int
lwline_split_by_point_to(const LWLINE* lwline_in, const LWPOINT* blade_in,
LWMLINE* v)
{
double mindist = -1;
POINT4D pt, pt_projected;
POINT4D p1, p2;
POINTARRAY *ipa = lwline_in->points;
POINTARRAY* pa1;
POINTARRAY* pa2;
int i, nsegs, seg = -1;
/* 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
* -> Leave collection untouched, 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);
/* Find closest segment */
getPoint4d_p(ipa, 0, &p1);
nsegs = ipa->npoints - 1;
for ( i = 0; i < nsegs; i++ )
{
getPoint4d_p(ipa, i+1, &p2);
double dist;
dist = distance2d_pt_seg((POINT2D*)&pt, (POINT2D*)&p1, (POINT2D*)&p2);
LWDEBUGF(4, " Distance of point %g %g to segment %g %g, %g %g: %g", pt.x, pt.y, p1.x, p1.y, p2.x, p2.y, dist);
if (i==0 || dist < mindist )
{
mindist = dist;
seg=i;
if ( mindist == 0.0 ) break; /* can't be closer than ON line */
}
p1 = p2;
}
LWDEBUGF(3, "Closest segment: %d", seg);
LWDEBUGF(3, "mindist: %g", mindist);
/* No intersection */
if ( mindist > 0 ) return 0;
/* empty or single-point line, intersection on boundary */
if ( seg < 0 ) return 1;
/*
* We need to project the
* point on the closest segment,
* to interpolate Z and M if needed
*/
getPoint4d_p(ipa, seg, &p1);
getPoint4d_p(ipa, seg+1, &p2);
closest_point_on_segment(&pt, &p1, &p2, &pt_projected);
/* But X and Y we want the ones of the input point,
* as on some architectures the interpolation math moves the
* coordinates (see #3422)
*/
pt_projected.x = pt.x;
pt_projected.y = pt.y;
LWDEBUGF(3, "Projected point:(%g %g), seg:%d, p1:(%g %g), p2:(%g %g)", pt_projected.x, pt_projected.y, seg, p1.x, p1.y, p2.x, p2.y);
/* When closest point == an endpoint, this is a boundary intersection */
if ( ( (seg == nsegs-1) && p4d_same(&pt_projected, &p2) ) ||
( (seg == 0) && p4d_same(&pt_projected, &p1) ) )
{
return 1;
}
/* This is an internal intersection, let's build the two new pointarrays */
pa1 = ptarray_construct_empty(FLAGS_GET_Z(ipa->flags), FLAGS_GET_M(ipa->flags), seg+2);
/* TODO: replace with a memcpy ? */
for (i=0; i<=seg; ++i)
{
getPoint4d_p(ipa, i, &p1);
ptarray_append_point(pa1, &p1, LW_FALSE);
}
ptarray_append_point(pa1, &pt_projected, LW_FALSE);
pa2 = ptarray_construct_empty(FLAGS_GET_Z(ipa->flags), FLAGS_GET_M(ipa->flags), ipa->npoints-seg);
ptarray_append_point(pa2, &pt_projected, LW_FALSE);
/* TODO: replace with a memcpy (if so need to check for duplicated point) ? */
for (i=seg+1; i<ipa->npoints; ++i)
{
getPoint4d_p(ipa, i, &p1);
ptarray_append_point(pa2, &p1, LW_FALSE);
}
/* 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;
}
/*
* 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;
}
