RRFCET ( nopts, iopts, optdta, entys, transf, ifail )
=====================================================
Generate facetted rendering.
Receives:
<KI_int_nitems> *nopts --- number of options in 'iopts'
KI_cod_rrop iopts[nopts] --- rendering options
<KI_tag_list_dbl> optdta[nopts] --- option data lists
KI_tag_list_entity *entys --- entities to render
<KI_tag_list_<transform>> *transf --- entity transforms
Returns:
KI_cod_error *ifail --- failure indicator
Specific errors:
KI_missing_geom A topological entity has no associated geometry
KI_abort_from_go Rendering aborted by GO
KI_request_not_supported Polygonal body supplied in list
KI_general_body General body supplied in list
KI_wrong_transf Unsuitable transform
KI_bad_view_mx Option data contains invalid view matrix
KI_not_same_length Entity and transform lists are of different lengths
KI_wrong_entity_in_list Entity is not a part or a face
KI_bad_option_data Option data incorrect for specified options
Description:
RRFCET outputs, through the Graphical Output interface (GO), data for a
facetted representation of the entities.
RRFCET can render assemblies, bodies and faces; it cannot render individual
edges. General bodies and faces from general bodies are not supported.
Transforms may only contain translation and rotation components. Reflections,
scales and shears are not allowed.
The data output is selected by options in 'iopts'. For some options the output
is further controlled by data in a real list whose tag is passed in the
corresponding entry in 'optdta'. If no data is required for an option a null
tag should be passed. For those options which require data, a zero value
indicates that the corresponding tolerance or limit is ignored; at least one
value must be non-zero.
Options accepted are:-
Option Contents of option data
===================================================================
RROPTR: TRansform none
RROPNF: No Fitting none
RROPVM: Vertex Matching none
RROPCV: ConVexity none
RROPHO: HOles permitted none
RROPVN: Vertex Normals none
RROPPI: Parameter data none
RROPD1: Derivative data none
RROPD2: Derivative data none
RROPET: Edge Tags none
RROPST: Surface Tolerance (1) Distance tolerance in model units
(2) Angular tolerance in radians
RROPCT: Curve Tolerance (1) Chord tolerance in model units
(2) Maximum chord length in model units
(3) Angular tolerance in radians
RROPFS: Facet Size (1) Maximum number of sides per facet
(2) Maximum width of facet in model units
RROPMF: Minimum Facet Size (1) Minimum size of facet
RROPPT: Planarity Tolerance (1) Distance tolerance in model units
(2) Angular tolerance in radians
RROPFP: Facet Perspective (1-16) Viewing transformation matrix
RROPFI: Facet Infinite (1-16) Viewing transformation matrix
RROPTS: Facet Strips (1) Maximum length of facet strip
RROPIL: Ignore loops (1) Number, n, of loops following
(2-(n+1)) Tags of loops to be ignored
RROPSD: Silhouette Density (1-3) Viewing direction vector
(4-5) Density control
Option RROPTR is required if any of the entities is to be rendered in a
transformed position (e.g. as part of an assembly). If it is not specified,
the contents of 'transf' are ignored, and entities are rendered in their
local coordinate system.
Option RROPNF will not attempt to fit the facets together at the edges of
each face. With this option the facetting algorithm will be faster as
no clipping and matching will be performed at face edges. This may produce
an inconsistent result with overlapping facets or gaps.
Option RROPVM ensures that there are no gaps along model edges and that along
these edges there are no facet vertices which are interior to an adjacent
facet edge. This option only affects whole bodies and assemblies.
Option RROPCV causes the shape of the facet to be limited so that the sides
of the facet form a convex polygon. Each interior angle of a convex polygon
is less than pi radians. A convex polygon contains no holes.
Option RROPHO will allow the facet to be represented with holes in its
interior.
Option RROPVN should be specified if surface normals at the facet vertices
are required.
Option RROPPI should be specified if parameter information at the facet
vertices is required.
