Open CASCADE Technology 6.6.0
Public Member Functions | Protected Attributes
ShapeAnalysis_Surface Class Reference

Complements standard tool Geom_Surface by providing additional
functionality for detection surface singularities, checking
spatial surface closure and computing projections of 3D points
onto a surface.

* The singularities
Each singularity stores the precision with which corresponding
surface iso-line is considered as degenerated.
The number of singularities is determined by specifying precision
and always not greater than 4.

* The spatial closure
The check for spatial closure is performed with given precision
(default value is Precision::Confusion).
If Geom_Surface says that the surface is closed, this class
also says this. Otherwise additional analysis is performed.

* The parameters of 3D point on the surface
The projection of the point is performed with given precision.
This class tries to find a solution taking into account possible
singularities.
Additional method for searching the solution from already built
one is also provided.

This tool is optimised: computes most information only once

#include <ShapeAnalysis_Surface.hxx>

Inheritance diagram for ShapeAnalysis_Surface:
Inheritance graph
[legend]

Public Member Functions

 ShapeAnalysis_Surface (const Handle< Geom_Surface > &S)
 Creates an analyzer object on the basis of existing surface

void Init (const Handle< Geom_Surface > &S)
 Loads existing surface

void Init (const Handle< ShapeAnalysis_Surface > &other)
 Reads all the data from another Surface, without recomputing

void SetDomain (const Standard_Real U1, const Standard_Real U2, const Standard_Real V1, const Standard_Real V2)
const Handle_Geom_Surface & Surface () const
 Returns a surface being analyzed

const Handle_GeomAdaptor_HSurface & Adaptor3d ()
 Returns the Adaptor.
Creates it if not yet done.

const Handle_GeomAdaptor_HSurface & TrueAdaptor3d () const
 Returns the Adaptor (may be Null if method Adaptor() was not called)

Standard_Real Gap () const
 Returns 3D distance found by one of the following methods.
IsDegenerated, DegeneratedValues, ProjectDegenerated
(distance between 3D point and found or last (if not found)
singularity),
IsUClosed, IsVClosed (minimum value of precision to consider
the surface to be closed),
ValueOfUV (distance between 3D point and found solution).

gp_Pnt Value (const Standard_Real u, const Standard_Real v)
 Returns a 3D point specified by parameters in surface
parametrical space

gp_Pnt Value (const gp_Pnt2d &p2d)
 Returns a 3d point specified by a point in surface
parametrical space

Standard_Boolean HasSingularities (const Standard_Real preci)
 Returns True if the surface has singularities for the given
precision (i.e. if there are surface singularities with sizes
not greater than precision).

Standard_Integer NbSingularities (const Standard_Real preci)
 Returns the number of singularities for the given precision
(i.e. number of surface singularities with sizes not greater
than precision).

Standard_Boolean Singularity (const Standard_Integer num, Standard_Real &preci, gp_Pnt &P3d, gp_Pnt2d &firstP2d, gp_Pnt2d &lastP2d, Standard_Real &firstpar, Standard_Real &lastpar, Standard_Boolean &uisodeg)
 Returns the characteristics of the singularity specified by
its rank number <num>.
That means, that it is not neccessary for <num> to be in the
range [1, NbSingularities] but must be not greater than
possible (see ComputeSingularities).
The returned characteristics are:
preci: the smallest precision with which the iso-line is
considered as degenerated,
P3d: 3D point of singularity (middle point of the surface
iso-line),
firstP2d and lastP2d: first and last 2D points of the
iso-line in parametrical surface,
firstpar and lastpar: first and last parameters of the
iso-line in parametrical surface,
uisodeg: if the degenerated iso-line is U-iso (True) or
V-iso (False).
Returns False if <num> is out of range, else returns True.

Standard_Boolean IsDegenerated (const gp_Pnt &P3d, const Standard_Real preci)
 Returns True if there is at least one surface boundary which
is considered as degenerated with <preci> and distance
between P3d and corresponding singular point is less than
<preci>

Standard_Boolean DegeneratedValues (const gp_Pnt &P3d, const Standard_Real preci, gp_Pnt2d &firstP2d, gp_Pnt2d &lastP2d, Standard_Real &firstpar, Standard_Real &lastpar, const Standard_Boolean forward=Standard_True)
 Returns True if there is at least one surface iso-line which
is considered as degenerated with <preci> and distance
between P3d and corresponding singular point is less than
<preci> (like IsDegenerated).
Returns characteristics of the first found boundary matching
those criteria.

