PostGIS  2.5.0beta1dev-r@@SVN_REVISION@@

◆ project_point_on_plane()

double project_point_on_plane ( POINT3DZ p,
PLANE3D pl,
POINT3DZ p0 
)

Finds a point on a plane from where the original point is perpendicular to the plane.

Definition at line 1200 of file measures3d.c.

References DOT, get_3dvector_from_points(), LW_FALSE, PLANE3D::pop, PLANE3D::pv, VECTOR3D::x, POINT3DZ::x, VECTOR3D::y, POINT3DZ::y, VECTOR3D::z, and POINT3DZ::z.

Referenced by lw_dist3d_point_poly(), and lw_dist3d_ptarray_poly().

1201 {
1202 /*In our plane definition we have a point on the plane and a normal vector (pl.pv), perpendicular to the plane
1203 this vector will be parallel to the line between our inputted point above the plane and the point we are searching for on the plane.
1204 So, we already have a direction from p to find p0, but we don't know the distance.
1205 */
1206 
1207  VECTOR3D v1;
1208  double f;
1209 
1210  if (!get_3dvector_from_points(&(pl->pop), p, &v1))
1211  return LW_FALSE;
1212 
1213  f=-(DOT(pl->pv,v1)/DOT(pl->pv,pl->pv));
1214 
1215  p0->x=p->x+pl->pv.x*f;
1216  p0->y=p->y+pl->pv.y*f;
1217  p0->z=p->z+pl->pv.z*f;
1218 
1219  return f;
1220 }
double z
Definition: liblwgeom.h:336
double y
Definition: liblwgeom.h:336
double x
Definition: liblwgeom.h:336
double z
Definition: measures3d.h:51
VECTOR3D pv
Definition: measures3d.h:58
double y
Definition: measures3d.h:51
#define DOT(u, v)
Definition: measures3d.h:31
#define LW_FALSE
Definition: liblwgeom.h:76
static int get_3dvector_from_points(POINT3DZ *p1, POINT3DZ *p2, VECTOR3D *v)
Definition: measures3d.c:45
POINT3DZ pop
Definition: measures3d.h:57
double x
Definition: measures3d.h:51
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