % WORLD_Y;
    if (dy > WORLD_Y / 2)
	dy = WORLD_Y - dy;
    return dy;
}

int
mapdist(int x1, int y1, int x2, int y2)
{
    int dx, dy;

    x1 = x1 % WORLD_X;
    y1 = y1 % WORLD_Y;
    x2 = x2 % WORLD_X;
    y2 = y2 % WORLD_Y;
    dx = deltax(x1, x2);
    dy = deltay(y1, y2);
    if (dx > dy)
	return (dx - dy) / 2 + dy;
    return dy;
}