occt/dox/user_guides/iges/iges.md

IGES Support

@section occt_iges_1 Introduction

This manual explains how to convert an IGES file to an Open CASCADE Technology (OCCT) shape and vice versa. It provides basic documentation on conversion. For advanced information on conversion, see our offerings on our web site at www.opencascade.org/support/training/

IGES files up to and including IGES version 5.3 can be read. IGES files that are produced by this interface conform to IGES version 5.3 (Initial Graphics Exchange Specification, IGES 5.3. ANS US PRO/IPO-100-1996).

This manual principally deals with two OCCT classes:

• The Reader class, which loads IGES files and translates their contents to OCCT shapes,
• The Writer class, which translates OCCT shapes to IGES entities and then writes these entities to IGES files.

File translation is performed in the programming mode, via C++ calls, and the resulting OCCT objects are shapes.

All definitions in IGES version 5.3 are recognized but only 3D geometric entities are translated. When the processor encounters data, which is not translated, it ignores it and writes a message identifying the types of data, which was not handled. This message can be written either to a log file or to screen output.

@section occt_iges_2 Reading IGES @subsection occt_iges_2_1 Procedure You can translate an IGES file to an OCCT shape by following the steps below: -# Load the file, -# Check file consistency, -# Set the translation parameters, -# Perform the file translation, -# Fetch the results. @subsection occt_iges_2_2 Domain covered @subsubsection occt_iges_2_2_1 Translatable entities The types of IGES entities, which can be translated, are:

• Points
• Lines
• Curves
• Surfaces
• B-Rep entities
• Structure entities (groups). Each entity in the group outputs a shape. There can be a group of groups.
• Subfigures. Each entity defined in a subfigure outputs a shape
• Transformation Matrix.

Note that all non-millimeter length unit values in the IGES file are converted to millimeters.

@subsubsection occt_iges_2_2_2 Attributes Entity attributes in the Directory Entry Section of the IGES file (such as layers, colors and thickness) are translated to Open CASCADE Technology using XDE. @subsubsection occt_iges_2_2_3 Administrative data Administrative data, in the Global Section of the IGES file (such as the file name, the name of the author, the date and time a model was created or last modified) is not translated to Open CASCADE Technology. Administrative data can, however, be consulted in the IGES file.

@subsection occt_iges_2_3 Description of the process @subsubsection occt_iges_2_3_1 Loading the IGES file Before performing any other operation, you have to load the file using the syntax below.

IGESControl_Reader reader; 
IFSelect_ReturnStatus stat  = reader.ReadFile(“filename.igs”); 

The loading operation only loads the IGES file into computer memory; it does not translate it.

@subsubsection occt_iges_2_3_2 Checking the IGES file This step is not obligatory. Check the loaded file with:

Standard_Boolean ok =  reader.Check(Standard_True); 

The variable “ok is True” is returned if no fail message was found; “ok is False” is returned if there was at least one fail message.

reader.PrintCheckLoad  (failsonly, mode); 

Error messages are displayed if there are invalid or incomplete IGES entities, giving you information on the cause of the error.

Standard_Boolean failsonly  = Standard_True or Standard_False; 

If you give True, you will see fail messages only. If you give False, you will see both fail and warning messages.

Your analysis of the file can be either message-oriented or entity-oriented. Choose your preference with IFSelect_PrintCount mode = IFSelect_xxx, where xxx can be any of the following:

• ItemsByEntity gives a sequential list of all messages per IGES entity.
• CountByItem gives the number of IGES entities with their types per message.
• ShortByItem gives the number of IGES entities with their types per message and displays rank numbers of the first five IGES entities per message.
• ListByItem gives the number of IGES entities with their type and rank numbers per message.
• EntitiesByItem gives the number of IGES entities with their types, rank numbers and Directory Entry numbers per message.

@subsubsection occt_iges_2_3_3 Setting translation parameters The following parameters can be used to translate an IGES file to an OCCT shape. If you give a value that is not within the range of possible values, it will be ignored.

read.iges.bspline.continuity

manages the continuity of BSpline curves (IGES entities 106, 112 and 126) after translation to Open CASCADE Technology (Open CASCADE Technology requires that the curves in a model be at least C1 continuous; no such requirement is made by IGES). * 0: no change; the curves are taken as they are in the IGES file. C0 entities of Open CASCADE Technology may be produced. * 1: if an IGES BSpline, Spline or CopiousData curve is C0 continuous, it is broken down into pieces of C1 continuous *Geom_BSplineCurve*. * 2: This option concerns IGES Spline curves only. IGES Spline curves are broken down into pieces of C2 continuity. If C2 cannot be ensured, the Spline curves will be broken down into pieces of C1 continuity.

Read this parameter with:

Standard_Integer ic =  Interface_Static::IVal("read.iges.bspline.continuity"); 

Modify this value with:

if  (!Interface_Static::SetIVal ("read.iges.bspline.continuity",2))  
.. error ..; 

Default value is 1.

This parameter does not change the continuity of curves that are used in the construction of IGES BRep entities. In this case, the parameter does not influence the continuity of the resulting OCCT curves (it is ignored).

read.precision.mode

reads the precision value. * File (0) the precision value is read in the IGES file header (default). * User (1) the precision value is that of the read.precision.val parameter.

Read this parameter with:

Standard_Integer ic =  Interface_Static::IVal("read.precision.mode"); 

Modify this value with:

if  (!Interface_Static::SetIVal ("read.precision.mode",1))  
.. error ..; 

Default value is File (0).

read.precision.val

User defined precision value. This parameter gives the precision for shape construction when the read.precision.mode parameter value is 1. By default it is 0.0001, but can be any real positive (non null) value.

This value is in the measurement unit defined in the IGES file header.

Read this parameter with:

Standard_Real rp =  Interface_Static::RVal("read.precision.val"); 

Modify this parameter with:

if  (!Interface_Static::SetRVal ("read.precision.val",0.001))  
.. error ..; 

Default value is 0.0001.

The value given to this parameter is a target value that is applied to TopoDS_Vertex, TopoDS_Edge and TopoDS_Face entities. The processor does its best to reach it. Under certain circumstances, the value you give may not be attached to all of the entities concerned at the end of processing. IGES-to-OCCT translation does not improve the quality of the geometry in the original IGES file. This means that the value you enter may be impossible to attain the given quality of geometry in the IGES file.

Value of tolerance used for computation is calculated by multiplying the value of read.precision.val and the value of coefficient of transfer from the file units to millimeters.

read.maxprecision.mode

defines the mode of applying the maximum allowed tolerance. Its possible values are:

• Preferred(0) maximum tolerance is used as a limit but sometimes it can be exceeded (currently, only for deviation of a 3D curve of an edge from its pcurves and from vertices of such edge) to ensure shape validity;
• Forced(1) maximum tolerance is used as a rigid limit, i.e. it can not be exceeded and, if this happens, tolerance is trimmed to suit the maximum-allowable value.

Read this parameter with:

Standard_Integer mv =  Interface_Static::IVal("read.maxprecision.mode"); 

Modify this parameter with:

if  (!Interface_Static::SetIVal ("read.maxprecision.mode",1))  
.. error ..; 

Default value is Preferred (0).

read.maxprecision.val

defines the maximum allowable tolerance (in mm) of the shape. It should be not less than the basis value of tolerance set in processor (either Resolution from the file or *read.precision.val*). Actually, the maximum between *read.maxprecision.val* and basis tolerance is used to define maximum allowed tolerance. Read this parameter with: ~~~~~ Standard_Real rp = Interface_Static::RVal("read.maxprecision.val"); ~~~~~ Modify this parameter with: ~~~~~ if (!Interface_Static::SetRVal ("read.maxprecision.val",0.1)) .. error ..; ~~~~~ Default value is 1.

read.stdsameparameter.mode

defines the using of *BRepLib::SameParameter*. Its possible values are: * 0 (Off) - *BRepLib::SameParameter* is not called, * 1 (On) - *BRepLib::SameParameter* is called. *BRepLib::SameParameter* is used through *ShapeFix_Edge::SameParameter*. It ensures that the resulting edge will have the lowest tolerance taking pcurves either unmodified from the IGES file or modified by *BRepLib::SameParameter*. Read this parameter with: ~~~~~ Standard_Integer mv = Interface_Static::IVal("read.stdsameparameter.mode"); ~~~~~ Modify this parameter with: ~~~~~ if (!Interface_Static::SetIVal ("read.stdsameparameter.mode",1)) .. error ..; ~~~~~ Deafault value is 0 (Off).

read.surfacecurve.mode

preference for the computation of curves in case of 2D/3D inconsistency in an entity which has both 2D and 3D representations.

Here we are talking about entity types 141 (Boundary), 142 (CurveOnSurface) and 508 (Loop). These are entities representing a contour lying on a surface, which is translated to a TopoDS_Wire, formed by TopoDS_Edges. Each TopoDS_Edge must have a 3D curve and a 2D curve that reference the surface.

The processor also decides to re-compute either the 3D or the 2D curve even if both curves are translated successfully and seem to be correct, in case there is inconsistency between them. The processor considers that there is inconsistency if any of the following conditions is satisfied:

• the number of sub-curves in the 2D curve is different from the number of sub-curves in the 3D curve. This can be either due to different numbers of sub-curves given in the IGES file or because of splitting of curves during translation.
• 3D or 2D curve is a Circular Arc (entity type 100) starting and ending in the same point (note that this case is incorrect according to the IGES standard).

The parameter read.surfacecurve.mode defines which curve (3D or 2D) is used for re-computing the other one:

• Default(0) use the preference flag value in the entity's Parameter Data section. The flag values are:
  • 0: no preference given,
  • 1: use 2D for 142 entities and 3D for 141 entities,
  • 2: use 3D for 142 entities and 2D for 141 entities,
  • 3: both representations are equally preferred.
• 2DUse_Preferred (2) : the 2D is used to rebuild the 3D in case of their inconsistency,
• 2DUse_Forced (-2): the 2D is always used to rebuild the 3D (even if 2D is present in the file),
• 3DUse_Preferred (3): the 3D is used to rebuild the 2D in case of their inconsistency,
• 3DUse_Forced (-3): the 3D is always used to rebuild the 2D (even if 2D is present in the file),

If no preference is defined (if the value of read.surfacecurve.mode is Default and the value of the preference flag in the entity's Parameter Data section is 0 or 3), an additional analysis is performed.

The 3D representation is preferred to the 2D in two cases:

• if 3D and 2D contours in the file have a different number of curves,
• if the 2D curve is a Circular Arc (entity type 100) starting and ending in the same point and the 3D one is not.

In any other case, the 2D representation is preferred to the 3D.

If either a 3D or a 2D contour is absent in the file or cannot be translated, then it is re-computed from another contour. If the translation of both 2D and 3D contours fails, the whole curve (type 141 or 142) is not translated. If this curve is used for trimming a face, the face will be translated without this trimming and will have natural restrictions.

Read this parameter with:

Standard_Integer ic =  Interface_Static::IVal("read.surfacecurve.mode"); 

Modify this value with:

if  (!Interface_Static::SetIVal ("read.surfacecurve.mode",3))  
.. error ..; 

Default value is Default (0).

read.encoderegularity.angle

This parameter is used within the *BRepLib::EncodeRegularity()* function which is called for a shape read from an IGES or a STEP file at the end of translation process. This function sets the regularity flag of an edge in a shell when this edge is shared by two faces. This flag shows the continuity, which these two faces are connected with at that edge.

Read this parameter with:

Standard_Real era =   Interface_Static::RVal("read.encoderegularity.angle"); 

Modify this parameter with:

if  (!Interface_Static::SetRVal ("read.encoderegularity.angle",0.1))   
.. error ..; 

Default value is 0.01.

read.iges.bspline.approxd1.mode

This parameter is obsolete (it is rarely used in real practice). If set to True, it affects the translation of bspline curves of degree 1 from IGES: these curves (which geometrically are polylines) are split by duplicated points, and the translator attempts to convert each of the obtained parts to a bspline of a higher continuity.

Read this parameter with:

Standard_Real bam =   Interface_Static::CVal("read.iges.bspline.approxd1.mode"); 

Modify this parameter with:

if  (!Interface_Static::SetRVal ("read.encoderegularity.angle","On"))   
.. error ..; 

Default value is Off.

read.iges.resource.name and read.iges.sequence

These two parameters define the name of the resource file and the name of the sequence of operators (defined in that file) for Shape Processing, which is automatically performed by the IGES translator. The Shape Processing is a user-configurable step, which is performed after the translation and consists in application of a set of operators to a resulting shape. This is a very powerful tool allowing to customize the shape and to adapt it to the needs of a receiving application. By default, the sequence consists of a single operator *ShapeFix* that calls Shape Healing from the IGES translator.

