root/src/map/path.c @ 19

// Copyright (c) Athena Dev Teams - Licensed under GNU GPL
// For more information, see LICENCE in the main folder

#include "../common/cbasetypes.h"
#include "../common/nullpo.h"
#include "../common/showmsg.h"
#include "../common/malloc.h"
#include "map.h"
#include "battle.h"
#include "path.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


#define MAX_HEAP 150

struct tmp_path { short x,y,dist,before,cost,flag;};
#define calc_index(x,y) (((x)+(y)*MAX_WALKPATH) & (MAX_WALKPATH*MAX_WALKPATH-1))

const char walk_choices [3][3] =
{
        {1,0,7},
        {2,-1,6},
        {3,4,5},
};

/*==========================================
 * heap push (helper function)
 *------------------------------------------*/
static void push_heap_path(int *heap,struct tmp_path *tp,int index)
{
        int i,h;

        h = heap[0];
        heap[0]++;

        for( i = (h-1)/2; h > 0 && tp[index].cost < tp[heap[i+1]].cost; i = (h-1)/2 )
                heap[h+1] = heap[i+1], h = i;

        heap[h+1] = index;
}

/*==========================================
 * heap update (helper function)
 * cost‚ªŒž‚Á‚œ‚̂ōª‚Ì•û‚ÖˆÚ“®
 *------------------------------------------*/
static void update_heap_path(int *heap,struct tmp_path *tp,int index)
{
        int i,h;

        ARR_FIND( 0, heap[0], h, heap[h+1] == index );
        if( h == heap[0] )
        {
                ShowError("update_heap_path bug\n");
                exit(EXIT_FAILURE);
        }

        for( i = (h-1)/2; h > 0 && tp[index].cost < tp[heap[i+1]].cost; i = (h-1)/2 )
                heap[h+1] = heap[i+1], h = i;

        heap[h+1] = index;
}

/*==========================================
 * heap pop (helper function)
 *------------------------------------------*/
static int pop_heap_path(int *heap,struct tmp_path *tp)
{
        int i,h,k;
        int ret,last;

        if( heap[0] <= 0 )
                return -1;
        ret = heap[1];
        last = heap[heap[0]];
        heap[0]--;

        for( h = 0, k = 2; k < heap[0]; k = k*2+2 )
        {
                if( tp[heap[k+1]].cost > tp[heap[k]].cost )
                        k--;
                heap[h+1] = heap[k+1], h = k;
        }

        if( k == heap[0] )
                heap[h+1] = heap[k], h = k-1;

        for( i = (h-1)/2; h > 0 && tp[heap[i+1]].cost > tp[last].cost; i = (h-1)/2 )
                heap[h+1] = heap[i+1], h = i;

        heap[h+1]=last;

        return ret;
}

/*==========================================
 * calculate cost for the specified position
 *------------------------------------------*/
static int calc_cost(struct tmp_path *p,int x1,int y1)
{
        int xd = abs(x1 - p->x);
        int yd = abs(y1 - p->y);
        return (xd + yd)*10 + p->dist;
}

/*==========================================
 * attach/adjust path if neccessary
 *------------------------------------------*/
static int add_path(int *heap,struct tmp_path *tp,int x,int y,int dist,int before,int cost)
{
        int i;

        i = calc_index(x,y);

        if( tp[i].x == x && tp[i].y == y )
        {
                if( tp[i].dist > dist )
                {
                        tp[i].dist = dist;
                        tp[i].before = before;
                        tp[i].cost = cost;
                        if( tp[i].flag )
                                push_heap_path(heap,tp,i);
                        else
                                update_heap_path(heap,tp,i);
                        tp[i].flag = 0;
                }
                return 0;
        }

        if( tp[i].x || tp[i].y )
                return 1;

        tp[i].x = x;
        tp[i].y = y;
        tp[i].dist = dist;
        tp[i].before = before;
        tp[i].cost = cost;
        tp[i].flag = 0;
        push_heap_path(heap,tp,i);

