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Action:
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Creates the silhouettes of the surface.
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Prototype:
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surf_surf_int* bs3_surface_sil (
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bs3_surface,
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// given surface
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logical,
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// TRUE if surface is
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// negated
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view_spec const&,
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// view specification
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SPAbox const&
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// region of interest
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);
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Includes:
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#include "kernel/acis.hxx"
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#include "baseutil/logical.h"
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#include "baseutil/vector/box.hxx"
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#include "kernel/kernint/intsfsf/sfsfint.hxx"
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#include "kernel/spline/bs3_srf/bs3surf.hxx"
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#include "kernel/spline/bs3_srf/sp3srtn.hxx"
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#include "intersct/kernint/makesil/makesil.hxx"
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Description:
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Creates the silhouettes of the surface when viewed from the point or direction specified by the
view_spec (defined in
makesil/makesil.hxx).
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The
view_spec class contains the following information:
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to_point is a position in object space, normally in the general neighborhood of the surface.
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dir is the direction in object space from
to_point to the view position, i.e., opposite to the view direction.
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inv_dist is the reciprocal of the distance from
to_point to the view position, along dir. This is zero for a parallel projection.
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The results of this function are returned using the
surf_surf_int class, but only some of the members are significant:
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cur is a pointer to an
ACIS curve that contains the object-space description of the intersection curve. In most cases this routine will construct an intcurve, but in special cases of parametric surfaces it may return straight lines or ellipses.
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pcur1 is a pointer to parameter-space curves, specifying the curve in the parameter space of the surface.
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start_term,
start_param; If the curve starts at a branch-point (i.e., several silhouettes join there),
start_term points to a
surf_surf_term representing this phenomenon, and
start_param gives its parameter value on this intersection curve. If not,
start_term is
NULL, and
start_param undefined. Note that for a given point, all curve segments starting or ending there must point to the same
surf_surf_term object, not to separate objects with the same position.
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end_term,
end_param; As for
start_term, etc. but for the end of this curve.
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nsplit,
split_param; If this curve has more than one disjoint portion lying within the region of interest, split points must be provided which lie outside the region of interest and divide the curve into portions, each of which has at most one segment within the region of interest. These points are defined by an ordered sequence of parameter values.
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left_surf_rel[0],
right_surf_rel[0]; The visibility of the surface on either side of the curve. If the surface normal on the appropriate side of the curve points away from the view point (i.e., has a positive dot product with the view direction), the relationship is outside, otherwise inside. In this context, left and right are as viewed in the direction of the curve, with the surface normal upwards.
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pcur2,
left_surf_rel[1],
right_surf_rel[1],
int_type,
aux_surf, and
aux_left_rel[ ] are not used.
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Library:
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kernel
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Filename:
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kern/kernel/spline/bs3_srf/sp3srtn.hxx
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Effect:
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Changes model
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