PostGIS  2.2.8dev-r@@SVN_REVISION@@

◆ lwgeom_interpolate_point()

double lwgeom_interpolate_point ( const LWGEOM lwin,
const LWPOINT lwpt 
)

Find the measure value at the location on the line closest to the point.

Definition at line 838 of file lwlinearreferencing.c.

References LINETYPE, lwerror(), lwgeom_as_lwline(), lwgeom_has_m(), lwgeom_is_empty(), lwpoint_getPoint4d_p(), lwpoint_is_empty(), lwtype_name(), POINT4D::m, LWLINE::points, ptarray_locate_point(), and LWGEOM::type.

Referenced by gserialized_distance_nd(), and ST_InterpolatePoint().

839 {
840  POINT4D p, p_proj;
841  double ret = 0.0;
842 
843  if ( ! lwin )
844  lwerror("lwgeom_interpolate_point: null input geometry!");
845 
846  if ( ! lwgeom_has_m(lwin) )
847  lwerror("Input geometry does not have a measure dimension");
848 
849  if ( lwgeom_is_empty(lwin) || lwpoint_is_empty(lwpt) )
850  lwerror("Input geometry is empty");
851 
852  switch ( lwin->type )
853  {
854  case LINETYPE:
855  {
856  LWLINE *lwline = lwgeom_as_lwline(lwin);
857  lwpoint_getPoint4d_p(lwpt, &p);
858  ret = ptarray_locate_point(lwline->points, &p, NULL, &p_proj);
859  ret = p_proj.m;
860  break;
861  }
862  default:
863  lwerror("This function does not accept %s geometries.", lwtype_name(lwin->type));
864  }
865  return ret;
866 }
#define LINETYPE
Definition: liblwgeom.h:71
double m
Definition: liblwgeom.h:336
double ptarray_locate_point(const POINTARRAY *pa, const POINT4D *pt, double *dist, POINT4D *p_located)
Definition: ptarray.c:1303
const char * lwtype_name(uint8_t type)
Return the type name string associated with a type number (e.g.
Definition: lwutil.c:188
int lwpoint_getPoint4d_p(const LWPOINT *point, POINT4D *out)
Definition: lwpoint.c:44
LWLINE * lwgeom_as_lwline(const LWGEOM *lwgeom)
Definition: lwgeom.c:89
int lwpoint_is_empty(const LWPOINT *point)
Definition: lwpoint.c:260
uint8_t type
Definition: liblwgeom.h:380
int lwgeom_is_empty(const LWGEOM *geom)
Return true or false depending on whether a geometry is an "empty" geometry (no vertices members) ...
Definition: lwgeom.c:1297
int lwgeom_has_m(const LWGEOM *geom)
Return LW_TRUE if geometry has M ordinates.
Definition: lwgeom.c:843
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:74
POINTARRAY * points
Definition: liblwgeom.h:406
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