Standard_Boolean ProjectDegenerated (const gp_Pnt &P3d, const Standard_Real preci, const gp_Pnt2d &neighbour, gp_Pnt2d &result)
 Projects a point <P3d> on a singularity by computing
one of the coordinates of preliminary computed <result>.

Finds the iso-line which is considered as degenerated with
<preci> and
a. distance between P3d and corresponding singular point is
less than <preci> (like IsDegenerated) or
b. difference between already computed <result>'s coordinate
and iso-coordinate of the boundary is less than 2D
resolution (computed from <preci> by Geom_Adaptor).
Then sets not yet computed <result>'s coordinate taking it
from <neighbour> and returns True.

Standard_Boolean ProjectDegenerated (const Standard_Integer nbrPnt, const TColgp_Array1OfPnt &points, TColgp_Array1OfPnt2d &pnt2d, const Standard_Real preci, const Standard_Boolean direct)
 Checks points at the beginning (direct is True) or end
(direct is False) of array <points> to lie in singularity of
surface, and if yes, adjusts the indeterminate 2d coordinate
of these points by nearest point which is not in singularity.
Returns True if some points were adjusted.

Standard_Boolean IsDegenerated (const gp_Pnt2d &p2d1, const gp_Pnt2d &p2d2, const Standard_Real tol, const Standard_Real ratio)
 Returns True if straight pcurve going from point p2d1 to p2d2
is degenerate, i.e. lies in the singularity of the surface.
NOTE: it uses another method of detecting singularity than
used by ComputeSingularities() et al.!
For that, maximums of distances between points p2d1, p2d2
and 0.5*(p2d1+p2d2) and between corresponding 3d points are
computed.
The pcurve (p2d1, p2d2) is considered as degenerate if:

void Bounds (Standard_Real &ufirst, Standard_Real &ulast, Standard_Real &vfirst, Standard_Real &vlast) const
 Returns the bounds of the surface
(from Bounds from Surface, but buffered)

void ComputeBoundIsos ()
 Computes bound isos (protected against exceptions)

Handle_Geom_Curve UIso (const Standard_Real U)
 Returns a U-Iso. Null if not possible or failed
Remark : bound isos are buffered

Handle_Geom_Curve VIso (const Standard_Real V)
 Returns a V-Iso. Null if not possible or failed
Remark : bound isos are buffered

Standard_Boolean IsUClosed (const Standard_Real preci=-1)
 Tells if the Surface is spatially closed in U with given
precision. If <preci> < 0 then Precision::Confusion is used.
If Geom_Surface says that the surface is U-closed, this method
also says this. Otherwise additional analysis is performed,
comparing given precision with the following distances:

Standard_Boolean IsVClosed (const Standard_Real preci=-1)
 Tells if the Surface is spatially closed in V with given
precision. If <preci> < 0 then Precision::Confusion is used.
If Geom_Surface says that the surface is V-closed, this method
also says this. Otherwise additional analysis is performed,
comparing given precision with the following distances:

gp_Pnt2d ValueOfUV (const gp_Pnt &P3D, const Standard_Real preci)
 Computes the parameters in the surface parametrical space of
3D point.
The result is parameters of the point projected onto the
surface.
This method enhances functionality provided by the standard
tool GeomAPI_ProjectPointOnSurface by treatment of cases when
the projected point is near to the surface boundaries and
when this standard tool fails.

gp_Pnt2d NextValueOfUV (const gp_Pnt2d &p2dPrev, const gp_Pnt &P3D, const Standard_Real preci, const Standard_Real maxpreci=-1.0)
 Projects a point P3D on the surface.
Does the same thing as ValueOfUV but tries to optimize
computations by taking into account previous point <p2dPrev>:
makes a step by UV and tries Newton algorithm.
If <maxpreci> >0. and distance between solution and
P3D is greater than <maxpreci>, that solution is considered
as bad, and ValueOfUV() is used.
If not succeded, calls ValueOfUV()