Please find an example of the resource file for IGES (which defines parameters corresponding to the sequence applied by default, i.e. if the resource file is not found) in the Open CASCADE Technology installation, by the path %CASROOT%/src/XSTEPResource/IGES .

In order for the IGES translator to use that file, you have to define the environment variable CSF_IGESDefaults, which should point to the directory where the resource file resides. Note that if you change parameter read.iges.resource.name, you should change the name of the resource file and the name of the environment variable correspondingly. The variable should contain a path to the resource file.

Default values:

• read.iges.resource.name - IGES,
• read.iges.sequence - FromIGES.

read.scale.unit

This parameter is obsolete (the parameter *xstep.cascade.unit* should be used instead when necessary). If it is set to 'M', the shape is scaled 0.001 times (as if it were in meters) after translation from IGES or STEP.

Default value is MM.

xstep.cascade.unit

This parameter defines units to which a shape should be converted when translated from IGES or STEP to CASCADE. Normally it is MM; only those applications that work internally in units other than MM should use this parameter.

Default value is MM.

@subsubsection occt_iges_2_3_4 Selecting entities

A list of entities can be formed by invoking the method IGESControl_Reader::GiveList.

Handle(TColStd_HSequenceOfTransient)  list = reader.GiveList(); 

Several predefined operators can be used to select a list of entities of a specific type. To make a selection, you use the method IGESControl_Reader::GiveList with the selection type in quotation marks as an argument. You can also make cumulative selections. For example, you would use the following syntax:

1. Requesting the faces in the file:

faces =  Reader.GiveList("iges-faces"); 

2. Requesting the visible roots in the file:

visibles =  Reader.GiveList(iges-visible-roots); 

3. Requesting the visible faces:

visfac =  Reader.GiveList(iges-visible-roots,faces); 

Using a signature, you can define a selection dynamically, filtering the string by means of a criterion. When you request a selection using the method GiveList, you can give either a predefined selection or a selection by signature. You make your selection by signature using the predefined signature followed by your criterion in parentheses as shown in the example below. The syntaxes given are equivalent to each other.

faces =  Reader.GiveList(“xst-type(SurfaceOfRevolution)”); 
faces =  Reader.GiveList(“iges-type(120)”); 

You can also look for:

• values returned by your signature which match your criterion exactly

faces =  Reader.GiveList(“xst-type(=SurfaceOfRevolution)”); 

• values returned by your signature which do not contain your criterion

faces = Reader.GiveList(“xst-type(!SurfaceOfRevolution)”); 

• values returned by your signature which do not exactly match your criterion.

faces =  Reader.GiveList(“xst-type(!=SurfaceOfRevolution)”); 

List of predefined operators that can be used:

* *xst-model-all* - selects all entities. * *xst-model-roots* - selects all roots. * *xst-transferrable-all* - selects all translatable entities. * *xst-transferrable-roots* - selects all translatable roots (default). * *xst-sharing + selection* - selects all entities sharing at least one entity selected by selection. * *xst-shared + selection* - selects all entities shared by at least one entity selected by selection. * *iges-visible-roots* - selects all visible roots, whether translatable or not. * *iges-visible-transf-roots* - selects all visible and translatable roots. * *iges-blanked-roots* - selects all blank roots, whether translatable or not. * *iges-blanked-transf-roots* - selects all blank and translatable roots. * *iges-status-independant* - selects entities whose IGES Subordinate Status = 0. * *iges-bypass-group* Selects all root entities. If a root entity is a group (402/7 or 402/9), the entities in the group are selected. * *iges-bypass-subfigure* Selects all root entities. If a root entity is a subfigure definition (308), the entities in the subfigure definition are selected. * * iges-bypass-group-subfigure* Selects all root entities. If a root entity is a group (402/7 or 402/9) or a subfigure definition (308), the entities in the group and in the subfigure definition are selected. * *iges-curves-3d* - selects 3D curves, whether they are roots or not (e.g. a 3D curve on a surface). * *iges-basic-geom* - selects 3D curves and untrimmed surfaces. * *iges-faces* - selects face-supporting surfaces (trimmed or not). * *iges-surfaces* - selects surfaces not supporting faces (i.e. with natural bounds). * *iges-basic-curves-3d* selects the same entities as iges-curves-3d. Composite Curves are broken down into their components and the components are selected.

@subsubsection occt_iges_2_3_5 Performing the IGES file translation Perform translation according to what you want to translate:

1. Translate an entity identified by its rank with:

Standard_Boolean ok =  reader.Transfer (rank); 

2. Translate an entity identified by its handle with:

Standard_Boolean ok =  reader.TransferEntity (ent); 

3. Translate a list of entities in one operation with:

Standard_Integer nbtrans =  reader.TransferList (list); 
reader.IsDone(); 

where nbtrans returns the number of items in the list that produced a shape and reader.IsDone() indicates whether at least one entity was translated. 4. Translate a list of entities, entity by entity:

Standard_Integer i,nb =  list-Length();  
for (i = 1; i  = nb; i ++) {  
    Handle(Standard_Transient) ent = list-Value(i);  
    Standard_Boolean OK = reader.TransferEntity (ent);  
} 

5. Translate the whole file (all entities or only visible entities) with:

Standard_Boolean  onlyvisible = Standard_True or Standard_False;  
reader.TransferRoots(onlyvisible) 

@subsubsection occt_iges_2_36 Getting the translation results Each successful translation operation outputs one shape. A series of translations gives a series of shapes.
Each time you invoke TransferEntity, Transfer or Transferlist, their results are accumulated and NbShapes increases. You can clear the results (Clear function) between two translation operations, if you do not do this, the results from the next translation will be added to the accumulation. TransferRoots operations automatically clear all existing results before they start.

Standard_Integer nbs =  reader.NbShapes(); 

returns the number of shapes recorded in the result.

TopoDS_Shape shape =  reader.Shape(num);, 

returns the result num, where num is an integer between 1 and NbShapes.

TopoDS_Shape shape =  reader.Shape(); 

returns the first result in a translation operation.

TopoDS_Shape shape =  reader.OneShape(); 

returns all results in a single shape which is:

• a null shape if there are no results,
• in case of a single result, a shape that is specific to that result,
• a compound that lists the results if there are several results.

reader.Clear(); 

erases the existing results.

reader.PrintTransferInfo  (failsonly, mode); 

displays the messages that appeared during the last invocation of Transfer or TransferRoots.

If failsonly is IFSelect_FailOnly, only fail messages will be output, if it is IFSelect_FailAndWarn, all messages will be output. Parameter “mode” can have IFSelect_xxx values where xxx can be:

• GeneralCount - gives general statistics on the transfer (number of translated IGES entities, number of fails and warnings, etc)
• CountByItem - gives the number of IGES entities with their types per message.
• ListByItem - gives the number of IGES entities with their type and DE numbers per message.
• ResultCount - gives the number of resulting OCCT shapes per type.
• Mapping gives mapping between roots of the IGES file and the resulting OCCT shape per IGES and OCCT type.

@subsection occt_iges_2_4 Mapping of IGES entities to Open CASCADE Technology shapes

NOTE that IGES entity types that are not given in the following tables are not translatable.

@subsubsection occt_iges_2_4_1 Points

| IGES entity type | CASCADE shape | Comments |

| ----------------: | -------------: | ---------: |

| 116: Point | TopoDS_Vertex |

@subsubsection occt_iges_2_4_2 Curves Curves, which form the 2D of face boundaries, are translated as Geom2D_Curves (Geom2D circles, etc.).

IGES entity type CASCADE shape Comments 100: Circular Arc TopoDS_Edge The geometrical support is:

• a Geom_Circle,
• or a Geom_TrimmedCurve. A Geom_TrimmedCurve is output if the arc is not closed. 102: Composite Curve TopoDS_Wire The resulting shape is always a TopoDS_Wire that is built from a set of TopoDS_Edges. Each TopoDS_Edge is connected to the preceding and to the following edge by a common TopoDS_Vertex. 104: Conic Arc TopoDS_Edge The geometric support depends on whether the IGES entity's form is:
• 0 (Geom_Circle),
• 1 (Geom_Ellipse),
• 2 (Geom_Hyperbola),
• or 3 (Geom_Parabola). A Geom_TrimmedCurve is output if the arc is not closed. 106: Copious Data TopoDS_Edge or TopoDS_Wire IGES entity Copious Data (type 106, forms 1-3) is translated just as the IGES entities Linear Path (106/11-13) and the Simple Closed Planar Curve (106/63). Vectors applying to forms other than 11,12 or 63 are ignored. The Geom_BSplineCurve (geometrical support) has C0 continuity. If the Copious Data has vectors (DataType = 3) they will be ignored. 110: Line TopoDS_Edge The supporting curve is a Geom_TrimmedCurve whose basis curve is a Geom_Line. 112: Parametric Spline Curve TopoDS_Edge or TopoDS_Wire The geometric support is a Geom_BsplineCurve. 126: BSpline Curve TopoDS_Edge or TopoDS_Wire 130: Offset Curve TopoDS_Edge or TopoDS_Wire The resulting shape is a TopoDS_Edge or a TopoDS_Wire (depending on the translation of the basis curve) whose geometrical support is a Geom_OffsetCurve built from a basis Geom_Curve. Limitation: The IGES Offset Type value must be 1. 141: Boundary TopoDS_Wire Same behavior as for the Curve On Surface (see below). The translation of a non-referenced Boundary IGES entity in a BoundedSurface IGES entity outputs a TopoDS_Edge or a TopoDS_Wire with a Geom_Curve. 142: Curve On Surface TopoDS_Wire Each TopoDS_Edge is defined by a 3D curve and by a 2D curve that references the surface.

The type of OCCT shapes (either TopDS_Edges or TopoDS_Wires) that result from the translation of IGES entities 106, 112 and 126 depends on the continuity of the curve in the IGES file and the value of the read.iges.bspline.continuity translation parameter.

@subsubsection occt_iges_2_4_3 Surfaces Translation of a surface outputs either a TopoDS_Face or a TopoDS_Shell.
If a TopoDS_Face is output, its geometrical support is a Geom_Surface and its outer and inner boundaries (if it has any) are TopoDS_Wires.

IGES entity type CASCADE shape Comments 108: Plane TopoDS_Face The geometrical support for the TopoDS_Face is a Geom_Plane and the orientation of its TopoDS_Wire depends on whether it is an outer TopoDS_Wire or whether it is a hole. 114: Parametric Spline Surface TopoDS_Face The geometrical support of a TopoDS_Face is a Geom_BSplineSurface. 118: Ruled Surface TopoDS_Face or TopoDS_Shell The translation of a Ruled Surface outputs:

• a TopoDS_Face if the profile curves become TopoDS_Edges,
• a TopoDS_Shell if the profile curves become TopoDS_Wires.

Limitation: This translation cannot be completed when these two TopoDS_Wires are oriented in different directions. 120: Surface Of Revolution TopoDS_Face or TopoDS_Shell The translation of a Surface Of Revolution outputs:

• a TopoDS_Face if the generatrix becomes a TopoDS_Edge,
• a TopoDS_Shell if the generatrix becomes a TopoDS_Wire. The geometrical support may be: - a Geom_CylindricalSurface, - a Geom_ConicalSurface, - a Geom_SphericalSurface, - a Geom_ToroidalSurface - or a Geom_SurfaceOfRevolution depending on the result of the CASCADE computation (based on the generatrix type). 122: Tabulated Cylinder TopoDS_Face or TopoDS_Shell The translation outputs:
• a TopoDS_Face if the base becomes a TopoDS_Edge,
• a TopoDS_Shell if the base becomes a TopoDS_Wire.

The geometrical support may be:

• a Geom_Plane,

• a Geom_Cylindrical Surface,

• a Geom_SurfaceOfLinearExtrusion depending on the result of the CASCADE computation (based on the generatrix type). The Geom_Surface geometrical support is limited according to the generatrix. 128: BSpline Surface TopoDS_Face The geometrical support of the TopoDS_Face is a Geom_BsplineSurface. 140: Offset Surface TopoDS_Face

  The translation of an Offset Surface outputs a TopoDS_Face whose geometrical support is a Geom_OffsetSurface.

