Datum
interpt_pp(PG_FUNCTION_ARGS)
{
PATH *p1 = PG_GETARG_PATH_P(0);
PATH *p2 = PG_GETARG_PATH_P(1);
int i,
j;
LSEG seg1,
seg2;
bool found; /* We've found the intersection */
found = false; /* Haven't found it yet */
for (i = 0; i < p1->npts - 1 && !found; i++)
{
regress_lseg_construct(&seg1, &p1->p[i], &p1->p[i + 1]);
for (j = 0; j < p2->npts - 1 && !found; j++)
{
regress_lseg_construct(&seg2, &p2->p[j], &p2->p[j + 1]);
if (DatumGetBool(DirectFunctionCall2(lseg_intersect,
LsegPGetDatum(&seg1),
LsegPGetDatum(&seg2))))
found = true;
}
}
if (!found)
PG_RETURN_NULL();
/*
* Note: DirectFunctionCall2 will kick out an error if lseg_interpt()
* returns NULL, but that should be impossible since we know the two
* segments intersect.
*/
PG_RETURN_DATUM(DirectFunctionCall2(lseg_interpt,
LsegPGetDatum(&seg1),
LsegPGetDatum(&seg2)));
}
Datum
regress_path_dist(PG_FUNCTION_ARGS)
{
PATH *p1 = PG_GETARG_PATH_P(0);
PATH *p2 = PG_GETARG_PATH_P(1);
bool have_min = false;
float8 min = 0.0; /* initialize to keep compiler quiet */
float8 tmp;
int i,
j;
LSEG seg1,
seg2;
for (i = 0; i < p1->npts - 1; i++)
{
for (j = 0; j < p2->npts - 1; j++)
{
regress_lseg_construct(&seg1, &p1->p[i], &p1->p[i + 1]);
regress_lseg_construct(&seg2, &p2->p[j], &p2->p[j + 1]);
tmp = DatumGetFloat8(DirectFunctionCall2(lseg_distance,
LsegPGetDatum(&seg1),
LsegPGetDatum(&seg2)));
if (!have_min || tmp < min)
{
min = tmp;
have_min = true;
}
}
}
if (!have_min)
PG_RETURN_NULL();
PG_RETURN_FLOAT8(min);
}
Datum
regress_dist_ptpath(PG_FUNCTION_ARGS)
{
Point *pt = PG_GETARG_POINT_P(0);
PATH *path = PG_GETARG_PATH_P(1);
float8 result = 0.0; /* keep compiler quiet */
float8 tmp;
int i;
LSEG lseg;
switch (path->npts)
{
case 0:
PG_RETURN_NULL();
case 1:
result = point_dt(pt, &path->p[0]);
break;
default:
/*
* the distance from a point to a path is the smallest distance
* from the point to any of its constituent segments.
*/
Assert(path->npts > 1);
for (i = 0; i < path->npts - 1; ++i)
{
regress_lseg_construct(&lseg, &path->p[i], &path->p[i + 1]);
tmp = DatumGetFloat8(DirectFunctionCall2(dist_ps,
PointPGetDatum(pt),
LsegPGetDatum(&lseg)));
if (i == 0 || tmp < result)
result = tmp;
}
break;
}
PG_RETURN_FLOAT8(result);
}