CRTSFA ( sf, sense, curves, etol, ftol, nopts, chopts, body, face, state,
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ifail )
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Creates a sheet body given surface and trimmed SP-curve data.
Receives:
KI_tag_surface *sf --- surface of face
KI_cod_logical *sense --- sense of face
<KI_tag_list_list> *curves --- curves, one list for each
--- loop of face
double *etol --- 3-space distance tolerance,
--- stored on each edge
double *ftol --- 3-space distance tolerance
--- stored on the face
<KI_int_nitems> *nopts --- number of checking options
<KI_cod_tsop> chopts[nopts] --- checking options
Returns:
<KI_tag_body> *body --- sheet body created
<KI_tag_face> *face --- face of 'by'
KI_cod_rtts *state --- state code
KI_cod_error *ifail --- failure indicator
Specific errors:
KI_bad_sharing sf referenced from other than supplied SP-curves
KI_bad_basis_surf SP-curve not on surface
KI_has_parent underlying SP-curve is not orphan
trimmed curve is not orphan
surface is not orphan
KI_wrong_entity_in_list underlying curve is not an SP-curve
list contained non trimmed curve
KI_duplicate_list_item curve geometry duplicated in lists
KI_unsuitable_entity surface does not pass checks
KI_bad_option_data incorrect checking option data
KI_bad_tolerance face tolerance is less than Parasolid tolerance
edge tolerance is less than Parasolid tolerance
Description:
This function creates a sheet body with a single face, given surface
geometry for the face and curve geometry for the edges.
The topology of the resulting sheet will be inferred from the geometry.
CRTSFA is designed primarily for importing geometric data of lower precision
than Parasolid default. The geometry supplied to the routine need not,
therefore, conform to Parasolid's standard tolerances. The user is responsible
for specifying the distance tolerance parameters, the minimum distance two
points have to be apart to be regarded as distinct, which will be stored
with the face and edges of the resulting sheet body.
'sf' will be the geometry attached to the single face of the body. It
can be of any type recognised by Parasolid, and must be orphan. If
'sf' is a B-surface, it must be capable of passing the continuity
checks imposed by CHCKEN.
'sense' is a logical indicating whether the resultant face normal is aligned
with the surface normal (set to true) or anti-aligned (false).
'curves' is a list containing lists of trimmed curves (type TYCUTR)
representing the edge geometry of the face. The basis curves of the supplied
trimmed curves must always be SP-curves. Each sublist of 'curves' will
contain the SP-curves geometry representing a single loop. 'curves' is not
allowed to be null, except in the case of a wholly closed sheet with no loops
e.g. whole sphere or torus. The trimmed curves will be attached to the fins
of the edges of the created face. Note that each curve appearing in 'curves'
must be orphan, and must reference an underlying SP-curve which is also
orphan.
The curve directions should be such that the intended face lies on the left
of the curve when viewed in a direction opposing the face normal. The
curves should be given in the correct order, following each other around
the loop such that the end of any given curve is within tolerance of the
start of the next one. Minimal corrective action will be attempted for
input data not meeting these requirements, though this cannot be
guaranteed to produce valid loops. The curve ordering must be correct
as no attempt to reorder the curves is made.
Note that CRTSFA can accept any trimmed surface formats supported by OUTSFA,
although it will not incorporate SP-curves representing surface degeneracies
into the model, as these have zero 3-space length. Similarly trimmed SP-curves
shorter than the requisite tolerance (in terms of chord length) will not
appear in the model (trimmed curves whose underlying SP-curve is closed are
excepted).
Note that two coincident opposing curves must be supplied if a wire edge
(corresponding, for example, to a seam on a periodic surface) is required.
In addition, CRTSFA will always create closed loop topology, regardless of
the actual geometric closure of the supplied loops of SP-curves.
All SP-curves satisfy the continuity requirements described under CRSPCU
before introduction into a model by means of CRTSFA.
