PostGIS  2.3.7dev-r@@SVN_REVISION@@
static POINTARRAYSET ptarray_locate_between_m ( POINTARRAY ipa,
double  m0,
double  m1 
)
static

Definition at line 436 of file lwgeom_functions_lrs.c.

References clip_seg_by_m_range(), POINTARRAY::flags, FLAGS_GET_M, FLAGS_GET_Z, getPoint4d_p(), LW_FALSE, LW_TRUE, lwalloc(), POINT4D::m, POINTARRAY::npoints, POINTARRAYSET::nptarrays, ptarray_append_point(), ptarray_construct_empty(), POINTARRAYSET::ptarrays, POINT4D::x, POINT4D::y, and POINT4D::z.

Referenced by lwline_locate_between_m().

437 {
438  POINTARRAYSET ret;
439  POINTARRAY *dpa=NULL;
440  int i;
441 
442  ret.nptarrays=0;
443 
444  /*
445  * We allocate space for as many pointarray as
446  * segments in the input POINTARRAY, as worst
447  * case is for each segment to cross the M range
448  * window.
449  * TODO: rework this to reduce used memory
450  */
451  ret.ptarrays=lwalloc(sizeof(POINTARRAY *)*ipa->npoints-1);
452 
453  POSTGIS_DEBUGF(2, "ptarray_locate...: called for pointarray %p, m0:%g, m1:%g",
454  ipa, m0, m1);
455 
456 
457  for (i=1; i<ipa->npoints; i++)
458  {
459  POINT4D p1, p2;
460  int clipval;
461 
462  getPoint4d_p(ipa, i-1, &p1);
463  getPoint4d_p(ipa, i, &p2);
464 
465  POSTGIS_DEBUGF(3, " segment %d-%d [ %g %g %g %g - %g %g %g %g ]",
466  i-1, i,
467  p1.x, p1.y, p1.z, p1.m,
468  p2.x, p2.y, p2.z, p2.m);
469 
470  clipval = clip_seg_by_m_range(&p1, &p2, m0, m1);
471 
472  /* segment completely outside, nothing to do */
473  if (! clipval ) continue;
474 
475  POSTGIS_DEBUGF(3, " clipped to: [ %g %g %g %g - %g %g %g %g ] clipval: %d", p1.x, p1.y, p1.z, p1.m,
476  p2.x, p2.y, p2.z, p2.m, clipval);
477 
478  /* If no points have been accumulated so far, then if clipval != 0 the first point must be the
479  start of the intersection */
480  if (dpa == NULL)
481  {
482  POSTGIS_DEBUGF(3, " 1 creating new POINTARRAY with first point %g,%g,%g,%g", p1.x, p1.y, p1.z, p1.m);
483 
485  ptarray_append_point(dpa, &p1, LW_TRUE);
486  }
487 
488  /* Otherwise always add the next point, avoiding duplicates */
489  if (dpa)
490  ptarray_append_point(dpa, &p2, LW_FALSE);
491 
492  /*
493  * second point has been clipped
494  */
495  if ( clipval & 0x0100 || i == ipa->npoints-1 )
496  {
497  POSTGIS_DEBUGF(3, " closing pointarray %p with %d points", dpa, dpa->npoints);
498 
499  ret.ptarrays[ret.nptarrays++] = dpa;
500  dpa = NULL;
501  }
502  }
503 
504  /*
505  * if dpa!=NULL it means we didn't close it yet.
506  * this should never happen.
507  */
508  if ( dpa != NULL ) lwpgerror("Something wrong with algorithm");
509 
510  return ret;
511 }
double x
Definition: liblwgeom.h:351
double m
Definition: liblwgeom.h:351
int npoints
Definition: liblwgeom.h:370
POINTARRAY * ptarray_construct_empty(char hasz, char hasm, uint32_t maxpoints)
Create a new POINTARRAY with no points.
Definition: ptarray.c:70
POINTARRAY ** ptarrays
int ptarray_append_point(POINTARRAY *pa, const POINT4D *pt, int allow_duplicates)
Append a point to the end of an existing POINTARRAY If allow_duplicate is LW_FALSE, then a duplicate point will not be added.
Definition: ptarray.c:156
#define LW_FALSE
Definition: liblwgeom.h:76
uint8_t flags
Definition: liblwgeom.h:368
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:75
#define FLAGS_GET_Z(flags)
Macros for manipulating the 'flags' byte.
Definition: liblwgeom.h:139
double z
Definition: liblwgeom.h:351
#define FLAGS_GET_M(flags)
Definition: liblwgeom.h:140
void * lwalloc(size_t size)
Definition: lwutil.c:227
double y
Definition: liblwgeom.h:351
int getPoint4d_p(const POINTARRAY *pa, int n, POINT4D *point)
Definition: lwgeom_api.c:244
static int clip_seg_by_m_range(POINT4D *p1, POINT4D *p2, double m0, double m1)

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