Standard_Real UVFromIso (const gp_Pnt &P3D, const Standard_Real preci, Standard_Real &U, Standard_Real &V)
 Tries a refinement of an already computed couple (U,V) by
using projecting 3D point on iso-lines:
1. boundaries of the surface,
2. iso-lines passing through (U,V)
3. iteratively received iso-lines passing through new U and
new V (number of iterations is limited by 5 in each
direction)
Returns the best resulting distance between P3D and Value(U,V)
in the case of success. Else, returns a very great value

Standard_Real UCloseVal () const
 Returns minimum value to consider the surface as U-closed

Standard_Real VCloseVal () const
 Returns minimum value to consider the surface as V-closed

const Bnd_BoxGetBoxUF ()
const Bnd_BoxGetBoxUL ()
const Bnd_BoxGetBoxVF ()
const Bnd_BoxGetBoxVL ()

Protected Attributes

Handle_Geom_Surface mySurf
Handle_GeomAdaptor_HSurface myAdSur
Extrema_ExtPS myExtPS
GeomAdaptor_Surface myExtSrf
Standard_Boolean myExtOK
Standard_Integer myNbDeg
Standard_Real myPreci [4]
gp_Pnt myP3d [4]
gp_Pnt2d myFirstP2d [4]
gp_Pnt2d myLastP2d [4]
Standard_Real myFirstPar [4]
Standard_Real myLastPar [4]
Standard_Boolean myUIsoDeg [4]
Standard_Boolean myIsos
Standard_Real myUF
Standard_Real myUL
Standard_Real myVF
Standard_Real myVL
Handle_Geom_Curve myIsoUF
Handle_Geom_Curve myIsoUL
Handle_Geom_Curve myIsoVF
Handle_Geom_Curve myIsoVL
Standard_Boolean myIsoBoxes
Bnd_Box myBndUF
Bnd_Box myBndUL
Bnd_Box myBndVF
Bnd_Box myBndVL
Standard_Real myGap
Standard_Real myUDelt
Standard_Real myVDelt
Standard_Real myUCloseVal
Standard_Real myVCloseVal

Constructor & Destructor Documentation

ShapeAnalysis_Surface::ShapeAnalysis_Surface ( const Handle< Geom_Surface > &  S)

