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/**********************************************************************
*
* PostGIS - Spatial Types for PostgreSQL
* http://postgis.net
*
* PostGIS is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* PostGIS is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with PostGIS. If not, see <http://www.gnu.org/licenses/>.
*
**********************************************************************
*
* Copyright 2018 Nicklas Avén
*
**********************************************************************/
#include "liblwgeom_internal.h"
static POINTARRAY * ptarray_chaikin(POINTARRAY *inpts, int preserve_endpoint, int isclosed)
{
uint32_t p, i, n_out_points=0, p1_set=0, p2_set=0;
POINT4D p1, p2;
POINTARRAY *opts;
double *dlist;
double deltaval, quarter_delta, val1, val2;
uint32_t ndims = 2 + ptarray_has_z(inpts) + ptarray_has_m(inpts);
int new_npoints = inpts->npoints * 2;
opts = ptarray_construct_empty(FLAGS_GET_Z(inpts->flags), FLAGS_GET_M(inpts->flags), new_npoints);
dlist = (double*)(opts->serialized_pointlist);
p1 = getPoint4d(inpts, 0);
/*if first point*/
if(preserve_endpoint)
{
ptarray_append_point(opts, &p1, LW_TRUE);
n_out_points++;
}
for (p=1;p<inpts->npoints;p++)
{
memcpy(&p2, &p1, sizeof(POINT4D));
p1 = getPoint4d(inpts, p);
if(p>0)
{
p1_set = p2_set = 0;
for (i=0;i<ndims;i++)
{
val1 = ((double*) &(p1))[i];
val2 = ((double*) &(p2))[i];
deltaval = val1 - val2;
quarter_delta = deltaval * 0.25;
if(!preserve_endpoint || p > 1)
{
dlist[n_out_points * ndims + i] = val2 + quarter_delta;
p1_set = 1;
}
if(!preserve_endpoint || p < inpts->npoints - 1)
{
dlist[(n_out_points + p1_set) * ndims + i] = val1 - quarter_delta;
p2_set = 1;
}
}
n_out_points+=(p1_set + p2_set);
}
}
/*if last point*/
if(preserve_endpoint)
{
opts->npoints = n_out_points;
ptarray_append_point(opts, &p1, LW_TRUE);
n_out_points++;
}
if(isclosed && !preserve_endpoint)
{
opts->npoints = n_out_points;
POINT4D first_point = getPoint4d(opts, 0);
ptarray_append_point(opts, &first_point, LW_TRUE);
n_out_points++;
}
opts->npoints = n_out_points;
return opts;
}
static LWLINE* lwline_chaikin(const LWLINE *iline, int n_iterations)
{
POINTARRAY *pa, *pa_new;
int j;
LWLINE *oline;
if( lwline_is_empty(iline))
return lwline_clone(iline);
pa = iline->points;
for (j=0;j<n_iterations;j++)
{
pa_new = ptarray_chaikin(pa,1,LW_FALSE);
if(j>0)
ptarray_free(pa);
pa=pa_new;
}
oline = lwline_construct(iline->srid, NULL, pa);
oline->type = iline->type;
return oline;
}
static LWPOLY* lwpoly_chaikin(const LWPOLY *ipoly, int n_iterations, int preserve_endpoint)
{
uint32_t i;
int j;
POINTARRAY *pa, *pa_new;
LWPOLY *opoly = lwpoly_construct_empty(ipoly->srid, FLAGS_GET_Z(ipoly->flags), FLAGS_GET_M(ipoly->flags));
if( lwpoly_is_empty(ipoly) )
return opoly;
for (i = 0; i < ipoly->nrings; i++)
{
pa = ipoly->rings[i];
for(j=0;j<n_iterations;j++)
{
pa_new = ptarray_chaikin(pa,preserve_endpoint,LW_TRUE);
if(j>0)
ptarray_free(pa);
pa=pa_new;
}
if(pa->npoints>=4)
{
if( lwpoly_add_ring(opoly,pa ) == LW_FAILURE )
return NULL;
}
}
opoly->type = ipoly->type;
if( lwpoly_is_empty(opoly) )
return NULL;
return opoly;
}
static LWCOLLECTION* lwcollection_chaikin(const LWCOLLECTION *igeom, int n_iterations, int preserve_endpoint)
{
LWDEBUG(2, "Entered lwcollection_set_effective_area");
uint32_t i;
LWCOLLECTION *out = lwcollection_construct_empty(igeom->type, igeom->srid, FLAGS_GET_Z(igeom->flags), FLAGS_GET_M(igeom->flags));
if( lwcollection_is_empty(igeom) )
return out; /* should we return NULL instead ? */
for( i = 0; i < igeom->ngeoms; i++ )
{
LWGEOM *ngeom = lwgeom_chaikin(igeom->geoms[i],n_iterations,preserve_endpoint);
if ( ngeom ) out = lwcollection_add_lwgeom(out, ngeom);
}
return out;
}
LWGEOM* lwgeom_chaikin(const LWGEOM *igeom, int n_iterations, int preserve_endpoint)
{
LWDEBUG(2, "Entered lwgeom_set_effective_area");
switch (igeom->type)
{
case POINTTYPE:
case MULTIPOINTTYPE:
return lwgeom_clone(igeom);
case LINETYPE:
return (LWGEOM*)lwline_chaikin((LWLINE*)igeom, n_iterations);
case POLYGONTYPE:
return (LWGEOM*)lwpoly_chaikin((LWPOLY*)igeom,n_iterations,preserve_endpoint);
case MULTILINETYPE:
case MULTIPOLYGONTYPE:
case COLLECTIONTYPE:
return (LWGEOM*)lwcollection_chaikin((LWCOLLECTION *)igeom,n_iterations,preserve_endpoint);
default:
lwerror("lwgeom_chaikin: unsupported geometry type: %s",lwtype_name(igeom->type));
}
return NULL;
}
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