        return 0;
}

/*==========================================
 * Find the closest reachable cell, 'count' cells away from (x0,y0) in direction (dx,dy).
 * 
 * ‚«”ò‚΂µ‚œ‚ ‚Ƃ̍À•W‚ðŠ“Ÿ
 *------------------------------------------*/
int path_blownpos(int m,int x0,int y0,int dx,int dy,int count)
{
        struct map_data *md;

        if( !map[m].cell )
                return -1;
        md = &map[m];

        if( count>25 ){ //Cap to prevent too much processing...?
                ShowWarning("path_blownpos: count too many %d !\n",count);
                count=25;
        }
        if( dx > 1 || dx < -1 || dy > 1 || dy < -1 ){
                ShowError("path_blownpos: illegal dx=%d or dy=%d !\n",dx,dy);
                dx=(dx>0)?1:((dx<0)?-1:0);
                dy=(dy>0)?1:((dy<0)?-1:0);
        }
        
        while( count > 0 && (dx != 0 || dy != 0) )
        {
                if( !map_getcellp(md,x0+dx,y0+dy,CELL_CHKPASS) )
                {// attempt partial movement
                        int fx = ( dx != 0 && map_getcellp(md,x0+dx,y0,CELL_CHKPASS) );
                        int fy = ( dy != 0 && map_getcellp(md,x0,y0+dy,CELL_CHKPASS) );
                        if( fx && fy )
                        {
                                if(rand()&1)
                                        dx=0;
                                else
                                        dy=0;
                        }
                        if( !fx )
                                dx=0;
                        if( !fy )
                                dy=0;
                }

                x0 += dx;
                y0 += dy;
                count--;
        }

        return (x0<<16)|y0; //TODO: use 'struct point' here instead?
}

/*==========================================
 * is ranged attack from (x0,y0) to (x1,y1) possible?
 *------------------------------------------*/
bool path_search_long(struct shootpath_data *spd,int m,int x0,int y0,int x1,int y1,cell_chk cell)
{
        int dx, dy;
        int wx = 0, wy = 0;
        int weight;
        struct map_data *md;
        struct shootpath_data s_spd;

        if( spd == NULL )
                spd = &s_spd; // use dummy output variable

        if (!map[m].cell)
                return false;
        md = &map[m];

        dx = (x1 - x0);
        if (dx < 0) {
                swap(x0, x1);
                swap(y0, y1);
                dx = -dx;
        }
        dy = (y1 - y0);

        spd->rx = spd->ry = 0;
        spd->len = 1;
        spd->x[0] = x0;
        spd->y[0] = y0;

        if (map_getcellp(md,x1,y1,cell))
                return false;

        if (dx > abs(dy)) {
                weight = dx;
                spd->ry = 1;
        } else {
                weight = abs(y1 - y0);
                spd->rx = 1;
        }

        while (x0 != x1 || y0 != y1)
        {
                if (map_getcellp(md,x0,y0,cell))
                        return false;
                wx += dx;
                wy += dy;
                if (wx >= weight) {
                        wx -= weight;
                        x0++;
                }
                if (wy >= weight) {
                        wy -= weight;
                        y0++;
                } else if (wy < 0) {
                        wy += weight;
                        y0--;
                }
                if( spd->len<MAX_WALKPATH )
                {
                        spd->x[spd->len] = x0;
                        spd->y[spd->len] = y0;
                        spd->len++;
                }
        }

        return true;
}

/*==========================================
 * path search (x0,y0)->(x1,y1)
 * wpd: path info will be written here
 * flag: &1 = easy path search only
 * cell: type of obstruction to check for
 *------------------------------------------*/
bool path_search(struct walkpath_data *wpd,int m,int x0,int y0,int x1,int y1,int flag,cell_chk cell)
{
        int heap[MAX_HEAP+1];
        struct tmp_path tp[MAX_WALKPATH*MAX_WALKPATH];
        register int i,j,len,x,y,dx,dy;
        int rp,xs,ys;
        struct map_data *md;
        struct walkpath_data s_wpd;

        if( wpd == NULL )
                wpd = &s_wpd; // use dummy output variable

        if( !map[m].cell )
                return false;
        md = &map[m];

