PK_NABOX_sf_t

struct PK_NABOX_sf_s
     {
     PK_AXIS2_sf_t basis_set;    --- coordinate system for box
     PK_BOX_t      box;          --- box
     };
typedef struct PK_NABOX_sf_s PK_NABOX_sf_t;


This data structure is the standard form for a non-aligned box.

Used in:

PK_LATTICE_find_nabox_r_t
PK_TOPOL_facet_mesh_2_o_t
PK_TOPOL_facet_mesh_o_t
PK_TOPOL_find_nabox
PK_TOPOL_render_line_o_t

A non-aligned box is a cuboid space defined by an origin, a pair of orthogonal
axes (normalised direction vectors) and a set of x, y, z intervals. The term
`non-aligned' means the box axes need not be aligned with the model space axes.

The local Z direction is given through the 'axis' field of 'basis_set'.

The local X direction is given through the 'ref_direction' field of
'basis_set'.

The local Y direction is formed from the cross product of the local Z
direction and the local X direction.

These form a right handed coordinate system.

                                y
                                |
                                |
                               / \
                              /   \
                     (axis) z/     \x (ref_direction)

The associated box is defined in this local coordinate system.
Its extent is defined by x, y and z intervals.