Limitations: For OCCT algorithms, the original surface must be C1-continuous so that the Geom_OffsetSurface can be created. If the basis surface is not C1-continuous, its translation outputs a TopoDS_Shell and only the first TopoDS_Face in the TopoDS_Shell is offset. 143: Bounded Surface TopoDS_Face or TopoDS_Shell If the basis surface outputs a TopoDS_Shell (that has more than one TopoDS_Face), the IGES boundaries are not translated.

Limitations: If the bounding curves define holes, natural bounds are not created. If the orientation of the contours is wrong, it is not corrected. 144: Trimmed Surface TopoDS_Face or TopoDS_Shell For the needs of interface processing, the basis surface must be a face. Shells are only processed if they are single-face. The contours (wires that are correctly oriented according to the definition of the IGES 142: Curve On Surface entity) are added to the face that is already created. If the orientation of the contours is wrong, it is corrected. 190: Plane Surface TopoDS_Face This type of IGES entity can only be used in BRep entities in place of an IGES 108 type entity. The geometrical support of the face is a Geom_Plane.

@subsubsection occt_iges_2_4_4 Boundary Representation Solid Entities

IGES entity type CASCADE shape Comments 186: ManifoldSolid TopoDS_Solid 514: Shell TopoDS_Shell 510: Face TopoDS_Face This is the lowest IGES entity in the BRep structure that can be specified as a starting point for translation. 508: Loop TopoDS_Wire 504: Edge List 502: Vertex List

@subsubsection occt_iges_2_4_5 Structure Entities

IGES entity type CASCADE shape Comments 402/1: Associativity Instance: Group with back pointers TopoDS_Compound 402/7: Associativity Instance: Group without back pointers TopoDS_Compound 402/9: Associativity Instance: Single Parent TopoDS_Face The translation of a SingleParent entity is only performed for 402 form 9 with entities 108/1 and 108/-1. The geometrical support for the TopoDS_Face is a Geom_Plane with boundaries:

• the parent plane defines the outer boundary,
• child planes define the inner boundaries.

@subsubsection occt_iges_2_4_6 Subfigures

IGES entity type CASCADE shape Comments 308: Subfigure Definition TopoDS_Compound This IGES entity is only translated when there are no Singular Subfigure Instance entities. 408: Singular Subfigure Instance TopoDS_Compound This shape has the Subfigure Definition Compound as its origin and is positioned in space by its translation vector and its scale factor.

@subsubsection occt_iges_2_4_7 Transformation Matrix

IGES entity type CASCADE shape Comments 124: Transformation Matrix Geom_Transformation This entity is never translated alone. It must be included in the definition of another entity.

@subsection occt_iges_2_5 Messages Messages are displayed concerning the normal functioning of the processor (transfer, loading, etc.).
You must declare an include file:

#includeInterface_DT.hxx 

You have the choice of the following options for messages:

IDT_SetLevel (level); 

level modifies the level of messages:

• 0: no messages
• 1: raise and fail messages are displayed, as are messages concerning file access,
• 2: warnings are also displayed.

IDT_SetFile (“tracefile.log”); 

prints the messages in a file,

IDT_SetStandard(); 

restores screen output.

@subsection occt_iges_2_6 Tolerance management @subsubsection occt_iges_2_6_1 Values used for tolerances during reading IGES

During the transfer of IGES to Open CASCADE Technology several parameters are used as tolerances and precisions for different algorithms. Some of them are computed from other using specific functions.

3D (spatial) tolerances

• Package method Precision::Confusion equal to 10^-7 is used as a minimal distance between points, which are considered distinct.
• Resolution in the IGES file is defined in the Global section of an IGES file. It is used as a fundamental value of precision during the transfer.
• User-defined variable read.precision.val can be used instead of resolution from the file when parameter read.precision.mode is set to 1 ("User").
• Field EpsGeom of the class IGESToBRep_CurveAndSurface is a basic precision for translating an IGES object. It is set for each object of class IGESToBRep_CurveAndSurface and its derived classes. It is initialized for the root of transfer either by value of resolution from the file or by value of read.precision.val, depending on the value of read.precision.mode parameter. It is returned by call to method IGESToBRep_CurvAndSurface::GetEpsGeom. As this value belongs to measurement units of the IGES file, it is usually multiplied by the coefficient UnitFactor (returned by method IGESToBRep_CurvAndSurface::GetUnitFactor) to convert it to Open CASCADE Technology units.
• Field MaxTol of the class IGESToBRep_CurveAndSurface is used as the maximum tolerance for some algorithms. Currently, it is computed as the maximum between 1 and GetEpsGeom*GetUnitFactor. This field is returned by method IGESToBRep_CurvAndSurface::GetMaxTol.

2D (parametric) tolerances

• Package method Precision::PConfusion equal to 0.01*Precision::Confusion, i.e. 10^-9. It is used to compare parametric bounds of curves.
• Field EpsCoeff of the class IGESToBRep_CurveAndSurface is a parametric precision for translating an IGES object. It is set for each object of class IGESToBRep_CurveAndSurface and its derived classes. Currently, it always has its default value 10^-6. It is returned by call to method IGESToBRep_CurvAndSurface::GetEpsCoeff. This value is used for translating 2d objects (for instance, parametric curves).
• Methods UResolution(tolerance3d) and VResolution(tolerance3d) of the class GeomAdaptor_Surface or BRepAdaptor_Surface return tolerance in parametric space of a surface computed from 3D tolerance. When one tolerance value is to be used for both U and V parametric directions, the maximum or the minimum value of UResolution and VResolution is used.
• Methods Resolution(tolerance3d) of the class GeomAdaptor_Curve or BRepAdaptor_Curve return tolerance in the parametric space of a curve computed from 3d tolerance.

Zero-dimensional tolerances

* Field *Epsilon* of the class *IGESToBRep_CurveAndSurface* is set for each object of class *IGESToBRep_CurveAndSurface* and returned by call to method *GetEpsilon*. It is used in comparing angles and converting transformation matrices. In most cases, it is reset to a fixed value (10^-5 - 10^-3) right before use. The default value is 10^-4.

@subsubsection occt_iges_2_6_2 Initial setting of tolerances in translating objects

Transfer starts from one entity treated as a root (either the actual root in the IGES file or an entity selected by the user). The function which performs the transfer (that is IGESToBRep_Actor::Transfer or IGESToBRep_Reader::Transfer) creates an object of the type IGESToBRep_CurveAndSurface, which is intended for translating geometry.

This object contains three tolerances: Epsilon, EpsGeom and EpsCoeff.

Parameter Epsilon is set by default to value 10^-4. In most cases when it is used in the package IGESToBRep, it is reset to a fixed value, either 10^-5 or 10^-4 or 10^-3. It is used as precision when comparing angles and transformation matrices and does not have influence on the tolerance of the resulting shape.

Parameter EpsGeom is set right after creating a IGESToBRep_CurveAndSurface object to the value of resolution, taken either from the Global section of an IGES file, or from the XSTEP.readprecision.val parameter, depending on the value of XSTEP.readprecision.mode.

Parameter EpsCoeff is set by default to 10^-6 and is not changed.

During the transfer of a shape, new objects of type IGESToBRep_CurveAndSurface are created for translating subshapes. All of them have the same tolerances as the root object.

@subsubsection occt_iges_2_6_3 Transfer process

Translating into Geometry

Geometrical entities are translated by classes *IGESToBRep_BasicCurve* and *IGESToBRep_BasicSurface*. Methods of these classes convert curves and surfaces of an IGES file to Open CASCADE Technology geometry objects: *Geom_Curve, Geom_Surface,* and *Geom_Transformation*.

Since these objects are not BRep objects, they do not have tolerances. Hence, tolerance parameters are used in these classes only as precisions: to detect specific cases (e.g., to distinguish a circle, an ellipse, a parabola and a hyperbola) and to detect bad cases (such as coincident points).

Use of precision parameters is reflected in the following classes:

• IGESToBRep_BasicCurve - all parameters and points are compared with precision EpsGeom. All transformations (except IGESToBRep_BasicCurve::TransferTransformation) are fulfilled with precision Epsilon which is set to 10^-3 (in the IGESToBRep_BasicCurve::TransferTransformation the value 10^-5 is used).
• IGESToBRep_BasicCurve::TransferBSplineCurve - all weights of BSplineCurve are assumed to be more than Precision::PConfusion (else the curve is not translated).
• IGESToBRep_BasicSurface all parameters and points are compared with precision EpsGeom. All transformations are fulfilled with precision Epsilon, which is set to 10^-3.
• IGESToBRep_BasicSurface::TransferBSplineSurface - all weights of BSplineSurface are assumed to be more than Precision::PConfusion (else the surface is not translated).

Translating into Topology

IGES entities represented as topological shapes and geometrical objects are translated into OCCT shapes by use of the following classes: IGESToBRep_TopoCurve, IGESToBRep_TopoSurface, IGESToBRep_BRepEntity, ShapeFix_Wire Class IGESToBRep_BRepEntity is intended for transferring BRep entities (IGES version ³ 5.1) while the two former are used for translating geometry and topology defined in IGES 5.1. Methods from IGESToBRep_BRepEntity call methods from IGESToBRep_TopoCurve and IGESToBRep_TopoSurface, while those call methods from IGESToBRep_BasicCurve and IGESToBRep_BasicSurface in order to translate IGES geometry into OCCT geometry. Although the IGES file contains only one parameter for tolerance in the Global Section, OCCT shapes are produced with different tolerances. As a rule, updating the tolerance is fulfilled according to local distances between shapes (distance between vertices of adjacent edges, deviation of edge’s 3D curve and its parametric curve and so on) and may be less or greater than precision in the file. The following classes show what default tolerances are used when creating shapes and how they are updated during transfer.

Class IGESToBRep_TopoCurve

All the methods which are in charge of transferring curves from IGES curve entities (TransferCompositeCurve, Transfer2dCompositeCurve, TransferCurveOnFace, TransferBoundaryOnFace, TransferOffsetCurve, TransferTopoBasicCurve) if an entity has transformation call to IGESData_ToolLocation::ConvertLocation with Epsilon value set to 10-4. * IGESToBRep_TopoCurve::TransferPoint Vertex is constructed from a Point entity with tolerance EpsGeom*UnitFactor. * IGESToBRep_TopoCurve::Transfer2dPoint Vertex is constructed from a Point entity with tolerance EpsCoeff. * IGESToBRep_TopoCurve::TransferCompositeCurveGeneral Obtains shapes (edges or wires) from other methods and adds them into the resulting wire. Two adjacent edges of the wire can be connected with tolerance up to MaxTol. * IGESToBRep_TopoCurve::TransferCurveOnFace and IGESToBRep_TopoCurve::TransferBoundaryOnFace This method builds a wire from 3D and 2D representations of a curve on surface. Edges and vertices of the wire cannot have tolerance larger than MaxTol. The value EpsGeom*UnitFactor is passed into ShapeFix_Wire::SetPrecision and MaxTol - into ShapeFix_Wire::MaxTolerance. To find out how these parameters affect the resulting tolerance changes, please refer to class ShapeFix_Wire. * IGESToBRep_TopoCurve::TransferTopoBasicCurve and IGESToBRep_TopoCurve::Transfer2dTopoBasicCurve The boundary vertices of an edge (or a wire if a curve was of C0 continuity) translated from a basis IGES curve (BSplineCurve, CopiousData, Line, etc.) are built with tolerance EpsGeom*UnitFactor, the tolerance of the edge(s) is (are) Precision::Confusion*.* If a curve was divided into several edges, the common vertices of such adjacent edges have tolerance Precision::Confusion*.*

Class IGESToBRep_TopoSurface

All the faces created by this class have tolerance Precision::Confusion*.*

Class IGESToBRep_BRepEntity

* IGESToBRep_BRepEntity::TransferVertex The vertices from the VertexList entity are constructed with tolerance EpsGeom*UnitFactor. * IGESToBRep_BRepEntity::TransferEdge The edges from the EdgeList entity are constructed with tolerance Precision::Confusion*.* * IGESToBRep_BRepEntity::TransferLoop This function works like IGESToBRep_TopoCurve::TransferCurveOnFace* *and* *IGESToBRep_TopoCurve::TransferBoundaryOnFace*.* * IGESToBRep_BRepEntity::TransferFace The face from the Face IGES entity is constructed with tolerance Precision::Confusion.

