The *Geom2dAPI_InterCurveCurve* class allows the evaluation of the intersection points (*gp_Pnt2d*) between two geometric curves (*Geom2d_Curve*) and the evaluation of the points of self-intersection of a curve.
-@image html /user_guides/modeling_algos/images/modeling_algos_image003.png "Intersection and self-intersection of curves"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image003.png "Intersection and self-intersection of curves"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image003.png,"Intersection and self-intersection of curves",420}
In both cases, the algorithm requires a value for the tolerance (Standard_Real) for the confusion between two points. The default tolerance value used in all constructors is *1.0e-6.*
-@image html /user_guides/modeling_algos/images/modeling_algos_image004.png "Intersection and tangent intersection"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image004.png "Intersection and tangent intersection"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image004.png,"Intersection and tangent intersection",420}
The algorithm returns a point in the case of an intersection and a segment in the case of tangent intersection.
The expression of a tangency problem generally leads to several results, according to the relative positions of the solution and the circles or straight lines in relation to which the tangency constraints are expressed. For example, consider the following
case of a circle of a given radius (a small one) which is tangential to two secant circles C1 and C2:
-@figure{/user_guides/modeling_algos/images/modeling_algos_image058.png,"Example of a Tangency Constraint"}
+@figure{/user_guides/modeling_algos/images/modeling_algos_image058.png,"Example of a Tangency Constraint",360}
This diagram clearly shows that there are 8 possible solutions.
This technique of qualification of a solution, in relation to the curves to which
it is tangential, can be used in all algorithms for constructing a circle or a straight
line by geometric constraints. Four qualifiers are used:
- * **Enclosing** - the solution(s) must enclose the argument;
- * **Enclosed** - the solution(s) must be enclosed by the argument;
- * **Outside** - the solution(s) and the argument must be external to one another;
- * **Unqualified** - the relative position is not qualified, i.e. all solutions apply.
+ * **Enclosing** -- the solution(s) must enclose the argument;
+ * **Enclosed** -- the solution(s) must be enclosed by the argument;
+ * **Outside** -- the solution(s) and the argument must be external to one another;
+ * **Unqualified** -- the relative position is not qualified, i.e. all solutions apply.
It is possible to create expressions using the qualifiers, for example:
~~~~~
#### Exterior/Interior
It is not hard to define the interior and exterior of a circle. As is shown in the following diagram, the exterior is indicated by the sense of the binormal, that is to say the right side according to the sense of traversing the circle. The left side is therefore the interior (or "material").
-@image html /user_guides/modeling_algos/images/modeling_algos_image006.png "Exterior/Interior of a Circle"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image006.png "Exterior/Interior of a Circle"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image006.png,"Exterior/Interior of a Circle",220}
By extension, the interior of a line or any open curve is defined as the left side according to the passing direction, as shown in the following diagram:
-@image html /user_guides/modeling_algos/images/modeling_algos_image007.png "Exterior/Interior of a Line and a Curve"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image007.png "Exterior/Interior of a Line and a Curve"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image007.png,"Exterior/Interior of a Line and a Curve",220}
#### Orientation of a Line
It is sometimes necessary to define in advance the sense of travel along a line to be created. This sense will be from first to second argument.
The following figure shows a line, which is first tangent to circle C1 which is interior to the line, and then passes through point P1.
-@image html /user_guides/modeling_algos/images/modeling_algos_image008.png "An Oriented Line"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image008.png "An Oriented Line"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image008.png,"An Oriented Line",220}
#### Line tangent to two circles
**Example 1 Case 1**
-@image html /user_guides/modeling_algos/images/modeling_algos_image009.png "Both circles outside"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image009.png "Both circles outside"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image009.png,"Both circles outside",220}
Constraints:
Tangent and Exterior to C1.
**Example 1 Case 2**
-@image html /user_guides/modeling_algos/images/modeling_algos_image010.png "Both circles enclosed"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image010.png "Both circles enclosed"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image010.png,"Both circles enclosed",220}
Constraints:
Tangent and Including C1.
**Example 1 Case 3**
-@image html /user_guides/modeling_algos/images/modeling_algos_image011.png "C1 enclosed, C2 outside"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image011.png "C1 enclosed, C2 outside"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image011.png,"C1 enclosed and C2 outside",220}
Constraints:
Tangent and Including C1.
