RRHIDL ( nopts, iopts, optdta, entys, transf, vmatrx, ifail )
=============================================================
Generate hidden line data.
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
KI_dbl_view_mx vmatrx[16] --- viewing transform matrix
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_bad_view_mx Invalid view matrix
KI_wrong_transf Unsuitable transform
KI_not_same_length Entity and transform lists are of different lengths
KI_wrong_entity_in_list Entity is not a part
KI_bad_option_data Option data incorrect for specified options
Description:
RRHIDL outputs, through the Graphical Output interface (GO), data for a
picture of the entities, distinguishing visible from invisible portions.
RRHIDL can only render assemblies and complete bodies; it cannot render
individual faces or edges. Visible edges and silhouette lines are always
output.
Transforms may only contain translation and rotation components. Reflections,
scales and shears are not allowed.
Other 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.
Options accepted are:-
Option Contents of option data
===================================================================
RROPIV: InVisible none
RROPDR: DRafting none
RROPTR: TRansform none
RROPIS: Image Smoothness none
RROPDS: Drafting / Smooth none
edges behaviour
RROPIN: INternal edges none
RROPPC: B-Curve (Bezier) none
RROPNC: B-Curve (Nurbs) none
RROPPS: PerSpective none
RROPRG: ReGional-data none
RROPRA: Regional-Attrib none
RROPPH: Planar-Hatch (1) Planar hatch spacing in model units
(2,3,4) Normal direction of hatch planes
(5,6,7) Plane coordinate (omissible)
RROPRH: Radial-Hatch (1) Hatch spacing in radians around 'spine'
(2) Hatch spacing in model units along 'spine'
(3) Hatch spacing in radians about centre
RROPPA: PAra-Hatch (1) Hatch spacing along u
(2) Hatch spacing along v
RROPCT: Curve Tolerance (1) Chord tolerance in model units
(2) Maximum chord length in model units
(3) Angular tolerance in radians
RROPHR: Hierarchical none
RROPHN: Hierarchical,
no geometry none
RROPHP: Hierarchical,
parametrised none
RROPVP: ViewPort (1,2,3) Centre of viewport in model coordinates
(4,5,6) 1st axis of viewport in model
coordinates
(7,8,9) 2nd axis
(10,11,12) 3rd axis
(13) Length of viewport along 1st axis in model
units
(14) Length along 2nd axis
(15) Length along 3rd axis
Option RROPIV causes data to be output for 'hidden' lines, so that for
example, they can be rendered in a dotted linestyle. By default, data is
only output for visible lines.
Option RROPDR also causes data to be output for 'hidden' lines, but it
distinguishes between lines which are hidden by other lines and those which
are just obscured by other faces of the body, so that, for example, a plot of
the image can be made in which no lines are drawn over the top of other
lines. This option is not available for perspective views (i.e. it cannot be
used with the option RROPPS).
The performance will be degraded if this option is turned on.
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 RROPIS causes the output data for an edge to specify whether or not
the edge is smooth (i.e. the faces have the same tangent surface at the edge)
or smooth but coincident with a silhouette line (which is not output). The
calling program may then choose to omit smooth edges from the final drawing.
If RROPIS is not specified, the smoothness parameter will be "unknown" for
all edges.
Option RROPDS controls the behaviour of smooth edges in drafting mode. The
calling program should select this option if it is intending to omit smooth
edges which are not coincident with silhouettes (those tagged CODSMO) from the
image. When the option is selected, lines hidden by such edges will be
considered to be obscured by the faces of the smooth edge rather than by the
edge itself, i.e. they will be tagged as CODDRV. If this option is not
selected, then CODSMO lines will obscure other lines in the picture, leading
to apparent errors in the image if the CODSMO lines are not drawn. It is
assumed that smooth edges coincident with silhouettes (those tagged CODSMS)
are always included in the image, hence they will obscure other lines
regardless of whether this option is selected.
Option RROPIN causes the output data for an edge to specify whether or not
the edge is internal to a surface; i.e. the faces on either side of the edge
lie on the same surface. This will be the case if the edge is an internal one
between patches on a B-surface, or is mergeable. The output data
will also specify whether the edge is coincident with a silhouette line
(which is not output), or whether the edge is part of the body silhouette.
The calling program may then choose to omit internal edges from the final
drawing.
If RROPIN is not specified, the internal edge parameter will be "unknown"
for all edges.
Option RROPPC causes the data for a B-Curve (type TYCUPA) to be
output in Bezier form.
Option RROPNC causes the data for a B-Curve (type TYCUPA) to be
output in NURBS format.
The default, if neither RROPPC or RROPNC is supplied, is to output
the data for B-Curves as a poly-line.
Note that at most one of RROPPC and RROPNC may be selected.
Option RROPPS should be specified if a perspective view is required; by
default the system will produce a view from infinity, taking only the
view direction from 'vmatrx'.
Option RROPRG causes regional data to be produced for all visible edges and
silhouettes.
Option RROPRA causes regional data to be produced for all visible edges and
silhouettes adjacent to any face with the regional-data (TYSARG) attribute
attached.
Options RROPPH, RROPRH and RROPPA cause hatch lines to be produced for various
types of face as defined in the documentation for RRVIND.
Option RROPCT controls the representation of curves as polylines. 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.
Bodies are always output hierarchically: for each body to be processed a
hierarchical segment of type body is opened, all the segments in that body
are output, then the hierarchical segment is closed.
If the option RROPHR is specified then edges, silhouettes and hatch-lines of
each body will also be output hierarchically. Hierarchical segments of type
edge, silhouette and hatchline are opened/closed by GOOPSG/GOCLSG
respectively. The non-hierarchical segments enclosed by GOOPSG and GOCLSG
comprise a geometry segment which gives the geometry of the entire
edge/silhouette/hatch-line, and a visibility segment which gives the points
at which the visibility changes and the visibility codes for the
edge/silhouette/hatch-line between these points.
If the option RROPHN is specified then the output will be the same as for
RROPHR but the geometry segment will not be output.
If the option RROPHP is specified then the output will be the same as for
RROPHR but visibility segments will parametrised (i.e. of type SGTPVP) when
the geometry segment is a polyline. See the Downward Interfaces and Functional
Description manuals for more information on parametrised visibility segments.
If the option RROPVP is supplied then the system will attempt only to render
those bodies/faces which are inside or partly inside the viewport supplied.
The viewport is a cuboid region of model space and should be supplied in the
option data as a real list consisting of a centre, three axes, and lengths in
model units along these axes. The axes must be orthogonal but need not be
normalised.
While all faces that are inside or partly inside the viewport will be
rendered, no attempt is made to trim the output to the boundaries of the
viewport, and bodies or faces lying entirely outside, but close to it may be
rendered.
Note that when this option is used with RRHIDL, it is possible to make visible
faces that would not otherwise be so by excluding from the viewport the parts
that would obscure them.