#ifdef CELL_NOSTACK
        //Do not check starting cell as that would get you stuck.
        if( x0 < 0 || x0 >= md->xs || y0 < 0 || y0 >= md->ys )
#else
        if( x0 < 0 || x0 >= md->xs || y0 < 0 || y0 >= md->ys /*|| map_getcellp(md,x0,y0,cell)*/ )
#endif
                return false;
        if( x1 < 0 || x1 >= md->xs || y1 < 0 || y1 >= md->ys || map_getcellp(md,x1,y1,cell) )
                return false;

        // calculate (sgn(x1-x0), sgn(y1-y0))
        dx = ((dx = x1-x0)) ? ((dx<0) ? -1 : 1) : 0;
        dy = ((dy = y1-y0)) ? ((dy<0) ? -1 : 1) : 0;

        // try finding direct path to target
        x = x0;
        y = y0;
        i = 0;
        while( i < ARRAYLENGTH(wpd->path) )
        {
                wpd->path[i] = walk_choices[-dy + 1][dx + 1];
                i++;

                x += dx;
                y += dy;

                if( x == x1 ) dx = 0;
                if( y == y1 ) dy = 0;

                if( dx == 0 && dy == 0 )
                        break; // success
                if( map_getcellp(md,x,y,cell) )
                        break; // obstacle = failure
        }

        if( x == x1 && y == y1 )
        { //easy path successful.
                wpd->path_len = i;
                wpd->path_pos = 0;
                return true;
        }
        
        if( flag&1 )
                return false;

        memset(tp,0,sizeof(tp));

        i=calc_index(x0,y0);
        tp[i].x=x0;
        tp[i].y=y0;
        tp[i].dist=0;
        tp[i].before=0;
        tp[i].cost=calc_cost(&tp[i],x1,y1);
        tp[i].flag=0;
        heap[0]=0;
        push_heap_path(heap,tp,calc_index(x0,y0));
        xs = md->xs-1; // ‚ ‚ç‚©‚¶‚ß‚PŒžŽZ‚µ‚Ä‚š‚­
        ys = md->ys-1;

        while(1)
        {
                int e=0,f=0,dist,cost,dc[4]={0,0,0,0};

                if(heap[0]==0)
                        return false;
                rp   = pop_heap_path(heap,tp);
                x    = tp[rp].x;
                y    = tp[rp].y;
                dist = tp[rp].dist + 10;
                cost = tp[rp].cost;

                if(x==x1 && y==y1)
                        break;

                // dc[0] : y++ ‚ÌŽž‚̃RƒXƒg‘•ª
                // dc[1] : x-- ‚ÌŽž‚̃RƒXƒg‘•ª
                // dc[2] : y-- ‚ÌŽž‚̃RƒXƒg‘•ª
                // dc[3] : x++ ‚ÌŽž‚̃RƒXƒg‘•ª