Shape Healing classes

After performing a simple mapping, shape-healing algorithms are called (class ShapeFix_Shape) by IGESToBRep_Actor::Transfer(). A shape-healing algorithm performs the correction of a resulting OCCT shape. Class ShapeFix_Wire can increase the tolerance of a shape. This class is used in IGESToBRep_BRepEntity::TransferLoop*,* IGESToBRep_TopoCurve::TransferBoundaryOnFace and IGESToBRep_TopoCurve::TransferCurveOnFace for correcting a wire. The maximum possible tolerance which edges or vertices will have after invoking the methods of this class is MaxTolerance (set by method ShapeFix_Wire::MaxTolerance()).

@subsection occt_iges_2_7 Code architecture @subsubsection occt_iges_2_71 List of the classes

Package IGESControl

IGESControl_Reader

Package IGESToBRep

IGESToBRep_Reader IGESToBRep_Actor IGESToBRep_CurveAndSurface IGESToBRep_BasicCurve IGESToBRep_BasicSurface IGESToBRep_TopoCurve IGESToBRep_TopoSurface IGESToBRep_BRepEntity

Package IGESConvGeom

For description of classes, refer to CDL. @subsubsection occt_iges_2_72 List of API classes

package IGESControl

IGESControl_Reader

package IGESToBRep

IGESToBRep_Reader

package IGESData

class IGESData_IGESModel class IGESData_IGESEntity For details, refer to 4 API for reading/writing IGES and CDL. @subsubsection occt_iges_2_73 Graph of calls The following diagram illustrates the structure of calls in reading IGES. The highlighted classes produce OCCT geometry. @image html /user_guides/iges/images/iges_image003.jpg @image latex /user_guides/iges/images/iges_image003.jpg

@subsection occt_iges_2_8 Example #include “IGESControl_Reader.hxx” #include “TColStd_HSequenceOfTransient.hxx” #include “TopoDS_Shape.hxx” { IGESControl_Reader myIgesReader; Standard_Integer nIgesFaces,nTransFaces;

myIgesReader.ReadFile (“MyFile.igs”); //loads file MyFile.igs

Handle(TColStd_HSequenceOfTransient) myList = myIgesReader.GiveList(“iges-faces”); //selects all IGES faces in the file and puts them into a list called //MyList,

nIgesFaces = myList-Length();
nTransFaces = myIgesReader.TransferList(myList); //translates MyList,

cout“IGES Faces: “nIgesFaces“ Transferred:”nTransFacesendl; TopoDS_Shape sh = myIgesReader.OneShape(); //and obtains the results in an OCCT shape. }

@section occt_1856844696_874243683 Writing IGES @subsection occt_1856844696_8742436831 Procedure You can translate OCCT shapes to IGES entities in the following steps: 1.       initialize the process. 2.       set the translation parameters, 3.       perform the model translation, 4.       write the output IGES file. You can translate several shapes before writing a file. Each shape will be a root entity in the IGES model. @subsection occt_1856844696_8742436832 Domain covered There are two families of OCCT objects that can be translated:

• geometrical,
• topological. @subsection occt_1856844696_8742436833 Description of the process @subsubsection occt_1856844696_87424368331 Initializing the process Choose the unit and the mode you want to use to write the output file as follows: IGESControl_Controller::Init performs standard initialization. Returns False if an error occurred. IGESControl_Writer writer;
  uses the default unit (millimeters) and the default write mode (Face). IGESControl_Writer writer (UNIT);
  uses the Face write mode and any of the units that are accepted by IGES.
  IGESControl_Writer writer (UNIT,modecr);
  uses the unit (accepted by IGES) and the write mode of your choice.
• 0: Faces,
• 1: BRep The result is an IGESControl_Writer object. @subsubsection occt_1856844696_87424368332 Setting the translation parameters The following parameters are used for the OCCT-to-IGES translation.

write.iges.brep.mode:

gives the choice of the write mode. You can choose the following write modes:

;Faces; (0): OCCT TopoDS_Faces will be translated into IGES 144 (Trimmed Surface) entities, no B-Rep entities will be written to the IGES file,
;BRep; (1): OCCT TopoDS_Faces will be translated into IGES 510 (Face) entities, the IGES file will contain B-Rep entities.
Read this parameter with:
Standard_Integer byvalue = Interface_Static::IVal(;write.iges.brep.mode;); Modify this parameter with:
Interface_Static::SetIVal (;write.iges.brep.mode;, 1); Default value is ;Faces; (0).

write.convertsurface.mode

For writing to IGES in the BRep mode (see parameter write.iges.brep.mode), this parameter indicates whether elementary surfaces (cylindrical, conical, spherical, and toroidal) are converted into corresponding IGES 5.3 entities (if parameter's value is On), or written as surfaces of revolution (by default). Default value is Off.

write.iges.unit:

gives the choice of the unit. The default unit for Open CASCADE Technology is the millimeter. You can choose to write your file in any of the units that are accepted by IGES. Read this parameter with: Standard_String byvalue = Interface_Static::CVal(;write.iges.unit;); Modify this parameter with: Interface_Static::SetCVal (;write.iges.unit;, ;INCH;); Default value is ;MM;.

write.iges.header.autor:

gives the name of the author of the file. Read this parameter with: Standard_String byvalue = Interface_Static::CVal(;write.iges.header.author;); Modify this value with: Interface_Static::SetCVal (;write.iges.header.author;, ;name;); Default value is the system name of the user.

write.iges.header.company:

gives the name of the sending company. Read this parameter with: Standard_String byvalue = Interface_Static::CVal(;write.iges.header.company;); Modify this value with: Interface_Static::SetCVal (;write.iges.header.company;, ;MDTV;); Default value is ;; (empty).

write.iges.header.product:

gives the name of the sending product. Read this parameter with: Standard_String byvalue = Interface_Static::CVal(;write.iges.header.product;); Modify this value with: Interface_Static::SetCVal (;write.iges.header.product;, ;product name;); Default value is ;CAS.CADE IGES processor Vx.x; where x.x means the current version of Open CASCADE Technology.

write.iges.header.receiver:

gives the name of the receiving company. Read this parameter with: Standard_String byvalue = Interface_Static::CVal(;write.iges.header.receiver;); Modify this value with: Interface_Static::SetCVal (;write.iges.header.receiver;, ;reciever name;); Default value is ;; (empty).

write.precision.mode:

specifies the mode of writing the resolution value into the IGES file. ;Least; (-1): resolution value is set to the minimum tolerance of all edges and all vertices in an OCCT shape, ;Average; (0): resolution value is set to average between the average tolerance of all edges and the average tolerance of all vertices in an OCCT shape (default), ;Greatest; (1): resolution value is set to the maximum tolerance of all edges and all vertices in an OCCT shape, ;Session; (2): resolution value is that of the write.precision.val parameter. Read this parameter with: Standard_Integer ic = Interface_Static::IVal(;write.precision.mode;); Modify this parameter with: if (!Interface_Static::SetIVal(;write.precision.mode;,1)) .. error .. Default value is ;Average; (0).

write.precision.val:

user precision value. This parameter gives the resolution value for an IGES file when the write.precision.mode parameter value is 1. 0.0001: default any real positive (non null) value. Read this parameter with: Standard_Real rp = Interface_Static::RVal(;write.precision.val;); Modify this parameter with: if (!Interface_Static::SetRVal(;write.precision.val;,0.01)) .. error .. Default value is 0.0001.

write.iges.resource.name

write.iges.sequence

The same as read.iges.*, please see above. Note that the default sequence for writing contains one operator – DirectFaces - which converts elementary surfaces based on left-hand axes (valid in CASCADE) to right-hand axes (which are valid only in IGES). Default values : write.iges.resource.name – IGES, write.iges.sequence – ToIGES. @subsubsection occt_1856844696_87424368333 Performing the Open CASCADE Technology shape translation You can perform the translation in one or several operations. Here is how you translate topological and geometrical objects: Standard_Boolean ok = writer.AddShape (shape); where shape is a TopoDS_Shape. ok is True if translation was correctly performed and False if there was at least one entity that was not translated. Standard_Boolean ok = writer.AddGeom (geom); where geom is either Handle(Geom_Curve) or Handle(Geom_Surface) ok is True if the translation was correctly performed and False if there was at least one entity whose geometry was not among the allowed types. @subsubsection occt_1856844696_87424368334 Writing the IGES file Write the IGES file with: Standard_Boolean ok = writer.Write (;filename.igs;); to give the file name. Standard_Boolean ok = writer.Write (S); where S is Standard_OStream ok is True if the operation was correctly performed and False if an error occurred (for instance, if the processor could not create the file). @subsection occt_1856844696_8742436834 Mapping Open CASCADE Technology shapes to IGES entities Translated objects depend on the write mode that you chose. If you chose the Face mode, all of the shapes are translated, but the level of topological entities becomes lower (geometrical one). If you chose the BRep mode, topological OCCT shapes become topological IGES entities. @subsubsection occt_1856844696_87424368341 Curves @subsubsection occt_1856844696_87424368342 Surfaces

@subsubsection occt_1856844696_87424368343 Topological entities

Translation in Face mode

Translation in BRep mode

@subsection occt_1856844696_8742436835 Tolerance management @subsubsection occt_1856844696_87424368351 Setting resolution in an IGES file There are several possibilities to set resolution in an IGES file. They are controlled by write.precision.mode parameter; the dependence between the value of this parameter and the set resolution is described in paragraph 3.3.2 Setting the translation parameters. If the value of parameter write.precision.mode is -1, 0 or 1, resolution is computed from tolerances of sub-shapes inside the shape to be translated. In this computation, only tolerances of TopoDS_Edges and TopoDS_Vertices participate since they reflect the accuracy of the shape. TopoDS_Faces are ignored in computations since their tolerances may have influence on resulting computed resolution while IGES resolution mainly concerns points and curves but not surfaces.

@subsection occt_1856844696_8742436836 Code architecture @subsubsection occt_1856844696_87424368361 List of the classes

package IGESControl

IGESControl_Controller IGESControl_Writer

package BRepToIGES

BRepToIGES_BREntity BRepToIGES_BRWire BRepToIGES_BRShell BRepToIGES_BRSolid

package BRepToIGESBRep

BRepToIGESBRep_Entity

package GeomToIGES

GeomToIGES_GeomPoint GeomToIGES_GeomVector GeomToIGES_GeomCurve GeomToIGES_GeomSurface

package Geom2dToIGES

Geom2dToIGES_Geom2dCurve

package IGESConvGeom

IGESConvGeom_GeomBuilder For description of classes refer to CDL. @subsubsection occt_1856844696_87424368362 List of API classes

package IGESControl

* IGESControl_Controller * IGESControl_Writer

package IGESData

* class IGESData_IGESModel * class IGESData_IGESEntity For details refer to 4. API for reading/writing IGES and CDL. @subsubsection occt_1856844696_87424368363 Graph of calls The following diagram illustrates the class structure in writing IGES. The highlighted classes are intended to translate geometry.

	@image html /user_guides/iges/images/iges_image004.jpg
@image latex /user_guides/iges/images/iges_image004.jpg

@subsection occt_1856844696_8742436837 Example #include IGESControl_Controller.hxx #include IGESControl_Writer.hxx #include TopoDS_Shape.hxx Standard_Integer main() { IGESControl_Controller::Init(); IGESControl_Writer ICW (;MM;, 0); //creates a writer object for writing in Face mode with millimeters TopoDS_Shape sh; ICW.AddShape (sh); //adds shape sh to IGES model ICW.ComputeModel(); Standard_Boolean OK = ICW.Write (;MyFile.igs;); //writes a model to the file MyFile.igs } @section occt_1856844696_1288309531 API for reading/writing IGES @subsection occt_1856844696_12883095311 Overview API classes provides the following tools:

• loading IGES files into memory,
• checking IGES files consistency,
• translating IGES files into OCCT shapes,
• translating OCCT shapes into IGES files,
• accessing the IGES model (which is an image of the IGES file in memory),
• selecting entities from the IGES model,
• accessing each entity in the IGES model. @subsection occt_1856844696_12883095312 Package IGESControl @subsubsection occt_1856844696_128830953121 General description This package is intended to provide a tool to convert IGES-format entities to OCCT shapes and vice versa. The package allows the end-user to perform both import from and export to an IGES file. IGES files up to and including IGES version 5.3 can be read. IGES files that are produced by this component conform to IGES version 5.3. The result of reading IGES files is either a single Open CASCADE Technology shape or a set of them, the result of exporting Open CASCADE Technology geometric or topologic objects is an IGES file which may include one or several root entities (the ones not referenced by others). @subsubsection occt_1856844696_128830953122 Class IGESControl_Controller

General description

This class controls the IGES norm. This class is intended to provide an appropriate initialization of the IGES norm, namely it includes a set of necessary parameters for IGES translation and declaration of possible selections for IGES entities. After the execution of initialization procedures, the use of IGES norm becomes available. Inheritance Standard_Transient MMgt_TShared XSControl_Controller

Methods

Constructors

IGESControl_Controller(const Standard_Boolean modefnes = Standard_False); Purpose: Initializes the use of IGES (if modefnes is False) or FNES (if modefnes is True) norm.