**Example 1 Case 4**
-@image html /user_guides/modeling_algos/images/modeling_algos_image012.png "C1 outside, C2 enclosed"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image012.png "C1 outside, C2 enclosed"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image012.png,"C1 outside and C2 enclosed",220}
Constraints:
Tangent and Exterior to C1.
Tangent and Including C2.
**Example 1 Case 5**
-@image html /user_guides/modeling_algos/images/modeling_algos_image013.png "With no qualifiers specified"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image013.png "With no qualifiers specified"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image013.png,"Without qualifiers",220}
Constraints:
Tangent and Undefined with respect to C1.
The following four diagrams show the four cases in using qualifiers in the creation of a circle.
**Example 2 Case 1**
-@image html /user_guides/modeling_algos/images/modeling_algos_image014.png "Both solutions outside"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image014.png "Both solutions outside"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image014.png,"Both solutions outside",220}
Constraints:
Tangent and Exterior to C1.
**Example 2 Case 2**
-@image html /user_guides/modeling_algos/images/modeling_algos_image015.png "C2 encompasses C1"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image015.png "C2 encompasses C1"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image015.png,"C2 encompasses C1",220}
Constraints:
Tangent and Exterior to C1.
~~~~~
**Example 2 Case 3**
-@image html /user_guides/modeling_algos/images/modeling_algos_image016.png "Solutions enclose C2"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image016.png "Solutions enclose C2"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image016.png,"Solutions enclose C2",220}
Constraints:
Tangent and Exterior to C1.
~~~~~
**Example 2 Case 4**
-@image html /user_guides/modeling_algos/images/modeling_algos_image017.png "Solutions enclose C1"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image017.png "Solutions enclose C1"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image017.png,"Solutions enclose C1",220}
Constraints:
Tangent and Enclosing C1.
A case in point is the intersection of two fillets at a corner. If the radius of the fillet on one edge is different from that of the fillet on another, it becomes impossible to sew together all the edges of the resulting surfaces. This leaves a gap in the overall surface of the object which you are constructing.
-@figure{/user_guides/modeling_algos/images/modeling_algos_image059.png,"Intersecting filleted edges with differing radiuses"}
+@figure{/user_guides/modeling_algos/images/modeling_algos_image059.png,"Intersecting filleted edges with differing radiuses",220}
These algorithms allow you to fill this gap from two, three or four curves. This can be done with or without constraints, and the resulting surface will be either a Bezier or a BSpline surface in one of a range of filling styles.
The enumerations *FillingStyle* specify the styles used to build the surface. These include:
- * *Stretch* - the style with the flattest patches
- * *Coons* - a rounded style with less depth than *Curved*
- * *Curved* - the style with the most rounded patches.
+ * *Stretch* -- the style with the flattest patches
+ * *Coons* -- a rounded style with less depth than *Curved*
+ * *Curved* -- the style with the most rounded patches.
-@image html /user_guides/modeling_algos/images/modeling_algos_image018.png "Intersecting filleted edges with different radii leave a gap, is filled by a surface"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image018.png "Intersecting filleted edges with different radii leave a gap, is filled by a surface"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image018.png,"Intersecting filleted edges with different radii leave a gap filled by a surface",274}
@subsubsection occt_modalg_2_5_5 Plate surfaces
The surface is built using a variational spline algorithm. It uses the principle of deformation of a thin plate by localised mechanical forces. If not already given in the input, an initial surface is calculated. This corresponds to the plate prior
to deformation. Then, the algorithm is called to calculate the final surface. It looks for a solution satisfying constraints and minimizing energy input.
-@figure{/user_guides/modeling_algos/images/modeling_algos_image061.png,"Surface generated from two curves and a point"}
+@figure{/user_guides/modeling_algos/images/modeling_algos_image061.png,"Surface generated from two curves and a point",360}
The package *GeomPlate* provides the following services for creating surfaces respecting curve and point constraints:
The class *MakeApprox* allows converting a *GeomPlate* surface into a *Geom_BSplineSurface*.
