/**
* Re-write the measure ordinate (or add one, if it isn't already there) interpolating
* the measure between the supplied start and end values.
*/
LWMLINE*
lwmline_measured_from_lwmline(const LWMLINE *lwmline, double m_start, double m_end)
{
int i = 0;
int hasm = 0, hasz = 0;
double length = 0.0, length_so_far = 0.0;
double m_range = m_end - m_start;
LWGEOM **geoms = NULL;
if ( lwmline->type != MULTILINETYPE )
{
lwerror("lwmline_measured_from_lmwline: only multiline types supported");
return NULL;
}
hasz = FLAGS_GET_Z(lwmline->flags);
hasm = 1;
/* Calculate the total length of the mline */
for ( i = 0; i < lwmline->ngeoms; i++ )
{
LWLINE *lwline = (LWLINE*)lwmline->geoms[i];
if ( lwline->points && lwline->points->npoints > 1 )
{
length += ptarray_length_2d(lwline->points);
}
}
if ( lwgeom_is_empty((LWGEOM*)lwmline) )
{
return (LWMLINE*)lwcollection_construct_empty(MULTILINETYPE, lwmline->srid, hasz, hasm);
}
geoms = lwalloc(sizeof(LWGEOM*) * lwmline->ngeoms);
for ( i = 0; i < lwmline->ngeoms; i++ )
{
double sub_m_start, sub_m_end;
double sub_length = 0.0;
LWLINE *lwline = (LWLINE*)lwmline->geoms[i];
if ( lwline->points && lwline->points->npoints > 1 )
{
sub_length = ptarray_length_2d(lwline->points);
}
sub_m_start = (m_start + m_range * length_so_far / length);
sub_m_end = (m_start + m_range * (length_so_far + sub_length) / length);
geoms[i] = (LWGEOM*)lwline_measured_from_lwline(lwline, sub_m_start, sub_m_end);
length_so_far += sub_length;
}
return (LWMLINE*)lwcollection_construct(lwmline->type, lwmline->srid, NULL, lwmline->ngeoms, geoms);
}
double
lwtriangle_perimeter_2d(const LWTRIANGLE *triangle)
{
if( triangle->points )
return ptarray_length_2d(triangle->points);
else
return 0.0;
}
/**
* Compute the sum of polygon rings length (forcing 2d computation).
* Could use a more numerically stable calculator...
*/
double
lwpoly_perimeter_2d(const LWPOLY *poly)
{
double result=0.0;
int i;
LWDEBUGF(2, "in lwgeom_polygon_perimeter (%d rings)", poly->nrings);
for (i=0; i<poly->nrings; i++)
result += ptarray_length_2d(poly->rings[i]);
return result;
}
/**
* Find the 3d/2d length of the given #POINTARRAY
* (depending on its dimensionality)
*/
double
ptarray_length(const POINTARRAY *pts)
{
double dist = 0.0;
int i;
POINT3DZ frm;
POINT3DZ to;
if ( pts->npoints < 2 ) return 0.0;
/* compute 2d length if 3d is not available */
if ( ! FLAGS_GET_Z(pts->flags) ) return ptarray_length_2d(pts);
for (i=0; i<pts->npoints-1; i++)
{
getPoint3dz_p(pts, i, &frm);
getPoint3dz_p(pts, i+1, &to);
dist += sqrt( ( (frm.x - to.x)*(frm.x - to.x) ) +
((frm.y - to.y)*(frm.y - to.y) ) +
((frm.z - to.z)*(frm.z - to.z) ) );
}
return dist;
}
int
lwline_split_by_point_to(const LWLINE* lwline_in, const LWPOINT* blade_in,
LWMLINE* v)
{
double loc, dist;
POINT4D pt, pt_projected;
POINTARRAY* pa1;
POINTARRAY* pa2;
double vstol; /* vertex snap tolerance */
/* Possible outcomes:
*
* 1. The point is not on the line or on the boundary