Method for performing initialization

IGESControl:: Init static Standard_Boolean Init() ; Purpose: Performs standard initialization creating controller objects for both IGES and FNES norm. Returns True when done, False if an error occurred.

Method for creating IGES model

IGESControl:: NewModel Handle_Interface_InterfaceModel NewModel() const; Purpose: Creates a new empty model ready to receive data of the norm. The Global section is filled with static parameters (receiver, author, company and unit).

Method for getting the actor object

IGESControl:: ActorRead Handle_Transfer_ActorOfTransientProcess ActorRead( const Handle(Interface_InterfaceModel)& model) const; Purpose: Returns the actor object for reading (actually, it is of type IGESToBRep_Actor) with a set parameter of spline continuity taken from static parameter.

Method for translating an Open CASCADE Technology shape

IGESControl:: TransferWriteShape virtual IFSelect_ReturnStatus TransferWriteShape(const TopoDS_Shape& shape, const Handle(Transfer_FinderProcess)& FP, const Handle(Interface_InterfaceModel)& model, const Standard_Integer modetrans = 0) const; Purpose: Translates shape into the interface model. modetrans: 0 - group of Faces (IGES 5.1) , 1 - for BRep (IGES = 5.1) Returns: IFSelect_RetDone: OK, IFSelect_RetError: if modetrans is not equal to 0 or 1, or model is not an IGES model. IFSelect_Fail: if shape is null.

@subsubsection occt_1856844696_128830953123 Class IGESControl_Reader

General description

This object reads IGES files and translates their contents into OCCT shapes. All definitions in IGES version 5.3 are recognized but only geometric and topologic entities can be translated. Data, which cannot be translated, is loaded with the file but during translation it is ignored. The translation of the IGES model into the OCCT model goes through the following steps: * loading a file into memory, * checking file consistency, * setting translation parameters, * performing the translation itself, * fetching the results.

The resulting OCCT objects belong to topologic shapes. The geometric objects (2D and 3D) are constructed in intermediate steps and serve as a support for topologic entities.
Each successful translation operation outputs one shape. A series of translations gives a list of shapes.
Inheritance
IGESToBRep_Reader This class complements IGESToBRep_Reader class:

• deals directly with WorkSession object,
• computes the list of IGES entities matching specified criteria,
• performs translation of a list of entities and the ones specified by handle,
• outputs the results of checking and translating.

Methods

Constructors:

* IGESControl_Reader (); Purpose: Creates a reader from scratch and with a new WorkSession object. * IGESControl_Reader (const Handle(XSControl_WorkSession)& WS, const Standard_Boolean scratch); Purpose: Defines work session for the reader. If scratch is True the new model will be created in the work session.

Methods for dealing with WorkSession object

* IGESControl_Reader::SetWS void SetWS ( const Handle(XSControl_WorkSession)& WS, const Standard_Boolean scratch = Standard_True); Purpose: Defines the work session for the reader. If scratch is True the new model will be created in the work session object. * IGESControl_Reader::WS Handle_XSControl_WorkSession() const; Purpose: Returns the used work session object.

Method for loading an IGES file into memory

* IGESControl_Reader::ReadFile IFSelect_ReturnStatus ReadFile(const Standard_CString filename); Purpose: Loads and memorizes an IGES file in memory. Returns: IFSelect_RetDone: the file was successfully read IFSelect_RetVoid: no file found IFSelect_RetError: an error occurred during reading See also: IGESToBRep_Reader::LoadFile()

Methods for selecting entities to transfer

* IGESControl_Reader::GiveList Handle_TColStd_HSequenceOfTransient GiveList( const Standard_CString first = ;;, const Standard_CString second = ;;); Purpose: Returns a list of entities from the model according to the following rules: * if first and second are empty - the list of roots for transfer, * if first is a number or label of an entity - this entity itself, * if first is a list of numbers/labels separated by commas - these entities, * if first is a name of a selection in work session and second is not defined - the standard result of this selection, * if first is a name of a selection and second is defined - the criterion defined by second is applied to result of first selection Remarks: if second is erroneous it is ignored. Handle_TColStd_HSequenceOfTransient GiveList( const Standard_CString first, const Handle(Standard_Transient)& ent) ; Purpose: Returns a list of entities from the model according to the following rules: * if first is a selection name and second is an entity or a list of entities (as a HSequenceOfTransient) - the standard result of this selection is applied to this list. Remarks: if first is erroneous, a null handle is returned.

Methods for performing translation

* IGESControl_Reader::TransferEntity Standard_Boolean TransferEntity(const Handle(Standard_Transient)& start) ; Purpose: Performs the translation of the entity specified by its handle. Returns False if an entity is not in the Model, else returns the result of the transfer. * IGESControl_Reader:: TransferList Standard_Integer TransferList( const Handle(TColStd_HSequenceOfTransient)& list) ; Purpose: Performs the translation of the list of entities. Returns the number of successful transfers.

Methods for printing statistics

* IGESControl_Reader:: PrintCheckLoad void PrintCheckLoad( const Standard_Boolean failsonly, const IFSelect_PrintCount mode) const ; Purpose: Displays the check results on file entities. If failsonly is True prints only "Fail" messages, otherwise all messages. mode determines the contents and the order of messages: IFSelect_ItemsByEntity - sequential list of messages per entity, IFSelect_CountByItem - counts the number of entities per message, IFSelect_ShortByItem - the same function but also of the first five entities, IFSelect_ListByItem - the same but displays the rank numbers of all (not only five) entities, IFSelect_EntitiesByItem - the same plus it displays the Directory Entry number for each entity * IGESControl_Reader:: PrintCheckTransfer void PrintCheckTransfer( const Standard_Boolean failsonly, const IFSelect_PrintCount mode) const; Purpose: Displays the checking results of the last transfer. The parameters play the same role as in PrintCheckLoad. * IGESControl_Reader:: PrintStatsTransfer void PrintStatsTransfer( const Standard_Integer what, const Standard_Integer mode = 0) const; Purpose: Displays all available statistics of the last transfer on the default trace file. The returned information is filtered by giving parameters. what defines what kind of statistics are to be printed: 0 - basic figures, 1 - root results, 2 - all recorded (roots, intermediate, checked entities), 3 - abnormal records, 4 - warnings and fails messages, 5 - only fail messages mode is used according to what: if what is 0 mode is ignored if what is 1, 2 or 3 mode defines the following: 0 - lists numbers of concerned entities in the model, 1 - for each entity, gives the number, label, type and result type and/or status (fail / warning...), 2 - for each entity, gives the maximum information (check result), 3 - counts per type of starting entity (class type), 4 - counts per result type and/or status, 5 - counts per couple (starting type / result type/status), 6 – does the same thing plus gives for each item, the list of numbers of entities in the starting model if what is 4 or 5 - mode is treated as enumeration IFSelect_PrintCount. * IGESControl_Reader:: PrintTransferInfo void PrintTransferInfo( const IFSelect_PrintFail failwarn, const IFSelect_PrintCount mode) const; Purpose: Displays information concerning the last transfer on the default trace file according to the given parameters: mode defines what will be printed: IFSelect_GeneralCount - general statistics (number of selected IGES entities, number of root IGES entities, number of resulting OCCT shapes, number of fail and warning messages), IFSelect_CountByItem - number of IGES entities per each message type and IGES type and form, IFSelect_ListByItem - number and a complete list of DE numbers of IGES entities per each message type and IGES type and form, IFSelect_ResultCount - number of resulting OCCT shapes per each type of the shape, IFSelect_Mapping - mapping of root IGES entities into OCCT shapes per IGES type and form and OCCT shape type. failwarn defines if only fail messages (if failwarn is IFSelect_FailOnly) or both fail and warning messages (if it is IFSelect_FailAndWarn) will be printed if mode is IFSelect_CountByItem or IFSelect_ListByItem. @subsubsection occt_1856844696_128830953124 Class IGESControl_Writer

General description

This class is intended to create and write an IGES file out of OCCT models. IGES files produced by this component conform to IGES version 5.3. This component gives a possibility to write an IGES file containing either geometric entities (conformant to IGES version less than 5.1) only or BRep entities (conformant to IGES version up to and including 5.3) as well. The writing mode is chosen by specifying the appropriate parameter. The translation of an OCCT model (which can be a 2D or 3D geometric object or a topologic shape) into an IGES file is fulfilled in the following steps: 1.    initializing the file, 2.    setting the translation parameters, 3.    performing the translation itself, 4.    writing the IGES file. Export to the IGES file can be performed on the basis of either an already existing IGES model (representation of the IGES file in memory) or a new one. The former case gives an opportunity to add geometric/topologic OCCT objects into an IGES model (file) that already exists.

Methods

Constructors:

* IGESControl_Writer(); Purpose: Creates a writer object with the default unit and write mode (Face). * IGESControl_Writer( const Standard_CString unit, const Standard_Integer modecr = 0 ); Purpose: Creates a writer object with the given values for the unit and write mode. unit is the name of the units that are accepted by IGES in the upper case ("IN" or "INCH" for inches, "MM" for millimeters and so on), modecr corresponds to write mode: 0 - Face (default), 1 - BRep * IGESControl_Writer( const Handle(IGESData_IGESModel)& model, const Standard_Integer modecr = 0); Purpose: Creates a writer object with an already prepared IGES model and write mode.

Methods dealing with IGES models

* IGESControl_Writer:: Model Handle_IGESData_IGESModel Model() const; Purpose: Returns the produced model. * IGESControl_Writer:: ComputeModel() ; void ComputeModel() ; Purpose: Prepares the model before writing by setting the required statuses inside the model.

Methods dealing with transfer processes

* IGESControl_Writer:: SetTransferProcess void SetTransferProcess(const Handle(Transfer_FinderProcess)& TP) ; Purpose: Sets the FinderProcess object for the writer. * IGESControl_Writer:: TransferProcess Handle_Transfer_FinderProcess TransferProcess() const; Purpose: Returns the FinderProcess object (containing final results and messages if any).

Methods for performing translation

* IGESControl_Writer:: AddShape Standard_Boolean AddShape(const TopoDS_Shape& sh) ; Purpose: Translates a shape sh to IGES entities and adds them to the model. Returns True if done, False if sh is not suitable for IGES or is null. * IGESControl_Writer:: AddGeom Standard_Boolean AddGeom(const Handle(Standard_Transient)& geom) ; Purpose: Translates geom (which must be a curve or a surface) to IGES entities and adds them to the model. Returns True if done, False if geom is neither a surface nor a curve suitable for IGES or is null. * IGESControl_Writer:: AddEntity Standard_Boolean AddEntity(const Handle(IGESData_IGESEntity)& ent) ; Purpose: Adds an IGES entity (and the ones it references) to the model. Returns False if ent is null.

Methods for writing an IGES file

* IGESControl_Writer:: Write Standard_Boolean Write( Standard_OStream& S, const Standard_Boolean fnes = Standard_False) ; Standard_Boolean Write( const Standard_CString file, const Standard_Boolean fnes = Standard_False) ; Purpose: Prepares (call ComputeModel()) and writes the model to the stream S or to the file file. Returns True if the operation was correctly performed, False in case of error. If mode fnes is equal to True, the resulting file will be written in the FNES format.

Method for obtaining statistics

* IGESControl_Writer:: PrintStatsTransfer void PrintStatsTransfer( const Standard_Integer what, const Standard_Integer mode = 0) const; Purpose: Intended to display all statistics on the last performed translation. Remarks: At the present moment does nothing (an empty method). Package IGESToBRep

@subsubsection occt_1856844696_128830953125 General description Performs the actual translation of IGES entities into OCCT objects.
This package recognizes an IGES entity, performs its translation into an OCCT object (which can be 2D or 3D geometric objects, topologic shapes or transformation matrices) and returns the resulting shapes with associated messages (if there are any) occurred during the translation.
Those IGES entities that can be translated into OCCT objects by this package are given in the following table:

Finally, all geometric IGES entities (curves and surfaces) are translated into topologic shapes. OCCT geometric objects serve as a support for topology.
@subsubsection occt_1856844696_128830953126 Class IGESToBRep_Reader

General description

This class reads IGES files and translates their contents into OCCT shapes. This class provides basic tools for loading, checking and translating IGES files into OCCT topologic shapes. It is complemented with more high-level features by class IGESControl_Reader. The functionalities provided by this class are the following: * loading a file into memory, * checking an IGES model in memory, * translating all root entities or one entity specified by its rank number into OCCT shapes, * fetching the results.

