PostGIS  2.4.9dev-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 1237 of file measures3d.c.

Referenced by lw_dist3d_point_poly(), and lw_dist3d_ptarray_poly().

1238 {
1239 /*In our plane definition we have a point on the plane and a normal vektor (pl.pv), perpendicular to the plane
1240 this vector will be paralell to the line between our inputted point above the plane and the point we are searching for on the plane.
1241 So, we already have a direction from p to find p0, but we don't know the distance.
1242 */
1243
1244  VECTOR3D v1;
1245  double f;
1246
1247  if (!get_3dvector_from_points(&(pl->pop), p, &v1))
1248  return 0.0;
1249
1250  f = DOT(pl->pv, v1);
1251  if (FP_IS_ZERO(f))
1252  {
1253  /* Point is in the plane */
1254  *p0 = *p;
1255  return 0;
1256  }
1257
1258  f = -f / DOT(pl->pv, pl->pv);
1259
1260  p0->x = p->x + pl->pv.x * f;
1261  p0->y = p->y + pl->pv.y * f;
1262  p0->z = p->z + pl->pv.z * f;
1263
1264  return f;
1265 }
double z
Definition: liblwgeom.h:334
double y
Definition: liblwgeom.h:334
double x
Definition: liblwgeom.h:334
double z
Definition: measures3d.h:51
VECTOR3D pv
Definition: measures3d.h:58
#define FP_IS_ZERO(A)
double y
Definition: measures3d.h:51
#define DOT(u, v)
Definition: measures3d.h:31
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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