* -> Leave collection untouched, return 0
* 2. The point is on the boundary
* -> Push 1 element on the collection:
* o the original line
* -> Return 1
* 3. The point is in the line
* -> Push 2 elements on the collection:
* o start_point - cut_point
* o cut_point - last_point
* -> Return 2
*/
getPoint4d_p(blade_in->point, 0, &pt);
loc = ptarray_locate_point(lwline_in->points, &pt, &dist, &pt_projected);
/* lwnotice("Location: %g -- Distance: %g", loc, dist); */
if ( dist > 0 ) /* TODO: accept a tolerance ? */
{
/* No intersection */
return 0;
}
if ( loc == 0 || loc == 1 )
{
/* Intersection is on the boundary */
return 1;
}
/* There is a real intersection, let's get two substrings */
/* Compute vertex snap tolerance based on line length
* TODO: take as parameter ? */
vstol = ptarray_length_2d(lwline_in->points) / 1e14;
pa1 = ptarray_substring(lwline_in->points, 0, loc, vstol);
pa2 = ptarray_substring(lwline_in->points, loc, 1, vstol);
/* NOTE: I've seen empty pointarrays with loc != 0 and loc != 1 */
if ( pa1->npoints == 0 || pa2->npoints == 0 ) {
ptarray_free(pa1);
ptarray_free(pa2);
/* Intersection is on the boundary */
return 1;
}
lwmline_add_lwline(v, lwline_construct(SRID_UNKNOWN, NULL, pa1));
lwmline_add_lwline(v, lwline_construct(SRID_UNKNOWN, NULL, pa2));
return 2;
}
Datum LWGEOM_line_interpolate_point(PG_FUNCTION_ARGS)
{
GSERIALIZED *geom = (GSERIALIZED *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
double distance = PG_GETARG_FLOAT8(1);
LWLINE *line;
LWPOINT *point;
POINTARRAY *ipa, *opa;
POINT4D pt;
int nsegs, i;
double length, slength, tlength;
if ( distance < 0 || distance > 1 )
{
elog(ERROR,"line_interpolate_point: 2nd arg isnt within [0,1]");
PG_RETURN_NULL();
}
if ( gserialized_get_type(geom) != LINETYPE )
{
elog(ERROR,"line_interpolate_point: 1st arg isnt a line");
PG_RETURN_NULL();
}
line = lwgeom_as_lwline(lwgeom_from_gserialized(geom));
ipa = line->points;
/* If distance is one of the two extremes, return the point on that
* end rather than doing any expensive computations
*/
if ( distance == 0.0 || distance == 1.0 )
{
if ( distance == 0.0 )
getPoint4d_p(ipa, 0, &pt);
else
getPoint4d_p(ipa, ipa->npoints-1, &pt);
opa = ptarray_construct_reference_data(FLAGS_GET_Z(line->flags), FLAGS_GET_M(line->flags), 1, (uint8_t*)&pt);
point = lwpoint_construct(line->srid, NULL, opa);
PG_RETURN_POINTER(geometry_serialize(lwpoint_as_lwgeom(point)));
}
/* Interpolate a point on the line */
nsegs = ipa->npoints - 1;
length = ptarray_length_2d(ipa);
tlength = 0;
for ( i = 0; i < nsegs; i++ )
{
POINT4D p1, p2;
POINT4D *p1ptr=&p1, *p2ptr=&p2; /* don't break
* strict-aliasing rules
*/
getPoint4d_p(ipa, i, &p1);
getPoint4d_p(ipa, i+1, &p2);
/* Find the relative length of this segment */
slength = distance2d_pt_pt((POINT2D*)p1ptr, (POINT2D*)p2ptr)/length;
/* If our target distance is before the total length we've seen
* so far. create a new point some distance down the current
* segment.
