377 lines
8.6 KiB
C
377 lines
8.6 KiB
C
/*
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* Empire - A multi-player, client/server Internet based war game.
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* Copyright (C) 1986-2010, Dave Pare, Jeff Bailey, Thomas Ruschak,
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* Ken Stevens, Steve McClure
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* ---
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*
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* See files README, COPYING and CREDITS in the root of the source
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* tree for related information and legal notices. It is expected
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* that future projects/authors will amend these files as needed.
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*
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* ---
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*
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* path.c: Empire/A* Interface code.
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* Define AS_STATS for A* statistics.
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*
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* Known contributors to this file:
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* Phil Lapsley, 1991
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* Dave Pare, 1991
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* Thomas Ruschak, 1993
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* Steve McClure, 1997
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*/
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#include <config.h>
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#include <stdio.h>
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#include "../as/as.h"
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#include "file.h"
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#include "misc.h"
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#include "optlist.h"
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#include "path.h"
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#include "prototypes.h"
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#include "sect.h"
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#include "xy.h"
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#define BP_ASHASHSIZE 128 /* A* queue hash table size */
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#define BP_NEIGHBORS 6 /* max number of neighbors */
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struct bestp {
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int sctcache_hits;
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int sctcache_misses;
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int bp_mobtype;
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struct as_data *adp;
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};
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static int bp_path(struct as_path *pp, char *buf);
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static int bp_neighbors(struct as_coord c, struct as_coord *cp, void *);
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static double bp_lbcost(struct as_coord from, struct as_coord to, void *);
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static double bp_realcost(struct as_coord from, struct as_coord to, void *);
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static double bp_seccost(struct as_coord from, struct as_coord to, void *);
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static int bp_coord_hash(struct as_coord c);
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/* We use this for caching neighbors. It never changes except
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* at reboot time (maybe) so we never need to free it */
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static struct sctstr **neighsects;
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static struct bestp *
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bp_init(void)
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{
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struct bestp *bp;
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bp = malloc(sizeof(*bp));
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memset(bp, 0, sizeof(*bp));
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bp->adp = as_init(BP_NEIGHBORS, BP_ASHASHSIZE, bp_coord_hash,
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bp_neighbors, bp_lbcost, bp_realcost,
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bp_seccost, bp);
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if (bp->adp == NULL)
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return NULL;
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if (neighsects == NULL)
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neighsects = calloc(WORLD_SZ() * 6, sizeof(struct sctstr *));
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return bp;
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}
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/*
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* Find the best path from sector to to sector, and put the Empire movement
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* string in path. Return 0 on success, -1 on error.
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*/
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static int
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best_path(struct sctstr *from, struct sctstr *to, char *path, int mob_type)
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{
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static struct bestp *mybestpath;
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struct as_data *adp;
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struct as_path *ap;
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if (!mybestpath)
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mybestpath = bp_init();
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adp = mybestpath->adp;
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ap = as_find_cachepath(from->sct_x, from->sct_y, to->sct_x, to->sct_y);
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if (ap == NULL) {
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adp->from.x = from->sct_x;
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adp->from.y = from->sct_y;
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adp->to.x = to->sct_x;
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adp->to.y = to->sct_y;
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mybestpath->bp_mobtype = mob_type;
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if (as_search(adp) < 0)
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return -1;
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ap = adp->path;
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}
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if (bp_path(ap, path) < 0)
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return -1;
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#ifdef AS_STATS
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as_stats(adp, stderr);
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#endif /* AS_STATS */
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#ifdef BP_STATS
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fprintf(stderr, "best path %s\n", path);
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fprintf(stderr, "cache hits/misses: %d/%d\n",
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bp->sctcache_hits, bp->sctcache_misses);
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#endif /* BP_STATS */
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return 0;
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}
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/*
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* Translate an A* path into an empire movement string. Return 0 on
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* success, -1 on failure.
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*/
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static int
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bp_path(struct as_path *pp, char *buf)
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{
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struct as_path *np;
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char *cp = buf;
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int dx, dy;
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int n;
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np = pp->next;
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while (np) {
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dx = np->c.x - pp->c.x;
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/* deal with wraparound from non-neg coords */
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if (dx < -2)
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dx += WORLD_X;
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else if (dx > 2)
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dx -= WORLD_X;
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dy = np->c.y - pp->c.y;
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if (dy < -1)
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dy += WORLD_Y;
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else if (dy > 1)
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dy -= WORLD_Y;
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for (n = 1; n <= 6; n++)
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if (dx == diroff[n][0] && dy == diroff[n][1])
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break;
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if (n > 6)
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return -1;
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*cp++ = dirch[n];
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pp = np;
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np = np->next;
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}
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*cp = '\0';
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return 0;
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}
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/*
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* Find coords neighboring this sector; return number of such
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* coords, and coordinartes themselves in an array pointed
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* to by *cpp.
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* XXX need to check ownership, sector types, etc.