The points stored on the vertices of the sheet body will be computed by
Parasolid, so the application has no need to supply them. The position of
the vertex is deemed to be the centroid point of all the trimmed curve ends
meeting at the vertex. A suitable tolerance for the vertex is also computed.
It should be noted that because the vertex point and tolerance are flexible
to some extent, it is not necessary that consecutive trimmed curves meet to
within twice 'etol' at the vertex. As a safeguard against potentially
incorrectly ordered data, however, there will be a state code indicator
returned when any computed vertex tolerance exceeds 10 times 'etol'.
'etol' is a 3-space distance parameter, and will be stored with all of the
edges of the resultant sheet. Refer to SETLEN for the meaning of this
tolerance within a model. From an application point of view, the value of
'etol' will reflect the accuracy of the sending system's curve data, and must
be greater than or equal to Parasolid's linear tolerance. SETLEN can be used
subsequently to modify the tolerance of any edge of the resultant sheet.
'ftol' is again a 3-space distance parameter, and will be stored with the
face of the created sheet. Refer to SETLEN for the meaning of this
tolerance within a model. From the application point of view, the value of
'ftol' will reflect the accuracy of the sending system's surface data. It is
required that 'ftol' be less than or at most equal to 'etol'.
There are three optional levels of checking available on the resulting
sheet body. These can be employed by the application according to how much
is known about the input data in terms of, for example, the consistency of
the loops directions. Whichever option is used, CRTSFA will attempt to
correct any inconsistencies found within the limits imposed by the checks.
Note that each option is independent of the others.
Option TSOPWR. This option allows the identification of wire topologies
(e.g. seamlines) and will ensure that the correct topology is made in such
cases.
Option TSOPSX. This option enables the application to pick up
self-intersections within the sheet. Checks made are:
. All edges are tested pairwise with each other to detect points at which
their fin curves intersect which are NOT model vertices. There is no
possible corrective action that can be taken here. Such sheets will fail
CHCKEN.
Option TSOPLC. This will check that the loops of the face are consistent.
With this option turned on:
. Checks are made to check whether:
. The loops are correctly contained (i.e. all inner hole loops lie within
the boundary or peripheral loop, where such can be determined).
. The combination of loops is a valid one for the surface type (for
example, a set of loops on a plane contains just one peripheral positive
loop and the rest negative hole ones).
. If the above conditions are not met minimal corrective action is attempted.
In an attempt to create valid loops CRTSFA may reverse loops,
and investigate singularities of 'sf' introducing them into the face as
isolated vertices if necessary. This corrective action is only attempted if
the TSOPLC option is turned on, and there no guarantee of valid result
being found.
The resulting sheet is returned in 'body'.
'face' is the single face to which the supplied surface geometry is
attached.
'state' is an indicator of the validity of the sheet after the chosen
checking options have been performed on it. It is not intended to give
detailed information (use CHCKEN for this). The returns are:
RTTSOK. Indicates that either all selected checks passed, and any attempted
corrections were successful, or no checks were requested.
RTTSFR. Face is redundant with respect to the supplied tolerances. This is
because all the supplied curves were too short with respect to 'etol' for
the production of a valid face.
RTTSCI. Indicates that no sense could be made of the input loops of
curves. This means that they did not follow round in the loop direction
as indicated earlier, and there may be vertex tolerances computed as a
result which exceed 10 times 'etol'.
RTTSSX. Indicates that the resultant sheet is self-intersecting because
edges meet at a place other than a model vertex.
RTTSLI. Indicates that the loop structure of the resulting sheet is in
some way invalid (e.g. there is no peripheral loop on a planar surface),
and attempts to correct the problem failed. Such sheets should NOT be
subsequently passed to CRKNPA or KNITEN, or otherwise incorporated into
solid bodies.
RTTSEO. Indicates that the edges of the resulting sheet are incorrectly
ordered at at least one of its vertices. This can be caused by the input data
failing to comply with the convention on wire edges, for example.