Option RROPD1 should be specified if first surface derivatives at the facet
vertices are required. RROPD2 should be specified if first and second
surface derivatives at the facet vertices are required. If either of RROPD1
or RROPD2 is enabled then vertex normals and parameter data will also be
output.
If option RROPET is specified, RRFCET will output an array of edge tags, one
edge tag for each facet edge, indicating the model edges from which the facet
edges are derived. If a facet edge was not derived from the model a null tag
is given.
Option RROPST controls the facetted representation of the entity by
considering the surface approximation. The first value in the option data is a
distance tolerance on a facet. This is an upper bound on the distance from a
position on a facet to the surface. The second value is an angular tolerance
on a facet. This is an upper bound on the angular deviation between the
surface normals at any two positions under the facet. This function will
usually satisfy these tolerances although this is not guaranteed. If this
option is not specified a default angular tolerance is used.
Option RROPCT controls the facetted representation of the entity by
considering the curved edge approximation. A curved edge is approximated by a
number of straight lines called chords. The first value in the option data is
a chord tolerance. This is an upper bound on the distance from each chord to
the curve it is approximating. The second value is a chord limit. This is an
upper bound on the length of a chord used in the approximation of a curved
edge. The third value is an angular tolerance. This limits the angular error
between a curve and a chord used in its approximation. This is an upper bound
on the sum of the two angles formed between the chord and the curve tangent at
each chord end. If this option is not specified a default angular tolerance is
used.
Option RROPFS controls the facetted representation of the entity by
considering the maximum size of the facet. The first value in the option data
specifies the maximum number of sides in a facet. The second value specifies
the maximum width of a facet. If this option is not specified no upper limit on
facet size will be applied.
Option RROPMF controls the facetted representation of the entity by
considering the minimum size of the facet. The value in the option data
specifies a 3-space facet width below which Parasolid may disregard the fact
that facets don't meet the tolerance criteria specified via RROPST, RROPCT or
RROPPT. Facets smaller that this dimension may still be produced, however.
If this option is not specified, Parasolid will choose its own value for the
minimum facet size based on the size of the face box. This avoids the problem
whereby some portions of an entity may require arbitrary subdivision wihout
acheiving a satisfactory facetted representation.
Option RROPPT controls the facetted representation of the entity by
considering the planarity of each facet. The first value in the option data is
a distance tolerance. This is an upper bound on the distance from the facet to
the facet mid-plane. The corners of the facet define the mid-plane which takes
their average normal and passes through their centre of gravity. The second
value is an angular tolerance. This is defined as the ratio of the maximum
separation between facet and mid-plane to maximum width over a facet. If this
option is not specified the facets will be planar within modelling resolution.
If option RROPFP is specified, RRFCET will not generate facets for faces of
solid bodies which can be quickly identified as back-facing in the given
perspective view. This option is available in order to enhance performance; it
does not guarantee to inhibit facetting of all back-facing faces.
If option RROPFI is specified, RRFCET will not generate facets for faces of
solid bodies which can be quickly identified as back-facing in the given view
from infinity. Only the view direction is taken from the view matrix. This
option is available in order to enhance performance; it does not guarantee to
inhibit facetting of all back-facing faces.
If option RROPTS is specified, RRFCET will output strips of triangular
facets whenever possible. The option data value supplied with this
option is the maximum number of facets in each strip. This value must
be supplied and should be at least 2. With this option supplied the
facets will always be triangular and therefore the maximum number of
facet sides supplied with the option RROPFS will be ignored.
If option RROPIL is specified, RRFCET will make no attempt to trim the facetted
representation of the surfaces to the specified loops. The loops must not be
external loops of faces. This option is intended to be used to allow the
facetting of sheet body faces to cover holes in the sheet by specifying the
loops of the holes with this option.
If option RROPSD is specified, RRFCET will increase the density of facets over
regions of the body which are silhouettes if the body is viewed with a parallel
view in the direction specified in the data. The final data elements control
this increase of facet density.
Only one of RROPVM, RROPFP or RROPFI may be selected.
