PostGIS  2.1.10dev-r@@SVN_REVISION@@
void interpolate_point4d ( POINT4D A,
POINT4D B,
POINT4D I,
double  F 
)

Find interpolation point I between point A and point B so that the len(AI) == len(AB)*F and I falls on AB segment.

Example:

F=0.5 : A-—I-—B F=1 : A------—B==I F=0 : A==I------—B F=.2 : A-I----—B

Definition at line 771 of file lwgeom_api.c.

References lwerror(), POINT4D::m, POINT4D::x, POINT4D::y, and POINT4D::z.

Referenced by LWGEOM_line_interpolate_point(), and ptarray_substring().

772 {
773 #if PARANOIA_LEVEL > 0
774  double absF=fabs(F);
775  if ( absF < 0 || absF > 1 )
776  {
777  lwerror("interpolate_point4d: invalid F (%g)", F);
778  }
779 #endif
780  I->x=A->x+((B->x-A->x)*F);
781  I->y=A->y+((B->y-A->y)*F);
782  I->z=A->z+((B->z-A->z)*F);
783  I->m=A->m+((B->m-A->m)*F);
784 }
double x
Definition: liblwgeom.h:308
double m
Definition: liblwgeom.h:308
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:67
double z
Definition: liblwgeom.h:308
double y
Definition: liblwgeom.h:308

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