PostGIS  3.1.6dev-r@@SVN_REVISION@@

◆ ptarray_grid_in_place()

void ptarray_grid_in_place ( POINTARRAY pa,
const gridspec grid 
)

Snap to grid.

Definition at line 2016 of file ptarray.c.

2017 {
2018  uint32_t j = 0;
2019  POINT4D *p, *p_out = NULL;
2020  double x, y, z = 0, m = 0;
2021  uint32_t ndims = FLAGS_NDIMS(pa->flags);
2022  uint32_t has_z = FLAGS_GET_Z(pa->flags);
2023  uint32_t has_m = FLAGS_GET_M(pa->flags);
2024 
2025  for (uint32_t i = 0; i < pa->npoints; i++)
2026  {
2027  /* Look straight into the abyss */
2028  p = (POINT4D *)(getPoint_internal(pa, i));
2029  x = p->x;
2030  y = p->y;
2031  if (ndims > 2)
2032  z = p->z;
2033  if (ndims > 3)
2034  m = p->m;
2035 
2036  if (grid->xsize > 0)
2037  x = rint((x - grid->ipx) / grid->xsize) * grid->xsize + grid->ipx;
2038 
2039  if (grid->ysize > 0)
2040  y = rint((y - grid->ipy) / grid->ysize) * grid->ysize + grid->ipy;
2041 
2042  /* Read and round this point */
2043  /* Z is always in third position */
2044  if (has_z && grid->zsize > 0)
2045  z = rint((z - grid->ipz) / grid->zsize) * grid->zsize + grid->ipz;
2046 
2047  /* M might be in 3rd or 4th position */
2048  if (has_m && grid->msize > 0)
2049  {
2050  /* In POINT ZM, M is in 4th position, in POINT M, M is in 3rd position which is Z in POINT4D */
2051  if (has_z)
2052  m = rint((m - grid->ipm) / grid->msize) * grid->msize + grid->ipm;
2053  else
2054  z = rint((z - grid->ipm) / grid->msize) * grid->msize + grid->ipm;
2055  }
2056 
2057  /* Skip duplicates */
2058  if (p_out && p_out->x == x && p_out->y == y && (ndims > 2 ? p_out->z == z : 1) &&
2059  (ndims > 3 ? p_out->m == m : 1))
2060  continue;
2061 
2062  /* Write rounded values into the next available point */
2063  p_out = (POINT4D *)(getPoint_internal(pa, j++));
2064  p_out->x = x;
2065  p_out->y = y;
2066  if (ndims > 2)
2067  p_out->z = z;
2068  if (ndims > 3)
2069  p_out->m = m;
2070  }
2071 
2072  /* Update output ptarray length */
2073  pa->npoints = j;
2074  return;
2075 }
#define FLAGS_GET_Z(flags)
Definition: liblwgeom.h:179
#define FLAGS_NDIMS(flags)
Definition: liblwgeom.h:193
#define FLAGS_GET_M(flags)
Definition: liblwgeom.h:180
static uint8_t * getPoint_internal(const POINTARRAY *pa, uint32_t n)
Definition: lwinline.h:77
double m
Definition: liblwgeom.h:428
double x
Definition: liblwgeom.h:428
double z
Definition: liblwgeom.h:428
double y
Definition: liblwgeom.h:428
lwflags_t flags
Definition: liblwgeom.h:445
uint32_t npoints
Definition: liblwgeom.h:441
double ipm
Definition: liblwgeom.h:1370
double zsize
Definition: liblwgeom.h:1373
double ysize
Definition: liblwgeom.h:1372
double xsize
Definition: liblwgeom.h:1371
double ipx
Definition: liblwgeom.h:1367
double msize
Definition: liblwgeom.h:1374
double ipy
Definition: liblwgeom.h:1368
double ipz
Definition: liblwgeom.h:1369

References POINTARRAY::flags, FLAGS_GET_M, FLAGS_GET_Z, FLAGS_NDIMS, getPoint_internal(), gridspec_t::ipm, gridspec_t::ipx, gridspec_t::ipy, gridspec_t::ipz, POINT4D::m, gridspec_t::msize, POINTARRAY::npoints, POINT4D::x, pixval::x, gridspec_t::xsize, POINT4D::y, pixval::y, gridspec_t::ysize, POINT4D::z, and gridspec_t::zsize.

Referenced by lwgeom_grid_in_place().

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