PostGIS  2.5.7dev-r@@SVN_REVISION@@

## ◆ vector_rotate()

 void vector_rotate ( const POINT3D * v1, const POINT3D * v2, double angle, POINT3D * n )

Rotates v1 through an angle (in radians) within the plane defined by v1/v2, returns the rotated vector in n.

Definition at line 573 of file lwgeodetic.c.

574 {
575  POINT3D u;
576  double cos_a = cos(angle);
577  double sin_a = sin(angle);
578  double uxuy, uyuz, uxuz;
579  double ux2, uy2, uz2;
580  double rxx, rxy, rxz, ryx, ryy, ryz, rzx, rzy, rzz;
581
582  /* Need a unit vector normal to rotate around */
583  unit_normal(v1, v2, &u);
584
585  uxuy = u.x * u.y;
586  uxuz = u.x * u.z;
587  uyuz = u.y * u.z;
588
589  ux2 = u.x * u.x;
590  uy2 = u.y * u.y;
591  uz2 = u.z * u.z;
592
593  rxx = cos_a + ux2 * (1 - cos_a);
594  rxy = uxuy * (1 - cos_a) - u.z * sin_a;
595  rxz = uxuz * (1 - cos_a) + u.y * sin_a;
596
597  ryx = uxuy * (1 - cos_a) + u.z * sin_a;
598  ryy = cos_a + uy2 * (1 - cos_a);
599  ryz = uyuz * (1 - cos_a) - u.x * sin_a;
600
601  rzx = uxuz * (1 - cos_a) - u.y * sin_a;
602  rzy = uyuz * (1 - cos_a) + u.x * sin_a;
603  rzz = cos_a + uz2 * (1 - cos_a);
604
605  n->x = rxx * v1->x + rxy * v1->y + rxz * v1->z;
606  n->y = ryx * v1->x + ryy * v1->y + ryz * v1->z;
607  n->z = rzx * v1->x + rzy * v1->y + rzz * v1->z;
608
609  normalize(n);
610 }
void normalize(POINT3D *p)
Normalize to a unit vector.
Definition: lwgeodetic.c:615
void unit_normal(const POINT3D *P1, const POINT3D *P2, POINT3D *normal)
Calculates the unit normal to two vectors, trying to avoid problems with over-narrow or over-wide cas...
Definition: lwgeodetic.c:541
double z
Definition: liblwgeom.h:343
double x
Definition: liblwgeom.h:343
double y
Definition: liblwgeom.h:343

References normalize(), unit_normal(), POINT3D::x, POINT3D::y, and POINT3D::z.

Referenced by test_vector_rotate().

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