*/
if ( distance < tlength + slength )
{
double dseg = (distance - tlength) / slength;
interpolate_point4d(&p1, &p2, &pt, dseg);
opa = ptarray_construct_reference_data(FLAGS_GET_Z(line->flags), FLAGS_GET_M(line->flags), 1, (uint8_t*)&pt);
point = lwpoint_construct(line->srid, NULL, opa);
PG_RETURN_POINTER(geometry_serialize(lwpoint_as_lwgeom(point)));
}
tlength += slength;
}
/* Return the last point on the line. This shouldn't happen, but
* could if there's some floating point rounding errors. */
getPoint4d_p(ipa, ipa->npoints-1, &pt);
opa = ptarray_construct_reference_data(FLAGS_GET_Z(line->flags), FLAGS_GET_M(line->flags), 1, (uint8_t*)&pt);
point = lwpoint_construct(line->srid, NULL, opa);
PG_RETURN_POINTER(geometry_serialize(lwpoint_as_lwgeom(point)));
}
Datum LWGEOM_line_substring(PG_FUNCTION_ARGS)
{
GSERIALIZED *geom = (GSERIALIZED *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
double from = PG_GETARG_FLOAT8(1);
double to = PG_GETARG_FLOAT8(2);
LWGEOM *olwgeom;
POINTARRAY *ipa, *opa;
GSERIALIZED *ret;
int type = gserialized_get_type(geom);
if ( from < 0 || from > 1 )
{
elog(ERROR,"line_interpolate_point: 2nd arg isnt within [0,1]");
PG_RETURN_NULL();
}
if ( to < 0 || to > 1 )
{
elog(ERROR,"line_interpolate_point: 3rd arg isnt within [0,1]");
PG_RETURN_NULL();
}
if ( from > to )
{
elog(ERROR, "2nd arg must be smaller then 3rd arg");
PG_RETURN_NULL();
}
if ( type == LINETYPE )
{
LWLINE *iline = lwgeom_as_lwline(lwgeom_from_gserialized(geom));
if ( lwgeom_is_empty((LWGEOM*)iline) )
{
/* TODO return empty line */
lwline_release(iline);
PG_FREE_IF_COPY(geom, 0);
PG_RETURN_NULL();
}
ipa = iline->points;
opa = ptarray_substring(ipa, from, to, 0);
if ( opa->npoints == 1 ) /* Point returned */
olwgeom = (LWGEOM *)lwpoint_construct(iline->srid, NULL, opa);
else
olwgeom = (LWGEOM *)lwline_construct(iline->srid, NULL, opa);
}
else if ( type == MULTILINETYPE )
{
LWMLINE *iline;
int i = 0, g = 0;
int homogeneous = LW_TRUE;
LWGEOM **geoms = NULL;
double length = 0.0, sublength = 0.0, minprop = 0.0, maxprop = 0.0;
iline = lwgeom_as_lwmline(lwgeom_from_gserialized(geom));
if ( lwgeom_is_empty((LWGEOM*)iline) )
{
/* TODO return empty collection */
lwmline_release(iline);
PG_FREE_IF_COPY(geom, 0);
PG_RETURN_NULL();
}
/* Calculate the total length of the mline */
for ( i = 0; i < iline->ngeoms; i++ )
{
LWLINE *subline = (LWLINE*)iline->geoms[i];
if ( subline->points && subline->points->npoints > 1 )
length += ptarray_length_2d(subline->points);
}
geoms = lwalloc(sizeof(LWGEOM*) * iline->ngeoms);
/* Slice each sub-geometry of the multiline */
for ( i = 0; i < iline->ngeoms; i++ )
{
LWLINE *subline = (LWLINE*)iline->geoms[i];
double subfrom = 0.0, subto = 0.0;
if ( subline->points && subline->points->npoints > 1 )
sublength += ptarray_length_2d(subline->points);
/* Calculate proportions for this subline */
minprop = maxprop;
maxprop = sublength / length;
/* This subline doesn't reach the lowest proportion requested
or is beyond the highest proporton */
if ( from > maxprop || to < minprop )
