PK_ERROR_code_t PK_BODY_thicken
(
--- received arguments ---
PK_BODY_t body, --- sheet body to be thickened
double front, --- thickness on front of face
double back, --- thickness on back of face
double tolerance, --- tolerance for SP-curve conversion
PK_LOGICAL_t face_face_check, --- do face face checks
--- returned arguments ---
int *const n_topols, --- number of topols
PK_TOPOL_t **const old_topols, --- original topology (optional)
PK_TOPOL_t **const new_topols --- new topology (optional)
)
Thickens a sheet body into a solid
NOTE: This function is obsolete and has been superseded by
PK_BODY_thicken_2
Specific Errors:
PK_ERROR_cant_thicken thickening failure
PK_ERROR_bad_tolerance proposed edge tolerance is too small
PK_ERROR_not_sheet body is not a sheet body
PK_ERROR_bad_thickness total thickness is zero
PK_ERROR_cant_get_point failed to find vertex geometry
PK_ERROR_cant_get_curve failed to find edge geometry
PK_ERROR_cant_offset surf failed to offset or face could not
be deleted
PK_ERROR_cant_get_side_surf failed to find side surface
PK_ERROR_cant_get_side_curve failed to find side curve
PK_ERROR_point_contact point contact found in sheet body
Introduction
The sheet body is thickened by front outwards (i.e. in the direction of
the face normal) and back inwards. Either front or back may be
negative, but the total thickness must be non-zero.
Only manifold sheet bodies can be thickened.
Some edge geometry on the sheet boundary may have to be approximated by
SP-curves in order to generate a boundary curve on the offset faces. If this
is necessary, such edges will have a tolerance less than or equal to the
tolerance supplied through the tolerance argument.
Two situations can give rise to changes in the topology :
1) Dealing with geometry which fails to offset. If it is known that the
offset surface of a face would be self-intersecting an attempt is made
to remove the face. For example, a blend may be removed from an edge.
The investigation of self-intersection is not exhaustive, however,
and it can occur that instances are not trapped.
2) Dealing with configurations which can be repaired. For instance an
edge may offset to a point or a face become absorbed into the body.
Checking options
The extent to which checking is applied to the body is specified by the
face_face_check argument. If face_face_check is true then
face-face checks are done on the body in addition to default checks.
For most applications setting face_face_check false will give an
adequate level of checking.
Thickening which would lead to a self-intersecting or non-manifold solid is
not allowed. Some of these cases will not be detected when face-face checks
are not done, in this case the resulting body will be invalid.
Table of exact cases
Boundary edges with the following curves on these surfaces will be treated
exactly :
Surface | Curve
-----------------------------------------
Plane | Line, Circle, Ellipse or B-curve
Cylinder | Line, Circle or B-curve equivalent
Cone | Line, Circle or B-curve equivalent
Sphere | Circle
Torus | Circle
Swept Surface or | Line, Profile curve or B-curve equivalent
B-surface equiv |
Spun Surface or | Circle, Profile curve or B-curve equivalent
B-surface equiv |
Cases handled
Thickening only handles the cases where each vertex on the boundary of the
sheet meets one of the following requirements. Either the vertex is smooth
(surface normals constant on all adjoining faces) or both adjoining boundary
edges must have curves of the types treated exactly (see table above) or the
thickening is into the angle of the edge (i.e. convex edges inwards only and
concave edges outwards only).
old_topols and new_topols return args
Each new face in the resulting body will have been generated by either
a face, an exterior edge or a vertex in the original sheet. The pairs
of original faces, edges or vertices and corresponding new faces are
returned in the old_topols and new_topols arguments. Both lists
may contain null tags where faces have vanished. If the total
thickness is positive the tag of a face in the original body will
remain on the front of the resulting body with the same sense
otherwise it will be on the back with the opposite sense.
Error handling
When an error occurs, the function will, where possible, make extra
information regarding the error available to the application
by means of a GROUP.
This GROUP is accessible from the standard form of the error. Note that,
while the members of the GROUP will be objects which existed before the
call (and so will survive rollback), the GROUP itself will be destroyed by
rollback. The members of the GROUP will be as follows:
PK_ERROR_cant_offset 1 FACE Failed to offset or face could
not be deleted
PK_ERROR_cant_get_point 1 VERTEX Failed to find new geometry for
existing vertex
n FACEs Failed to find geometry for
new vertex.
PK_ERROR_cant_get_curve 1 EDGE Failed to find new geometry for
existing edge
n FACEs Failed to find geometry for
new edge
PK_ERROR_cant_get_side_curve 1 VERTEX Failed to find side curve
PK_ERROR_cant_get_side_surf 1 EDGE Failed to find side surface
PK_ERROR_face_check_fails 1 FACE Face which failed check
PK_ERROR_face_face_check_fails 2 FACEs Pair of faces where
inconsistency found.
PK_ERROR_point_contact 1 VERTEX Vertex where point
contact found.
This function is not supported for general bodies.