-@figure{/user_guides/modeling_algos/images/modeling_algos_image060.png,"Surface generated from four curves and a point"}
+@figure{/user_guides/modeling_algos/images/modeling_algos_image060.png,"Surface generated from four curves and a point",360}
Let us create a Plate surface and approximate it from a polyline as a curve constraint and a point constraint
// create a face corresponding to the approximated Plate
Surface
Standard_Real Umin, Umax, Vmin, Vmax;
-PSurf-Bounds( Umin, Umax, Vmin, Vmax);
+PSurf->Bounds( Umin, Umax, Vmin, Vmax);
BRepBuilderAPI_MakeFace MF(Surf,Umin, Umax, Vmin, Vmax);
~~~~~
*Geom2dAPI_ProjectPointOnCurve* allows calculation of all normals projected from a point (*gp_Pnt2d*) onto a geometric curve (*Geom2d_Curve*). The calculation may be restricted to a given domain.
-@image html /user_guides/modeling_algos/images/modeling_algos_image020.png "Normals from a point to a curve"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image020.png "Normals from a point to a curve"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image020.png,"Normals from a point to a curve",320}
The curve does not have to be a *Geom2d_TrimmedCurve*. The algorithm will function with any class inheriting *Geom2d_Curve*.
The class *GeomAPI_ProjectPointOnSurf* allows calculation of all normals projected from a point from *gp_Pnt* onto a geometric surface from *Geom_Surface*.
-@image html /user_guides/modeling_algos/images/modeling_algos_image021.png "Projection of normals from a point to a surface"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image021.png "Projection of normals from a point to a surface"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image021.png,"Projection of normals from a point to a surface",360}
Note that the surface does not have to be of *Geom_RectangularTrimmedSurface* type.
The algorithm will function with any class inheriting *Geom_Surface*.
Handle(Geom_Curve) C3d = GeomAPI::To3d(C2d, Pln);
~~~~~
+
+@section occt_modalg_2_topo_tools Topological Tools
+
+Open CASCADE Technology topological tools provide algorithms to
+ * Create wires from edges;
+ * Create faces from wires;
+ * Compute state of the shape relatively other shape;
+ * Orient shapes in container;
+ * Create new shapes from the existing ones;
+ * Build PCurves of edges on the faces;
+ * Check the validity of the shapes;
+ * Take the point in the face;
+ * Get the normal direction for the face.
+
+
+@subsection occt_modalg_2_topo_tools_1 Creation of the faces from wireframe model
+
+It is possible to create the planar faces from the arbitrary set of planar edges randomly located in 3D space.
+This feature might be useful if you need for instance to restore the shape from the wireframe model:
+<table align="center">
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_image062.png,"Wireframe model",160}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_image063.png,"Faces of the model",160}</td>
+</tr>
+</table>
+
+To make the faces from edges it is, firstly, necessary to create planar wires from the given edges and than create planar faces from each wire.
+The static methods *BOPAlgo_Tools::EdgesToWires* and *BOPAlgo_Tools::WiresToFaces* can be used for that:
+~~~~~
+TopoDS_Shape anEdges = ...; /* The input edges */
+Standard_Real anAngTol = 1.e-8; /* The angular tolerance for distinguishing the planes in which the wires are located */
+Standard_Boolean bShared = Standard_False; /* Defines whether the edges are shared or not */
+//
+TopoDS_Shape aWires; /* resulting wires */
+Standard_Integer iErr = BOPAlgo_Tools::EdgesToWires(anEdges, aWires, bShared, anAngTol);
+if (iErr) {
+ cout << "Error: Unable to build wires from given edges\n";
+ return;
+}
+//
+TopoDS_Shape aFaces; /* resulting faces */
+Standard_Boolean bDone = BOPAlgo_Tools::WiresToFaces(aWires, aFaces, anAngTol);
+if (!bDone) {
+ cout << "Error: Unable to build faces from wires\n";
+ return;
+}
+~~~~~
+
+These methods can also be used separately:
+ * *BOPAlgo_Tools::EdgesToWires* allows creating planar wires from edges.
+The input edges may be not shared, but the output wires will be sharing the coinciding vertices and edges. For this the intersection of the edges is performed.
+Although, it is possible to skip the intersection stage (if the input edges are already shared) by passing the corresponding flag into the method.
+The input edges are expected to be planar, but the method does not check it. Thus, if the input edges are not planar, the output wires will also be not planar.
+In general, the output wires are non-manifold and may contain free vertices, as well as multi-connected vertices.
+ * *BOPAlgo_Tools::WiresToFaces* allows creating planar faces from the planar wires.
+In general, the input wires are non-manifold and may be not closed, but should share the coinciding parts.