Member Function Documentation

const Handle_GeomAdaptor_HSurface& ShapeAnalysis_Surface::Adaptor3d ( )
void ShapeAnalysis_Surface::Bounds ( Standard_Real ufirst,
Standard_Real ulast,
Standard_Real vfirst,
Standard_Real vlast 
) const
void ShapeAnalysis_Surface::ComputeBoundIsos ( )
Standard_Boolean ShapeAnalysis_Surface::DegeneratedValues ( const gp_Pnt P3d,
const Standard_Real  preci,
gp_Pnt2d firstP2d,
gp_Pnt2d lastP2d,
Standard_Real firstpar,
Standard_Real lastpar,
const Standard_Boolean  forward = Standard_True 
)
Standard_Real ShapeAnalysis_Surface::Gap ( ) const
const Bnd_Box& ShapeAnalysis_Surface::GetBoxUF ( )
const Bnd_Box& ShapeAnalysis_Surface::GetBoxUL ( )
const Bnd_Box& ShapeAnalysis_Surface::GetBoxVF ( )
const Bnd_Box& ShapeAnalysis_Surface::GetBoxVL ( )
Standard_Boolean ShapeAnalysis_Surface::HasSingularities ( const Standard_Real  preci)
void ShapeAnalysis_Surface::Init ( const Handle< Geom_Surface > &  S)
void ShapeAnalysis_Surface::Init ( const Handle< ShapeAnalysis_Surface > &  other)
Standard_Boolean ShapeAnalysis_Surface::IsDegenerated ( const gp_Pnt2d p2d1,
const gp_Pnt2d p2d2,
const Standard_Real  tol,
const Standard_Real  ratio 
)
  • max distance in 3d is less than <tol>
  • max distance in 2d is at least <ratio> times greather than
    the Resolution computed from max distance in 3d
    (max3d < tol && max2d > ratio * Resolution(max3d))
    NOTE: <ratio> should be >1 (e.g. 10)
Standard_Boolean ShapeAnalysis_Surface::IsDegenerated ( const gp_Pnt P3d,
const Standard_Real  preci 
)
Standard_Boolean ShapeAnalysis_Surface::IsUClosed ( const Standard_Real  preci = -1)
  • periodic B-Splines are closed,
  • polinomial B-Spline with boundary multiplicities degree+1
    and Bezier - maximum distance between poles,
  • rational B-Spline or one with boundary multiplicities not
    degree+1 - maximum distance computed at knots and their
    middles,
  • surface of extrusion - distance between ends of basis
    curve,
  • other (RectangularTrimmed and Offset) - maximum distance
    computed at 100 equi-distanted points.
Standard_Boolean ShapeAnalysis_Surface::IsVClosed ( const Standard_Real  preci = -1)
  • periodic B-Splines are closed,
  • polinomial B-Spline with boundary multiplicities degree+1
    and Bezier - maximum distance between poles,
  • rational B-Spline or one with boundary multiplicities not
    degree+1 - maximum distance computed at knots and their
    middles,
  • surface of revolution - distance between ends of basis
    curve,
  • other (RectangularTrimmed and Offset) - maximum distance
    computed at 100 equi-distanted points.
Standard_Integer ShapeAnalysis_Surface::NbSingularities ( const Standard_Real  preci)
gp_Pnt2d ShapeAnalysis_Surface::NextValueOfUV ( const gp_Pnt2d p2dPrev,
const gp_Pnt P3D,
const Standard_Real  preci,
const Standard_Real  maxpreci = -1.0 
)
Standard_Boolean ShapeAnalysis_Surface::ProjectDegenerated ( const Standard_Integer  nbrPnt,
const TColgp_Array1OfPnt points,
TColgp_Array1OfPnt2d pnt2d,
const Standard_Real  preci,
const Standard_Boolean  direct 
)
Standard_Boolean ShapeAnalysis_Surface::ProjectDegenerated ( const gp_Pnt P3d,
const Standard_Real  preci,
const gp_Pnt2d neighbour,
gp_Pnt2d result 
)
void ShapeAnalysis_Surface::SetDomain ( const Standard_Real  U1,
const Standard_Real  U2,
const Standard_Real  V1,
const Standard_Real  V2 
)
Standard_Boolean ShapeAnalysis_Surface::Singularity ( const Standard_Integer  num,
Standard_Real preci,
gp_Pnt P3d,
gp_Pnt2d firstP2d,
gp_Pnt2d lastP2d,
Standard_Real firstpar,
Standard_Real lastpar,
Standard_Boolean uisodeg 
)
const Handle_Geom_Surface& ShapeAnalysis_Surface::Surface ( ) const
const Handle_GeomAdaptor_HSurface& ShapeAnalysis_Surface::TrueAdaptor3d ( ) const
Standard_Real ShapeAnalysis_Surface::UCloseVal ( ) const
Handle_Geom_Curve ShapeAnalysis_Surface::UIso ( const Standard_Real  U)
Standard_Real ShapeAnalysis_Surface::UVFromIso ( const gp_Pnt P3D,
const Standard_Real  preci,
Standard_Real U,
Standard_Real V 
)
gp_Pnt ShapeAnalysis_Surface::Value ( const gp_Pnt2d p2d)
gp_Pnt ShapeAnalysis_Surface::Value ( const Standard_Real  u,
const Standard_Real  v 
)
gp_Pnt2d ShapeAnalysis_Surface::ValueOfUV ( const gp_Pnt P3D,
const Standard_Real  preci 
)
Standard_Real ShapeAnalysis_Surface::VCloseVal ( ) const
Handle_Geom_Curve ShapeAnalysis_Surface::VIso ( const Standard_Real  V)

Field Documentation

Handle_GeomAdaptor_HSurface ShapeAnalysis_Surface::myAdSur [protected]
Handle_Geom_Curve ShapeAnalysis_Surface::myIsoUF [protected]
Handle_Geom_Curve ShapeAnalysis_Surface::myIsoUL [protected]
Handle_Geom_Curve ShapeAnalysis_Surface::myIsoVF [protected]
Handle_Geom_Curve ShapeAnalysis_Surface::myIsoVL [protected]
Handle_Geom_Surface ShapeAnalysis_Surface::mySurf [protected]

The documentation for this class was generated from the following file:
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