continue;
if ( from <= minprop )
subfrom = 0.0;
if ( to >= maxprop )
subto = 1.0;
if ( from > minprop && from <= maxprop )
subfrom = (from - minprop) / (maxprop - minprop);
if ( to < maxprop && to >= minprop )
subto = (to - minprop) / (maxprop - minprop);
opa = ptarray_substring(subline->points, subfrom, subto, 0);
if ( opa && opa->npoints > 0 )
{
if ( opa->npoints == 1 ) /* Point returned */
{
geoms[g] = (LWGEOM *)lwpoint_construct(iline->srid, NULL, opa);
homogeneous = LW_FALSE;
}
else
{
geoms[g] = (LWGEOM *)lwline_construct(iline->srid, NULL, opa);
}
g++;
}
}
/* If we got any points, we need to return a GEOMETRYCOLLECTION */
if ( ! homogeneous )
type = COLLECTIONTYPE;
olwgeom = (LWGEOM*)lwcollection_construct(type, iline->srid, NULL, g, geoms);
}
else
{
elog(ERROR,"line_interpolate_point: 1st arg isnt a line");
PG_RETURN_NULL();
}
ret = geometry_serialize(olwgeom);
lwgeom_free(olwgeom);
PG_FREE_IF_COPY(geom, 0);
PG_RETURN_POINTER(ret);
}
/*
* Given a point, returns the location of closest point on pointarray
* and, optionally, it's actual distance from the point array.
*/
double
ptarray_locate_point(const POINTARRAY *pa, const POINT4D *p4d, double *mindistout, POINT4D *proj4d)
{
double mindist=-1;
double tlen, plen;
int t, seg=-1;
POINT4D start4d, end4d, projtmp;
POINT2D start, end, proj, p;
/* Initialize our 2D copy of the input parameter */
p.x = p4d->x;
p.y = p4d->y;
if ( ! proj4d ) proj4d = &projtmp;
getPoint2d_p(pa, 0, &start);
for (t=1; t<pa->npoints; t++)
{
double dist;
getPoint2d_p(pa, t, &end);
dist = distance2d_pt_seg(&p, &start, &end);
if (t==1 || dist < mindist )
{
mindist = dist;
seg=t-1;
}
if ( mindist == 0 )
{
LWDEBUG(3, "Breaking on mindist=0");
break;
}
start = end;
}
if ( mindistout ) *mindistout = mindist;
LWDEBUGF(3, "Closest segment: %d", seg);
LWDEBUGF(3, "mindist: %g", mindist);
/*
* We need to project the
* point on the closest segment.
*/
getPoint4d_p(pa, seg, &start4d);
getPoint4d_p(pa, seg+1, &end4d);
closest_point_on_segment(p4d, &start4d, &end4d, proj4d);
/* Copy 4D values into 2D holder */
proj.x = proj4d->x;
proj.y = proj4d->y;
LWDEBUGF(3, "Closest segment:%d, npoints:%d", seg, pa->npoints);
/* For robustness, force 1 when closest point == endpoint */
if ( (seg >= (pa->npoints-2)) && p2d_same(&proj, &end) )
{
return 1.0;
}
LWDEBUGF(3, "Closest point on segment: %g,%g", proj.x, proj.y);
tlen = ptarray_length_2d(pa);
LWDEBUGF(3, "tlen %g", tlen);
/* Location of any point on a zero-length line is 0 */
/* See http://trac.osgeo.org/postgis/ticket/1772#comment:2 */
if ( tlen == 0 ) return 0;
plen=0;
getPoint2d_p(pa, 0, &start);
for (t=0; t<seg; t++, start=end)
{
getPoint2d_p(pa, t+1, &end);
plen += distance2d_pt_pt(&start, &end);
LWDEBUGF(4, "Segment %d made plen %g", t, plen);
}
plen+=distance2d_pt_pt(&proj, &start);
LWDEBUGF(3, "plen %g, tlen %g", plen, tlen);
return plen/tlen;
}
POINTARRAY *
ptarray_substring(POINTARRAY *ipa, double from, double to, double tolerance)
{
POINTARRAY *dpa;
POINT4D pt;
POINT4D p1, p2;