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*/
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static int
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bp_neighbors(struct as_coord c, struct as_coord *cp, void *pp)
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{
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struct sctstr *sectp = (void *)empfile[EF_SECTOR].cache;
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struct bestp *bp = pp;
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coord x, y;
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coord nx, ny;
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int n = 0, i;
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struct sctstr *sp, *from, **ssp;
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/* Six pointers, just in case our cache isn't there */
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struct sctstr *tsp[] = { NULL, NULL, NULL, NULL, NULL, NULL };
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int sx, sy, offset;
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x = c.x;
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y = c.y;
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sx = XNORM(x);
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sy = YNORM(y);
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offset = XYOFFSET(sx, sy);
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from = §p[offset];
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if (neighsects == NULL)
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ssp = (struct sctstr **)&tsp[0];
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else
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ssp = (struct sctstr **)&neighsects[offset * 6];
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for (i = 1; i <= 6; i++, ssp++) {
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if (*ssp == NULL) {
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/* We haven't cached this neighbor yet */
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nx = x + diroff[i][0];
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ny = y + diroff[i][1];
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sx = XNORM(nx);
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sy = YNORM(ny);
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offset = XYOFFSET(sx, sy);
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sp = §p[offset];
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*ssp = sp;
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} else {
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sp = *ssp;
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sx = XNORM(sp->sct_x);
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sy = YNORM(sp->sct_y);
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}
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/* No need to calculate cost each time, just make sure we can
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move through it. We calculate it later. */
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if (dchr[sp->sct_type].d_mob0 < 0)
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continue;
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if (bp->bp_mobtype == MOB_RAIL && !SCT_HAS_RAIL(sp))
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continue;
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if (sp->sct_own != from->sct_own)
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continue;
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cp[n].x = sx;
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cp[n].y = sy;
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n++;
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}
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return n;
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}
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/*
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* Compute a lower-bound on the cost from "from" to "to".
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*/
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/*ARGSUSED*/
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static double
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bp_lbcost(struct as_coord from, struct as_coord to, void *pp)
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{
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struct sctstr *sectp = (void *)empfile[EF_SECTOR].cache;
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struct bestp *bp = pp;
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int x, y, sx, sy, offset;
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x = to.x;
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y = to.y;
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sx = XNORM(x);
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sy = YNORM(y);
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offset = XYOFFSET(sx, sy);
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return sector_mcost(§p[offset], bp->bp_mobtype);
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}
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/*
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* Compute the real cost to move from "from" to "to".
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*/
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static double
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bp_realcost(struct as_coord from, struct as_coord to, void *pp)
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{
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return bp_lbcost(from, to, pp);
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}
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/*
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* Tie breaker secondary metric (only used when lower bound costs
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* are equal).
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*/
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/*ARGSUSED*/
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static double
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bp_seccost(struct as_coord from, struct as_coord to, void *pp)
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{
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return mapdist((coord)from.x, (coord)from.y,
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(coord)to.x, (coord)to.y);
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}
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/*
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* Hash a coordinate into an integer.
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*/
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static int
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bp_coord_hash(struct as_coord c)
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{
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return ((abs(c.x) + 1) << 3) ^ abs(c.y);
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}
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void
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bp_enable_cachepath(void)
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{
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as_enable_cachepath();
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}
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void
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bp_disable_cachepath(void)
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{
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as_disable_cachepath();
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}
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void
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bp_clear_cachepath(void)
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{
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as_clear_cachepath();
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}
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double
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pathcost(struct sctstr *start, char *path, int mob_type)
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{
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struct sctstr *sectp = (void *)empfile[EF_SECTOR].cache;
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unsigned i;
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int o;
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int cx, cy;
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double cost = 0.0;
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struct sctstr *sp;
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int sx, sy, offset;
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cx = start->sct_x;
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cy = start->sct_y;
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while (*path) {
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if (*path == 'h') {
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path++;
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continue;
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}
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i = *path - 'a';
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if (CANT_HAPPEN(i >= sizeof(dirindex) / sizeof(*dirindex)))
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break;
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o = dirindex[i];
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if (CANT_HAPPEN(o < 0))
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break;
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cx += diroff[o][0];
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cy += diroff[o][1];
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sx = XNORM(cx);
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sy = YNORM(cy);
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offset = XYOFFSET(sx, sy);
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sp = §p[offset];
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cost += sector_mcost(sp, mob_type);
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path++;
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}
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return cost;
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}
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char *
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BestDistPath(char *path,
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struct sctstr *from,
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struct sctstr *to, double *cost)
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{
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return BestLandPath(path, from, to, cost, MOB_MOVE);
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}
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char *
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BestLandPath(char *path,
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struct sctstr *from,
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struct sctstr *to, double *cost, int mob_type)
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{
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int length;
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*path = 0;
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*cost = 0.0;
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if (best_path(from, to, path, mob_type) < 0)
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return NULL;
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*cost = pathcost(from, path, mob_type);
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length = strlen(path);
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path[length] = 'h';
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path[length + 1] = '\0';
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return path;
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}
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char *
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BestShipPath(char *path, int fx, int fy, int tx, int ty, int owner)
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{
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char *map;
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map = ef_ptr(EF_BMAP, owner);
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if (!map)
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return NULL;
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return bestownedpath(path, map, fx, fy, tx, ty, owner);
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}
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char *
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BestAirPath(char *path, int fx, int fy, int tx, int ty)
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{
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return bestownedpath(path, NULL, fx, fy, tx, ty, -1);
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}
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