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 569 of file lwgeodetic.c.

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

Referenced by test_vector_rotate().

{
        POINT3D u;
        double cos_a = cos(angle);
        double sin_a = sin(angle);
        double uxuy, uyuz, uxuz;
        double ux2, uy2, uz2;
        double rxx, rxy, rxz, ryx, ryy, ryz, rzx, rzy, rzz;

        /* Need a unit vector normal to rotate around */
        unit_normal(v1, v2, &u);

        uxuy = u.x * u.y;
        uxuz = u.x * u.z;
        uyuz = u.y * u.z;

        ux2 = u.x * u.x;
        uy2 = u.y * u.y;
        uz2 = u.z * u.z;

        rxx = cos_a + ux2 * (1 - cos_a);
        rxy = uxuy * (1 - cos_a) - u.z * sin_a;
        rxz = uxuz * (1 - cos_a) + u.y * sin_a;

        ryx = uxuy * (1 - cos_a) + u.z * sin_a;
        ryy = cos_a + uy2 * (1 - cos_a);
        ryz = uyuz * (1 - cos_a) - u.x * sin_a;

        rzx = uxuz * (1 - cos_a) - u.y * sin_a;
        rzy = uyuz * (1 - cos_a) + u.x * sin_a;
        rzz = cos_a + uz2 * (1 - cos_a);

        n->x = rxx * v1->x + rxy * v1->y + rxz * v1->z;
        n->y = ryx * v1->x + ryy * v1->y + ryz * v1->z;
        n->z = rzx * v1->x + rzy * v1->y + rzz * v1->z;

        normalize(n);
}

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