Methods

Constructors:

* IGESToBRep_Reader(); Purpose: Performs initialization calling IGESAppli::Init() and IGESSolid::Init(), creates a new Actor object for transfer.

Method for loading an IGES file into memory

* IGESToBRep_Reader:: LoadFile Standard_Integer LoadFile(const Standard_CString filename) ; Purpose: Loads an IGES file filename into memory calling IGESFile_Read(), sets the returned IGES model (representing the loaded IGES file) calling SetModel().

Method for checking an IGES file

* IGESToBRep_Reader:: Check Standard_Boolean Check(const Standard_Boolean withprint) const; Purpose: Performs checking of a loaded IGES file calling Interface_CheckTool and Interface_CheckIterator. If withprint is True outputs the results of checking to the default trace file.

Methods for preparing the transfer process

* IGESToBRep_Reader:: SetModel void SetModel(const Handle(IGESData_IGESModel)& model) ; Purpose: Sets a new IGES model object. Clears the list of translated shapes (if there are any), sets a new transfer process object. * IGESToBRep_Reader:: Model Handle_IGESData_IGESModel Model() const; Purpose: Returns the used IGES model object. * IGESToBRep_Reader:: SetTransientProcess void SetTransientProcess(const Handle(Transfer_TransientProcess)& TP) ; Purpose: Sets the transfer process object. * IGESToBRep_Reader:: TransientProcess Handle_Transfer_TransientProcess TransientProcess() const; Purpose: Returns the used transfer process object. * IGESToBRep_Reader:: Actor Handle_IGESToBRep_Actor Actor() const; Purpose: Returns the used actor object. * IGESToBRep_Reader::Clear void Clear() ; Purpose: Clears the list of translated shapes.

Methods for translation

* IGESToBRep_Reader:: TransferRoots void TransferRoots(const Standard_Boolean onlyvisible = Standard_True) Purpose: Performs the translation of root entities (ones that are not referenced by others). If onlyvisible is True, translates only visible entities (with Blank status equal to 0). Sets the continuity in accordance with the static parameter read.iges.bspline.continuity. If parameter read.maxprecision.mode is set to 1, calls to ShapeTool_Utils::LimitTolerance() for the resulting shape with parameters 0 and the maximum between read.maxprecision.val and the basis tolerance of processor. * IGESToBRep_Reader:: Transfer Standard_Boolean Transfer(const Standard_Integer num) ; Purpose: Performs the translation of an entity specified by its rank number. Creates an object of class IGESToBRep_CurveAndSurface and sets: 3D precision (taking its value either from the file or from the work session in accordance with the static parameter read.precision.mode), the approximation mode parameter in accordance with static the parameter read.iges.bspline.approxd1.mode, the mode for a preferred computation of curves on a surface in accordance with the static parameter read.surfacecurve.mode, the spline continuity parameter in accordance with the static parameter read.iges.bspline.continuity, the transfer process object taken from itself. Once all the fields have been filled out this method calls method TransferGeometry() with the IGES entity calculated by its rank number to obtain the OCCT shape. Like method TransferRoots() this one also limits the tolerance if the static parameter read.maxprecision.mode is set to 1. Returns False if num is greater than the number of entities in the model or less than 1, otherwise returns True even if there was an exception during the transfer.

Methods for fetching the results

* IGESToBRep_Reader:: IsDone Standard_Boolean IsDone() const; Purpose: Returns True if the last transfer was successful. * IGESToBRep_Reader:: NbShapes Standard_Integer NbShapes() const; Purpose: Returns the number of shapes recorded in the result. * IGESToBRep_Reader:: Shape TopoDS_Shape Shape(const Standard_Integer num = 1) const; Purpose: Returns the result number num where num is an integer between 1 and NbShapes(). If not returns a null shape. * IGESToBRep_Reader:: OneShape TopoDS_Shape OneShape() const; Purpose: Returns all results in a single shape, which is: * a null shape if there are no results, * in the case of a single result, only that shape, * a compound that lists all the results if there are several resulting shapes. @subsection occt_1856844696_12883095313 Package IGESData @subsubsection occt_1856844696_128830953131 General description This package defines general objects for dealing with the IGES interface. It gives a basic description of the IGES interface: * defines the Model for IGES (class IGESData_IGESModel), * defines the Protocol tool specific for IGES (class IGESData_Protocol) * defines the basic class IGESData_IGESEntity describing abstract IGES entity * defines classes derived from IGESEntity and representing general IGES entities (IGESData_LineFontEntity, IGESData_TransfEntity, IGESData_SingleParentEntity, etc.), @subsubsection occt_1856844696_128830953132 Class IGESData_IGESModel

General description

Gives an access to the general data in the Start and the Global sections of an IGES file. Defines a model specific for IGES. An IGES file includes the following sections: Start, Global, Directory Entry, Parameter Data, Terminate Inheritance: Interface_InterfaceModel MMgt_TShared Standard_Transient

Methods

Constructor

* IGESData_IGESModel (); Purpose: Creates an empty IGES Model.

Methods for initializing

* IGESData_IGESModel::ClearHeader void ClearHeader() ; Purpose: Erases all the data in the Start and Global sections. * IGESData_IGESModel::NewEmptyModel Handle_Interface_InterfaceModel NewEmptyModel() const; Purpose: Returns a new Empty Model of the same type as this object, i.e. of type IGESData_IGESModel.

Methods for dealing with the Start and the Global sections

* IGESData_IGESModel::DumpHeader void DumpHeader(Standard_OStream& S, const Standard_Integer level = 0) const; Remark: the Integer parameter is intended to be used as a level indicator, but not used for the moment. * IGESData_IGESModel::StartSection Handle_TColStd_HSequenceOfHAsciiString StartSection() const; Purpose: Returns the Start section of the Model as a list of lines. * IGESData_IGESModel::NbStartLines Standard_Integer NbStartLines() const; Purpose: Returns the number of the lines in the Start section. * IGESData_IGESModel::StartLine Standard_CString StartLine(const Standard_Integer num) const; Purpose: Returns a line from the Start section specified by number num. Remark: An empty string is returned if number num is out of range [1, NbStartLines()]. * IGESData_IGESModel::ClearStartSection void ClearStartSection() ; Purpose: Clears the Start section. * IGESData_IGESModel::SetStartSection void SetStartSection(const Handle(TColStd_HSequenceOfHAsciiString)& list, const Standard_Boolean copy = Standard_True) ; Purpose: Sets a new Start section from the list of strings list, copying it if copy is True (by default) or pointing to the list if copy is False. * IGESData_IGESModel::AddStartLine void AddStartLine(const Standard_CString line, const Standard_Integer atnum = 0) ; Purpose: Adds a new string to the end of the existing Start section if atnum is 0 or not given, or before the atnum-th line. Remark: If a number is out of range [0, NbStartLines()], the line is added at the end of section. * IGESData_IGESModel::GlobalSection const IGESData_GlobalSection& GlobalSection() const; Purpose: Returns the Global section of the Model. * IGESData_IGESModel::SetGlobalSection. void SetGlobalSection(const IGESData_GlobalSection& header) ; Purpose: Sets the Model's Global section. * IGESData_IGESModel::ApplyStatic Standard_Boolean ApplyStatic(const Standard_CString param = ;;) ; Purpose: Sets some parameters of the Global section to those defined by static parameters (see parameters of translation). The allowed values for param (all by default) are: receiver, author and company (these are acronyms of static parameters). Returns True when done and if param is given, False if param is unknown or empty. Remark: To set a unit into the Global section use the IGESData_BasicEditor class. See also: User’s Guide: Parameters of translation. * IGESData_IGESModel::GetFromAnother void GetFromAnother(const Handle(Interface_InterfaceModel)& other) ; Purpose: Takes the Global section from another Model. * IGESData_IGESModel::VerifyCheck virtual void VerifyCheck(Interface_Check& ach) const; Purpose: Checks whether the Global section contains valid data according to the IGES specification. If the Global section is correct this method adds nothing into ach, but if not the method adds fail messages. * IGESData_IGESModel::SetLineWeights void SetLineWeights(const Standard_Real defw) ; Purpose: Sets LineWeights of entities according to the Global section (MaxLineWeight and LineWeightGrad values) or to a default value (defw) for undefined weights.

Methods for dealing with IGES entities

* IGESData_IGESModel::ClearLabels() ; void ClearLabels() ; Purpose: Erases labels. Not yet implemented. * IGESData_IGESModel::PrintLabel void PrintLabel(const Handle(Standard_Transient)& ent, Standard_OStream& S) const; Purpose: Prints the Directory Entry number of a given entity, i.e. 'Dnn' where Dnn=2*number-1on the stream S. * IGESData_IGESModel::StringLabel Handle_TCollection_HAsciiString StringLabel (const Handle(Standard_Transient)& ent) const; Purpose: Returns a string with a Directory Entry number of a given entity, i.e. a string 'Dnn' where Dnn=2*number-1. * IGESData_IGESModel::Entity Handle_IGESData_IGESEntity Entity(const Standard_Integer num) const; Purpose: Returns an entity given by its rank number. * IGESData_IGESModel::DNum Standard_Integer DNum(const Handle(IGESData_IGESEntity)& ent) const; Purpose: Returns the DE Number of an entity, i.e. 2*Number(ent)-1, or 0 if ent is unknown from this Model. @subsubsection occt_1856844696_128830953133 Class IGESData_IGESEntity

General description

Represents an abstract IGES entity. This class provides an access to common IGES entity fields (TypeNumber, TransformationMatrix, etc.). This class is a basic one for other classes complementing it to represent a certain IGES entity. Refer to the IGES specification for more details. Inheritance MMgt_TShared Standard_Transient

Methods

Constructors:

* IGESData_IGESEntity(); Purpose: Creates an empty object. Sets all values to defaults (calls Clear()).

Methods for initializing fields of object.

* IGESData_IGESEntity::Clear void Clear() ; Purpose: Clears all fields of the object. * IGESData_IGESEntity::InitTypeAndForm void InitTypeAndForm( const Standard_Integer typenum, const Standard_Integer formnum) ; Purpose: Sets the Type and Form Numbers to new values. Remarks: Private method. Reserved for special use. * IGESData_IGESEntity::InitDirFieldEntity void InitDirFieldEntity( const Standard_Integer fieldnum, const Handle(IGESData_IGESEntity)& ent) ; Purpose: Sets a directory field to an ent of any kind (see DirFieldEntity() for more details). Remarks: If fieldnum is not equal to values listed in DirFieldEntity(), this method does nothing. * IGESData_IGESEntity::InitTransf void InitTransf(const Handle(IGESData_TransfEntity)& ent) ; Purpose: Sets the Transf or erases it if ent is null. * IGESData_IGESEntity::InitView void InitView(const Handle(IGESData_ViewKindEntity)& ent) ; Purpose: Sets the View or erases it if ent is null. * IGESData_IGESEntity::InitLineFont void InitLineFont( const Handle(IGESData_LineFontEntity)& ent, const Standard_Integer rank = 0) ; Purpose: Sets the LineFont. If ent is null the RankLineFont is set to rank, otherwise it is set to a negative value. * IGESData_IGESEntity::InitLevel void InitLevel( const Handle(IGESData_LevelListEntity)& ent, const Standard_Integer val = 0) ; Purpose: Sets the Level. If ent is null the DefLevel is set to val, otherwise it is set to a negative value. * IGESData_IGESEntity::InitColor void InitColor( const Handle(IGESData_ColorEntity)& ent, const Standard_Integer rank = 0) ; Purpose: Sets the Color. If ent is null the DefColor is set to rank, otherwise it is set to a negative value. * IGESData_IGESEntity::InitStatus void InitStatus( const Standard_Integer blank, const Standard_Integer subordinate, const Standard_Integer useflag, const Standard_Integer hierarchy) ; Purpose: Sets the flags of the Directory Part. * IGESData_IGESEntity::SetLabel void SetLabel( const Handle(TCollection_HAsciiString)& label, const Standard_Integer sub = -1) ; Purpose: Sets a new Label to an Entity. If sub is given, it sets the value of SubScriptNumber, else SubScriptNumber is erased. * IGESData_IGESEntity::InitMisc void InitMisc( const Handle(IGESData_IGESEntity)& str, const Handle(IGESData_LabelDisplayEntity)& lab, const Standard_Integer weightnum) ; Purpose: Sets data or erases it if it is given as null (zero for weightnum): str for Structure, lab for LabelDisplay, weightnum for WeightNumber * IGESData_IGESEntity::SetLineWeight void SetLineWeight( const Standard_Real defw, const Standard_Real maxw, const Standard_Integer gradw) ; Purpose: Computes and sets the ;true; line weight according to IGES rules from the global data MaxLineWeight (maxw) and LineWeightGrad (gradw), or sets it to defw (Default) if LineWeightNumber is null Remarks: If gradw is zero, there is division by zero in this method.