POINT4D *p1ptr=&p1; /* don't break strict-aliasing rule */
POINT4D *p2ptr=&p2;
int nsegs, i;
double length, slength, tlength;
int state = 0; /* 0=before, 1=inside */
/*
* Create a dynamic pointarray with an initial capacity
* equal to full copy of input points
*/
dpa = ptarray_construct_empty(FLAGS_GET_Z(ipa->flags), FLAGS_GET_M(ipa->flags), ipa->npoints);
/* Compute total line length */
length = ptarray_length_2d(ipa);
LWDEBUGF(3, "Total length: %g", length);
/* Get 'from' and 'to' lengths */
from = length*from;
to = length*to;
LWDEBUGF(3, "From/To: %g/%g", from, to);
tlength = 0;
getPoint4d_p(ipa, 0, &p1);
nsegs = ipa->npoints - 1;
for ( i = 0; i < nsegs; i++ )
{
double dseg;
getPoint4d_p(ipa, i+1, &p2);
LWDEBUGF(3 ,"Segment %d: (%g,%g,%g,%g)-(%g,%g,%g,%g)",
i, p1.x, p1.y, p1.z, p1.m, p2.x, p2.y, p2.z, p2.m);
/* Find the length of this segment */
slength = distance2d_pt_pt((POINT2D *)p1ptr, (POINT2D *)p2ptr);
/*
* We are before requested start.
*/
if ( state == 0 ) /* before */
{
LWDEBUG(3, " Before start");
if ( fabs ( from - ( tlength + slength ) ) <= tolerance )
{
LWDEBUG(3, " Second point is our start");
/*
* Second point is our start
*/
ptarray_append_point(dpa, &p2, LW_FALSE);
state=1; /* we're inside now */
goto END;
}
else if ( fabs(from - tlength) <= tolerance )
{
LWDEBUG(3, " First point is our start");
/*
* First point is our start
*/
ptarray_append_point(dpa, &p1, LW_FALSE);
/*
* We're inside now, but will check
* 'to' point as well
*/
state=1;
}
/*
* Didn't reach the 'from' point,
* nothing to do
*/
else if ( from > tlength + slength ) goto END;
else /* tlength < from < tlength+slength */
{
LWDEBUG(3, " Seg contains first point");
/*
* Our start is between first and
* second point
*/
dseg = (from - tlength) / slength;
interpolate_point4d(&p1, &p2, &pt, dseg);
ptarray_append_point(dpa, &pt, LW_FALSE);
/*
* We're inside now, but will check
* 'to' point as well
*/
state=1;
}
}
if ( state == 1 ) /* inside */
{
LWDEBUG(3, " Inside");
/*
* 'to' point is our second point.
*/
if ( fabs(to - ( tlength + slength ) ) <= tolerance )
{
LWDEBUG(3, " Second point is our end");
ptarray_append_point(dpa, &p2, LW_FALSE);
break; /* substring complete */
}
/*
* 'to' point is our first point.
* (should only happen if 'to' is 0)
*/
else if ( fabs(to - tlength) <= tolerance )
{
LWDEBUG(3, " First point is our end");
ptarray_append_point(dpa, &p1, LW_FALSE);
break; /* substring complete */
}
/*
* Didn't reach the 'end' point,
* just copy second point
*/
else if ( to > tlength + slength )
{
ptarray_append_point(dpa, &p2, LW_FALSE);
goto END;
}
/*
* 'to' point falls on this segment
* Interpolate and break.
*/
else if ( to < tlength + slength )
{
LWDEBUG(3, " Seg contains our end");
dseg = (to - tlength) / slength;
interpolate_point4d(&p1, &p2, &pt, dseg);
ptarray_append_point(dpa, &pt, LW_FALSE);
break;
}
else
{
LWDEBUG(3, "Unhandled case");
}
}
END:
tlength += slength;
memcpy(&p1, &p2, sizeof(POINT4D));
}
LWDEBUGF(3, "Out of loop, ptarray has %d points", dpa->npoints);
return dpa;
}