                if(y < ys && !map_getcellp(md,x  ,y+1,cell)) {
                        f |= 1; dc[0] = (y >= y1 ? 20 : 0);
                        e+=add_path(heap,tp,x  ,y+1,dist,rp,cost+dc[0]); // (x,   y+1)
                }
                if(x > 0  && !map_getcellp(md,x-1,y  ,cell)) {
                        f |= 2; dc[1] = (x <= x1 ? 20 : 0);
                        e+=add_path(heap,tp,x-1,y  ,dist,rp,cost+dc[1]); // (x-1, y  )
                }
                if(y > 0  && !map_getcellp(md,x  ,y-1,cell)) {
                        f |= 4; dc[2] = (y <= y1 ? 20 : 0);
                        e+=add_path(heap,tp,x  ,y-1,dist,rp,cost+dc[2]); // (x  , y-1)
                }
                if(x < xs && !map_getcellp(md,x+1,y  ,cell)) {
                        f |= 8; dc[3] = (x >= x1 ? 20 : 0);
                        e+=add_path(heap,tp,x+1,y  ,dist,rp,cost+dc[3]); // (x+1, y  )
                }
                if( (f & (2+1)) == (2+1) && !map_getcellp(md,x-1,y+1,cell))
                        e+=add_path(heap,tp,x-1,y+1,dist+4,rp,cost+dc[1]+dc[0]-6);              // (x-1, y+1)
                if( (f & (2+4)) == (2+4) && !map_getcellp(md,x-1,y-1,cell))
                        e+=add_path(heap,tp,x-1,y-1,dist+4,rp,cost+dc[1]+dc[2]-6);              // (x-1, y-1)
                if( (f & (8+4)) == (8+4) && !map_getcellp(md,x+1,y-1,cell))
                        e+=add_path(heap,tp,x+1,y-1,dist+4,rp,cost+dc[3]+dc[2]-6);              // (x+1, y-1)
                if( (f & (8+1)) == (8+1) && !map_getcellp(md,x+1,y+1,cell))
                        e+=add_path(heap,tp,x+1,y+1,dist+4,rp,cost+dc[3]+dc[0]-6);              // (x+1, y+1)
                tp[rp].flag=1;
                if(e || heap[0]>=MAX_HEAP-5)
                        return false;
        }

        if( !(x==x1 && y==y1) ) // will never happen...
                return false;
        
        for(len=0,i=rp;len<100 && i!=calc_index(x0,y0);i=tp[i].before,len++);
        if(len==100 || len>=sizeof(wpd->path))
                return false;

        wpd->path_len = len;
        wpd->path_pos = 0;
        for(i=rp,j=len-1;j>=0;i=tp[i].before,j--) {
                int dx  = tp[i].x - tp[tp[i].before].x;
                int dy  = tp[i].y - tp[tp[i].before].y;
                int dir;
                if( dx == 0 ) {
                        dir = (dy > 0 ? 0 : 4);
                } else if( dx > 0 ) {
                        dir = (dy == 0 ? 6 : (dy < 0 ? 5 : 7) );
                } else {
                        dir = (dy == 0 ? 2 : (dy > 0 ? 1 : 3) );
                }
                wpd->path[j] = dir;
        }

        return true;
}


//Distance functions, taken from http://www.flipcode.com/articles/article_fastdistance.shtml
int check_distance(int dx, int dy, int distance)
{
#ifdef CIRCULAR_AREA
        //In this case, we just do a square comparison. Add 1 tile grace for diagonal range checks.
        return (dx*dx + dy*dy <= distance*distance + (dx&&dy?1:0));
#else
        if (dx < 0) dx = -dx;
        if (dy < 0) dy = -dy;
        return ((dx<dy?dy:dx) <= distance);
#endif
}

unsigned int distance(int dx, int dy)
{
#ifdef CIRCULAR_AREA
        unsigned int min, max;

        if ( dx < 0 ) dx = -dx;
        if ( dy < 0 ) dy = -dy;
        //There appears to be something wrong with the aproximation below when either dx/dy is 0! [Skotlex]
        if ( dx == 0 ) return dy;
        if ( dy == 0 ) return dx;
        
        if ( dx < dy )
        {
                min = dx;
                max = dy;
        } else {
                min = dy;
                max = dx;
        }
   // coefficients equivalent to ( 123/128 * max ) and ( 51/128 * min )
        return ((( max << 8 ) + ( max << 3 ) - ( max << 4 ) - ( max << 1 ) +
                ( min << 7 ) - ( min << 5 ) + ( min << 3 ) - ( min << 1 )) >> 8 );
#else
        if (dx < 0) dx = -dx;
        if (dy < 0) dy = -dy;
        return (dx<dy?dy:dx);
#endif
}