Methods for querying the corresponding fields of an IGES entity.

* IGESData_IGESEntity::IGESType IGESData_IGESType IGESType() const; Purpose: Returns information on the IGES type of an entity including the type and the form of that entity. * IGESData_IGESEntity::TypeNumber Standard_Integer TypeNumber() const; Purpose: Returns the IGES Type number. * IGESData_IGESEntity::FormNumber Standard_Integer FormNumber() const; Purpose: Returns the IGES Form number. * IGESData_IGESEntity::DirFieldEntity Handle_IGESData_IGESEntity DirFieldEntity(const Standard_Integer fieldnum) const; Purpose: Returns the Entity that is recorded for a given Field Number fieldnum where: 3 - Structure 4 - LineFont 5 - LevelList 6 - View 7 - Transf(ormation Matrix) 8 - LabelDisplay 13 - Color. In a case of other values it returns a null handle.

• IGESData_IGESEntity::HasStructure
  Standard_Boolean HasStructure() const;
  Purpose: Returns True if an IGES entity is defined with a structure (it is normally reserved for certain classes, such as Macros).

• IGESData_IGESEntity::Structure
  Handle_IGESData_IGESEntity Structure() const;
  Purpose: Returns the Structure (used by some types of IGES entities only), returns a null handle if Structure is not defined.

• IGESData_IGESEntity::DefLineFont
  IGESData_DefType DefLineFont() const;
  Purpose: Returns the definition status of LineFont.

• IGESData_IGESEntity::RankLineFont Standard_Integer RankLineFont() const;
  Purpose: Returns LineFont definition as an integer if it is defined as Rank. If LineFont is defined as an Entity, returns a negative value

• IGESData_IGESEntity::LineFont
  Handle_IGESData_LineFontEntity LineFont() const;
  Purpose: Returns LineFont as an entity if it is defined as Reference. Returns a null handle if DefLineFont is not ;DefReference;.

• IGESData_IGESEntity::DefLevel
  IGESData_DefList DefLevel() const;
  Purpose: Returns the definition status of Level.

• IGESData_IGESEntity::Level Standard_Integer Level() const;
  Purpose: Returns Level definition as an integer.

• IGESData_IGESEntity::LevelList
  Handle_IGESData_LevelListEntity LevelList() const;
  Purpose: Returns LevelList if Level is defined as List. Returns a null handle if DefLevel is not ;DefSeveral;.

• IGESData_IGESEntity::DefView IGESData_DefList DefView() const;
  Purpose: Returns the definition status of View (None,One or Several).

• IGESData_IGESEntity::View Handle_IGESData_ViewKindEntity View() const;
  Purpose: Returns the View (either Single or List) if it is defined. Returns a null handle if it is not defined.

• IGESData_IGESEntity::SingleView
  Handle_IGESData_ViewKindEntity SingleView() const;
  Purpose: Returns View as Single, if defined as One. Returns a null handle if DefView is not ;DefOne;.

• IGESData_IGESEntity::ViewList
  Handle_IGESData_ViewKindEntity ViewList() const;
  Purpose: Returns View as a List. Returns a null handle if DefView is not ;DefSeveral;.

• IGESData_IGESEntity::HasTransf
  Standard_Boolean HasTransf() const;
  Purpose: Returns True if a Transformation Matrix is defined.

• IGESData_IGESEntity::Transf Handle_IGESData_TransfEntity Transf() const;
  Purpose: Returns the Transformation Matrix (under IGES definition). Returns a null handle if there is none. Remarks: For a more complete use, see Location & CompoundLocation.

• IGESData_IGESEntity::HasLabelDisplay
  Standard_Boolean HasLabelDisplay() const;
  Purpose: Returns True if the LabelDisplay mode is defined for this entity.

• IGESData_IGESEntity::LabelDisplay
  Handle_IGESData_LabelDisplayEntity LabelDisplay() const;
  Purpose: Returns the LabelDisplay, if there is one; else returns a null handle.

• IGESData_IGESEntity::BlankStatus
  Standard_Integer BlankStatus() const;
  Purpose: Returns the Blank Status (0 - visible, 1 - blanked).

• IGESData_IGESEntity::SubordinateStatus
  Standard_Integer SubordinateStatus() const;
  Purpose: Returns the Subordinate Switch (0-1-2-3)

• IGESData_IGESEntity::UseFlag Standard_Integer UseFlag() const;
  Purpose: Returns the Use Flag (0 to 5) of an entity.

• IGESData_IGESEntity::HierarchyStatus
  Standard_Integer HierarchyStatus() const;
  Purpose: Returns the Hierarchy status (0-1-2).

• IGESData_IGESEntity::LineWeightNumber
  Standard_Integer LineWeightNumber() const;
  Purpose: Returns the LineWeight Number (0 if it is not defined). See also: LineWeight.

• IGESData_IGESEntity::LineWeight
  Standard_Real LineWeight() const;
  Purpose: Returns ;true; LineWeight, computed from LineWeightNumber and the global parameter of the Model by call to SetLineWeight.

• IGESData_IGESEntity::DefColor
  IGESData_DefType DefColor() const;
  Purpose: Returns the definition status of Color.

• IGESData_IGESEntity::RankColor Standard_Integer RankColor() const;
  Purpose: Returns the Color definition as an Integer (if defined as Rank). If Color is defined as an Entity, returns a negative value.

• IGESData_IGESEntity::Color Handle_IGESData_ColorEntity Color() const;
  Purpose: Returns the Color as an Entity (if defined as Reference) or a null handle if Color Definition is not ;DefReference;.

• IGESData_IGESEntity::CResValues
  Standard_Boolean CResValues( const Standard_CString res1,
  const Standard_CString res2) const; Purpose: Fills res1 and res2 with inner ;reserved; alphanumeric fields theRes1 and theRes2. Returns False if both are blank, otherwise returns True. Warning: Both must be of a length equal to at least 9 characters. The contents of res1 and res2 are modofied. The 9-th character becomes null.

• IGESData_IGESEntity::HasShortLabel
  Standard_Boolean HasShortLabel() const;
  Purpose: Returns True if ShortLabel is not null.

• IGESData_IGESEntity::ShortLabel Handle_TCollection_HAsciiString ShortLabel() const;
  Purpose: Returns label value as a string (null if ShortLabel is blank).

• IGESData_IGESEntity::HasSubScriptNumber
  virtualStandard_Boolean HasSubScriptNumber() const;
  Purpose: Returns True if SubScript Number is defined.

• IGESData_IGESEntity::SubScriptNumber
  Standard_Integer SubScriptNumber() const;
  Purpose: Returns SubScript Number as an integer (0 if not defined).

• IGESData_IGESEntity::HasOneParent()
  Standard_Boolean HasOneParent() const;
  Purpose: Returns True if an entity has one and only one parent, defined by a SingleParentEntity Type Associativity (explicit sharing). Remarks: Thus, implicit sharing remains defined at the model level.
  See class ToolLocation.

• IGESData_IGESEntity::UniqueParent() const; Handle_IGESData_IGESEntity UniqueParent() const;
  Purpose: Returns the Unique Parent (if it is the one). Exceptions: Interface_InterfaceError if there are either several or no parents.

• IGESData_IGESEntity::Location() gp_GTrsf Location() const;
  Purpose: Returns the entity Location given by Transf in the Directory Part (see above). Considers local location only (not taking into account the parent's one - see CompoundLocation for that). If no Transf is defined, returns Identity.

• IGESData_IGESEntity::VectorLocation()
  gp_GTrsf VectorLocation() const;
  Purpose: Returns the Translation part of a local location (as for Location).

• IGESData_IGESEntity::CompoundLocation()
  gp_GTrsf CompoundLocation() const;
  Purpose: Returns the location of this object combined with CompoundLocation of its Parent (i.e. can be recursive). If the Parent is not single (see HasOneParent) returns Location.

• IGESData_IGESEntity::HasName()
  Standard_Boolean HasName() const;
  Purpose: Says if a Name is defined as Short Label or as Name Property. (Property is looked for first, otherwise ShortLabel is considered).

• IGESData_IGESEntity::NameValue()
  Handle_TCollection_HAsciiString NameValue() const;
  Purpose: Returns the Name value as a String (Property Name or ShortLabel). If SubNumber is defined, it is concatenated after ShortLabel as follows - label (number). Ignored in case of Property Name.

Methods for dealing with associativities and properties.

* IGESData_IGESEntity::ArePresentAssociativities() Standard_Boolean ArePresentAssociativities() const; Purpose: Returns True if the Entity is defined with an Associativity list, even an empty one (i.e., the file is of 0 length). Otherwise returns False (the file contains no identification concerning this list at all). * IGESData_IGESEntity::NbAssociativities Standard_Integer NbAssociativities() const; Purpose: Returns the number of recorded associativities (0 if no list is defined). * IGESData_IGESEntity::Associativities Interface_EntityIterator Associativities() const; Purpose: Returns the Associativity List in the form of an EntityIterator. * IGESData_IGESEntity::NbTypedAssociativities Standard_Integer NbTypedAssociativities const Handle(Standard_Type)& atype) const; Purpose: Returns information on how many Associativities have the given type.

• IGESData_IGESEntity::TypedAssociativity
  Handle_IGESData_IGESEntity TypedAssociativity
  (const Handle(Standard_Type)& atype) const; Purpose: Returns the Associativity of a given Type (if one exists) Exceptions: Interface_InterfaceError if there is none or more than one associativity.
• IGESData_IGESEntity::AddAssociativity void AddAssociativity(const Handle(IGESData_IGESEntity)& ent) ;
  Purpose: Adds an Associativity to the list (called by Associate only). Exceptions: Standard_NullObject if ent is null.
• IGESData_IGESEntity::RemoveAssociativity
  void RemoveAssociativity(const Handle(IGESData_IGESEntity)& ent) ;
  Purpose: Removes an Associativity from the list (called by Dissociate). Exceptions: Standard_NullObject if ent is null.
• IGESData_IGESEntity::LoadAssociativities
  void LoadAssociativities(const Interface_EntityList& list) ;
  Purpose: Loads a complete List of Asociativities (used during Read or Copy operations).
• IGESData_IGESEntity::ClearAssociativities
  void ClearAssociativities() ;
  Purpose: Removes all associativities at once.
• IGESData_IGESEntity::Associate
  void Associate(const Handle(IGESData_IGESEntity)& ent) const;
  Purpose: Sets this object to the Associativity list of another Entity. If ent is a null object, method does nothing.
• IGESData_IGESEntity::Dissociate void Dissociate(const Handle(IGESData_IGESEntity)& ent) const;
  Purpose: Removes this object from the Associativity list of another Entity. If ent is a null object, method does nothing.
• IGESData_IGESEntity::ArePresentProperties
  Standard_Boolean ArePresentProperties() const;
  Purpose: Returns True if the Entity is defined with a Property list, even an empty one (i.e., the file is of 0 length). Otherwise, returns False (file contains no identification concerning this list at all).
• IGESData_IGESEntity::NbProperties()
  Standard_Integer NbProperties() const;
  Purpose: Returns the number of recorded properties (0 if no list is defined)
• IGESData_IGESEntity::Properties()
  Interface_EntityIterator Properties() const;
  Purpose: Returns the Property List in the form of an EntityIterator
• IGESData_IGESEntity::NbTypedProperties
  Standard_Integer NbTypedProperties
  (const Handle(Standard_Type)& atype) const; Purpose: Returns information on how many Properties have a given type
• IGESData_IGESEntity::TypedProperty Handle_IGESData_IGESEntity TypedProperty
  (const Handle(Standard_Type)& atype) const; Purpose: Returns the Property of a given Type (if only one exists) Exceptions: Interface_InterfaceError if there is none or more than one Properties.
• IGESData_IGESEntity::AddProperty
  void AddProperty(const Handle(IGESData_IGESEntity)& ent) ;
  Purpose: Adds a Property to the list. Exceptions: Standard_NullObject if entis null.
• IGESData_IGESEntity::RemoveProperty
  void RemoveProperty(const Handle(IGESData_IGESEntity)& ent) ;
  Purpose: Removes a Property from the list. Exceptions: Standard_NullObject if entis null.
• IGESData_IGESEntity::LoadProperties
  void LoadProperties(const Interface_EntityList& list) ;
  Purpose: Loads a complete List of Properties (used during Read or Copy operations).
• IGESData_IGESEntity::ClearProperties() ; void ClearProperties() ;
  Purpose: Removes all properties at once

