/*
 *  Empire - A multi-player, client/server Internet based war game.
 *  Copyright (C) 1986-2015, Dave Pare, Jeff Bailey, Thomas Ruschak,
 *                Ken Stevens, Steve McClure, Markus Armbruster
 *
 *  Empire 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 3 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, see <http://www.gnu.org/licenses/>.
 *
 *  ---
 *
 *  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:
 *
 */

#include <config.h>

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

static 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;
}

static 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;

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