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#include "cp_types.h"
#include "cp_proto.h"
/* Return an edge path from start edge as described in datastr,
using either (flag=0) multiple-choice (default: for multi-sheeted
surfaces) or (flag=1) flower-increment next vertices.
datastr describes path in terms of 'turns' in combinatoric direction.
First in list <v..> must be a neighbor of v1, then succession of
increments. E.g., "path_c 23 57 2 4 0 3 3" will start with edge
<23,57>, then <57,x>, where in the flower for 57, <57,x> is "2" edges
counterclockwise from <57,23>, then "4" edges around x, then "0" (back
up), etc. In a hex packing, "path_c 23 57 3 3 3 ..." defines a
combinatorial straight path. */
struct Vertlist *path_construct(struct p_data *p,int flag,char *datastr)
{
int count=2,v1,v2,v,m,cur_vert,inc,dir;
char *nextpoint,next[256];
struct Vertlist *trace,*clobber,*final;
stripsp(datastr);
nextpoint=datastr;
if (*datastr=='-')
{
grab_next(&nextpoint,next);
if (next[1]=='i') flag=1;
}
if (!(v1=grab_one_vert(p,&nextpoint))) return NULL;
final=trace=(struct Vertlist *)
calloc((size_t)1,sizeof(struct Vertlist));
final->v=cur_vert=v1;
clobber=trace;
trace=trace->next=(struct Vertlist *)
calloc((size_t)1,sizeof(struct Vertlist));
if (flag==0) /* multiple-choice; exit upon hitting illegal */
{
while ((v=grab_one_vert(p,&nextpoint)))
if (nghb(p,cur_vert,v)>=0)
{
trace->v=v;
clobber=trace;
trace=trace->next=(struct Vertlist *)
calloc((size_t)1,sizeof(struct Vertlist));
cur_vert=v;
count++;
}
}
else if (flag==1 && (v2=grab_one_vert(p,&nextpoint))
&& (dir=nghb(p,v2,v1))>=0) /* incremental; exit upon illegal. */
{
trace->v=cur_vert=v2;
clobber=trace;
trace=trace->next=(struct Vertlist *)
calloc((size_t)1,sizeof(struct Vertlist));
while (grab_next(&nextpoint,next) && sscanf(next,"%d",&inc)
&& inc>=0 && (!p->packK_ptr[cur_vert].bdry_flag
|| (inc+dir)<=p->packK_ptr[cur_vert].num))
{
m=(inc+dir)%(p->packK_ptr[cur_vert].num);
trace->v=p->packK_ptr[cur_vert].flower[m];
clobber=trace;
dir=nghb(p,trace->v,cur_vert);
cur_vert=trace->v;
trace=trace->next=(struct Vertlist *)
calloc((size_t)1,sizeof(struct Vertlist));
count++;
}
}
else count=0;
clobber->next=NULL;
free(trace);
return final;
} /* path_construct */
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