@section occt_1856844696_722523915 Using XSTEPDRAW @subsection occt_1856844696_7225239151 XSDRAWIGES Overview XSTEPDRAW UL is intended for creating executables for testing XSTEP interfaces interactively in the DRAW environment. It provides an additional set of DRAW commands specific for the data exchange tasks, which allow loading and writing data files and analysis of resulting data structures and shapes.
This paragraph 5 is divided into several sections. Sections 5.3 and 5.5 deal with reading and writing of IGES files and are intended specifically for the IGES processor, sections 5.2 and 5.4 describe some general tools for setting parameters and analyzing the data. Most of them are independent of the norm being tested. Additionally, a table of mentioned DRAW commands is provided.
NOTE In the description of commands, square brackets ([]) are used to indicate optional parameters. Parameters given in the angle brackets () and sharps (#) are to be substituted by an appropriate value. When several exclusive variants are possible, vertical dash (|) is used.
@subsection occt_1856844696_7225239152 Setting interface parameters A set of parameters for importing and exporting IGES files is defined in the XSTEP resource file. In XSTEPDRAW, these parameters can be viewed or changed using command
Draw param [parameter_name [value]]
Command param with no arguments gives a list of all parameters with their values. When argument parameter_name is specified, information about this parameter is printed (current value and short description).
The third argument is used to set a new value of the given parameter. The result of the setting is printed immediately.
During all interface operations, the protocol of the process (fail and warning messages, mapping of the loaded entities into OCCT shapes etc.) can be output to the trace file. Two parameters are defined in the DRAW session: trace level (integer value from 0 to 9, default is 0), and trace file (default is a standard output).
Command xtrace is intended to view and change these parameters:
Draw xtrace

• prints current settings (e.g.: ;Level=0 - Standard Output;);
  Draw xtrace #
• sets the trace level to the value #;
  Draw xtrace tracefile.log
• sets the trace file as tracefile.log; and
  Draw xtrace .
• directs all messages to the standard output.

@subsection occt_1856844696_7225239153 Reading IGES files For a description of parameters used in reading an IGES file refer to 2.3.3 ;Setting the translation parameters ;.
These parameters are set by command param:

It is possible either only to load an IGES file into memory (i.e. to fill the model with data from the file), or to read it (i.e. to load and convert all entities to OCCT shapes).
Loading is done by the command Draw xload file_name Once the file is loaded, it is possible to investigate the structure of the loaded data. To learn how to do it see 5.4 Analyzing the transferred. Reading of an IGES file is done by the command
Draw igesbrep file_name result_shape_name [selection] Here a dot can be used instead of a filename if the file is already loaded by xload or igesbrep command. In that case, only conversion of IGES entities to OCCT shapes will be done. Command igesbrep will interactively ask the user to select a set of entities to be converted:

After the selected set of entities is loaded the user will be asked how loaded entities should be converted into OCCT shapes (e.g., one shape per root or one shape for all the entities). It is also possible to save loaded shapes in files, and to cancel loading. The second parameter of the igesbrep command defines the name of the loaded shape. If several shapes are created, they will get indexed names. For instance, if the last parameter was ‘s’, they will be s_1, ... s_N. selection specifies the scope of selected entities in the model, it is xst-transferrable-roots by default. An asterisk “” can be specified instead of iges-visible-transf-roots. For possible values for selection refer to 2.3.4. Instead of igesbrep the following commands can be used: Draw trimport file_name result_shape_name selection which outputs the result of translation of each selected entity into one shape, Draw trimpcomp file_name result_shape_name selection which outputs the result of translation of all selected entities into one shape (TopoDS_Compound for several entities). An asterisk “” can be specified instead of selection, it means xst-transferrable-roots. During the IGES translation, a map of correspondence between IGES entities and OCCT shapes is created. To get information on the result of translation of the given IGES entity the command Draw tpent # is used. To create an OCCT shape corresponding to an IGES entity the command Draw tpdraw # is used. To get the number of an IGES entity corresponding to an OCCT shape the command Draw fromshape shape_name is used. To clear the map of correspondences between IGES entities and OCCT shapes the command Draw tpclear is used. @subsection occt_1856844696_7225239154 Analyzing the transferred data The procedure of analysis of the data import can be divided into two stages:

1.    checking the file contents,
2.    estimation of translation results (conversion and validated ratios). @subsubsection occt_1856844696_72252391541 Checking file contents General statistics on the loaded data can be obtained by using command
   Draw data symbol The information printed by this command depends on the symbol specified:

There is a set of special objects, which can be used to operate with the loaded model. They can be of the following types:

A list of these objects defined in the current session can be printed in DRAW by command Draw listitems In the following commands if several selection arguments are specified the results of each following selection are applied to those of the one preceding it. Command
Draw givelist selection_name [selection_name] prints a list of loaded entities defined by selection argument. For possible values of selection_name please refer to 2.3.4. Command
Draw givecount selection_name [selection_name] prints a number of loaded entities defined by selection argument. For possible values of selection_name please refer to 2.3.4.
Three commands are used to calculate statistics on the entities in the model: Draw count counter [selection ...] Prints only a number of entities per each type matching the criteria defined by arguments. Draw sumcount counter [selection ...] Prints the total number of entities of all types matching the criteria defined by arguments and the largest number corresponding to one type. Draw listcount counter [selection ...] Prints a list of entities per each type matching the criteria defined by arguments. Optional selection argument, if specified, defines a subset of entities, which are to be taken into account. Argument counter should be one of the currently defined counters:

Command
Draw listtypes selection_name ... gives a list of entity types which were encountered in the last loaded file (with a number of IGES entities of each type). The list can be shown not for all entities but for a subset of them. This subset is defined by an optional selection argument.

Entities in the IGES file are numbered in the succeeding order. An entity can be identified either by its number (#) or by its label. Label is the letter ‘D’ followed by the index of the first line with the data for this entity in the Directory Entry section of the IGES file. The label can be calculated on the basis of the number as ‘D(2*# -1)’. For example, entity # 6 has label D11. To get a label for an entity with a known number, command
Draw elab # can be used.
In the same way, command
Draw enum D# prints a number for an entity with the given label. The content of an IGES entity can be obtained by using command Draw entity # level_of_information The list of entities referenced by a given entity and the list of entities referencing to it can be obtained by command Draw estat # @subsubsection occt_1856844696_72252391542 Estimating the results of reading IGES All of the following commands are available only after the data are converted into OCCT shapes (i.e. after command igesbrep). Command
Draw tpstat [*|?]symbol [selection] is provided to get all statistics on the last transfer, including the list of transferred entities with mapping from IGES to OCCT types, as well as fail and warning messages. The parameter *symbol *defines what information will be printed:

The sign ‘*’ before the parameters n, s, b, t, r makes it work on all entities (not only on roots). The sign ‘?’ before n, s, b, t limits the scope of information to invalid entities. Optional argument selection can limit the action of the command with a selected subset of entities. To get help, run this command without arguments. Example. Translation ratio on IGES faces. Draw: tpstat *l iges-faces The second version of the same command is TPSTAT (not capital spelling). Draw: TPSTAT symbol Symbol can be of the following values:

Sometimes the trimming contours of IGES faces (i.e., entity 141 for 143, 142 for 144) can be lost during translation due to fails. To obtain the number of lost trims and the number of corresponding IGES entities the command Draw tplosttrim [IGES_type] is used. It outputs the rank and DE numbers of faces that lost their trims and their numbers for each type (143, 144, 510) and their total number. If a face lost several of its trims it is output only once. Optional parameter IGES_type can be TrimmedSurface, BoundedSurface or Face to specify the only type of IGES faces. Example. Untrimmed 144 entities. Draw tplosttrim TrimmedSurface To get information on OCCT shape contents the command Draw statshape shape_name is used. It outputs the number of each kind of shapes (vertex, edge, wire, etc.) in a shape and some geometrical data (number of C0 surfaces, curves, indirect surfaces, etc.). Note. The number of faces is returned as a number of references. To obtain the number of single instances the standard command (from TTOPOLOGY executable) nbshapes can be used. To analyze the internal validity of a shape, command
Draw checkbrep shape_name expurged_shape_name is used. It checks the geometry and topology of a shape for different cases of inconsistency, like self-intersecting wires or wrong orientation of trimming contours. If an error is found, it copies bad parts of the shape with the names ; expurged_subshape_name #; and generates an appropriate message. If possible, this command also tries to find IGES entities the OCCT shape was produced from. expurged_shape_name will contain the original shape without invalid subshapes. To get information on tolerances of subshapes the command Draw tolerance shape_name [min [max] [symbol]] is used. It outputs maximum, average and minimum values of tolerances for each kind of subshapes having tolerances or it can output tolerances of all subshapes of the whole shape. When specifying min and max arguments this command outputs shapes with names shape_name... and their total number with tolerances in the range [min, max]. Symbol is used for specifying the kind of sub-shapes to analyze: v - for vertices, e - for edges, f - for faces, c - for shells and faces. @subsection occt_1856844696_7225239155 Writing an IGES file For a description of parameters used in reading an IGES file refer to 3.3.2 Setting the translation parameters. These parameters are set by command param:

Several shapes can be written in one file. To start writing a new file, enter command Draw newmodel Actually, command newmodel will clear the InterfaceModel to make it empty, and the next command will convert the specified shapes to IGES entities and put them into the InterfaceModel: Draw brepiges shape_name_1 [filename.igs] To write the prepared model to a file with name filename.igs, enter Draw writeall filename.igs @subsection occt_1856844696_7225239156 Index of useful commands

@section occt_1856844696_332489123 Reading from and writing to XDE @subsection occt_1856844696_3324891231 Description of the process @subsubsection occt_1856844696_33248912311 Loading an IGES file Before performing any other operation, you must load an IGES file with: IGESCAFControl_Reader reader(XSDRAW::Session(), Standard_False); IFSelect_ReturnStatus stat = reader.ReadFile(“filename.igs”); Loading the file only memorizes, but does not translate the data. @subsubsection occt_1856844696_33248912312 Checking the loaded IGES file This step is not obligatory. See the description of this step below in paragraph 2.3.2. @subsubsection occt_1856844696_33248912313 Setting parameters for translation to XDE See the description of this step below in paragraph 2.3.3. In addition, the following parameters can be set for XDE translation of attributes: • Parameter for transferring colors: reader.SetColorMode(mode); // mode can be Standard_True or Standard_False • Parameter for transferring names: reader.SetNameMode(mode); // mode can be Standard_True or Standard_False @subsubsection occt_1856844696_33248912314 Performing the translation of an IGES file to XDE The following function performs a translation of the whole document: Standard_Boolean ok = reader.Transfer(doc);
where ;doc; is a variable which contains a handle to the output document and should have a type Handle(TDocStd_Document). @subsubsection occt_1856844696_33248912315 Initializing the process of translation from XDE to IGES Here is how the process is initialized: IGESCAFControl_Writer aWriter(XSDRAW::Session(),Standard_False); @subsubsection occt_1856844696_33248912316 Setting parameters for translation from XDE to IGES The following parameters can be set for translation of attributes to IGES: • Parameter for transferring colors: aWriter.SetColorMode(mode); // mode can be Standard_True or Standard_False • Parameter for transferring names: aWriter.SetNameMode(mode); // mode can be Standard_True or Standard_False @subsubsection occt_1856844696_33248912317 Performing the translation of an XDE document to IGES You can perform the translation of a document by calling the function: IFSelect_ReturnStatus aRetSt = aWriter.Transfer(doc); where ;doc; is a variable which contains a handle to the input document for transferring and should have a type Handle(TDocStd_Document). @subsubsection occt_1856844696_33248912318 Writing an IGES file Write an IGES file with: IFSelect_ReturnStatus statw = aWriter.WriteFile(;filename.igs;); or IFSelect_ReturnStatus statw = writer.WriteFile (S); where S is OStream