+The wires located in the same plane and completely included into other wires will create holes in the faces built from outer wires:
+
+<table align="center">
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_image064.png,"Wireframe model",160}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_image065.png,"Two faces (red face has a hole)",160}</td>
+</tr>
+</table>
+
+
+@subsection occt_modalg_2_topo_tools_2 Classification of the shapes
+
+The following methods allow classifying the different shapes relatively other shapes:
+ * The variety of the *BOPTools_AlgoTools::ComputState* methods classify the vertex/edge/face relatively solid;
+ * *BOPTools_AlgoTools::IsHole* classifies wire relatively face;
+ * *IntTools_Tools::ClassifyPointByFace* classifies point relatively face.
+
+@subsection occt_modalg_2_topo_tools_3 Orientation of the shapes in the container
+
+The following methods allow reorienting shapes in the containers:
+ * *BOPTools_AlgoTools::OrientEdgesOnWire* correctly orients edges on the wire;
+ * *BOPTools_AlgoTools::OrientFacesOnShell* correctly orients faces on the shell.
+
+@subsection occt_modalg_2_topo_tools_4 Making new shapes
+
+The following methods allow creating new shapes from the existing ones:
+ * The variety of the *BOPTools_AlgoTools::MakeNewVertex* creates the new vertices from other vertices and edges;
+ * *BOPTools_AlgoTools::MakeSplitEdge* splits the edge by the given parameters.
+
+@subsection occt_modalg_2_topo_tools_5 Building PCurves
+
+The following methods allow building PCurves of edges on faces:
+ * *BOPTools_AlgoTools::BuildPCurveForEdgeOnFace* computes PCurve for the edge on the face;
+ * *BOPTools_AlgoTools::BuildPCurveForEdgeOnPlane* and *BOPTools_AlgoTools::BuildPCurveForEdgesOnPlane* allow building PCurves for edges on the planar face;
+ * *BOPTools_AlgoTools::AttachExistingPCurve* takes PCurve on the face from one edge and attach this PCurve to other edge coinciding with the first one.
+
+@subsection occt_modalg_2_topo_tools_6 Checking the validity of the shapes
+
+The following methods allow checking the validity of the shapes:
+ * *BOPTools_AlgoTools::IsMicroEdge* detects the small edges;
+ * *BOPTools_AlgoTools::ComputeTolerance* computes the correct tolerance of the edge on the face;
+ * *BOPTools_AlgoTools::CorrectShapeTolerances* and *BOPTools_AlgoTools::CorrectTolerances* allow correcting the tolerances of the sub-shapes.
+ * *BRepLib::FindValidRange* finds a range of 3d curve of the edge not covered by tolerance spheres of vertices.
+
+@subsection occt_modalg_2_topo_tools_7 Taking a point inside the face
+
+The following methods allow taking a point located inside the face:
+ * The variety of the *BOPTools_AlgoTools3D::PointNearEdge* allows getting a point inside the face located near the edge;
+ * *BOPTools_AlgoTools3D::PointInFace* allows getting a point inside the face.
+
+@subsection occt_modalg_2_topo_tools_8 Getting normal for the face
+
+The following methods allow getting the normal direction for the face/surface:
+ * *BOPTools_AlgoTools3D::GetNormalToSurface* computes the normal direction for the surface in the given point defined by UV parameters;
+ * *BOPTools_AlgoTools3D::GetNormalToFaceOnEdge* computes the normal direction for the face in the point located on the edge of the face;
+ * *BOPTools_AlgoTools3D::GetApproxNormalToFaceOnEdge* computes the normal direction for the face in the point located near the edge of the face.
+
+
+
@section occt_modalg_3a The Topology API
The Topology API of Open CASCADE Technology (**OCCT**) includes the following six packages:
TopoDS_Edge E = ME;
~~~~~
+
+@subsection occt_modalg_hist History support
+
+All topological API algorithms support the history of shape modifications (or just History) for their arguments.
+Generally, the history is available for the following types of sub-shapes of input shapes:
+* Vertex;
+* Edge;
+* Face.
+
+Some algorithms also support the history for Solids.
+
+The history information consists of the following information:
+* Information about Deleted shapes;
+* Information about Modified shapes;
+* Information about Generated shapes.
+
+The History is filled basing on the result of the operation. History cannot return any shapes not contained in the result.
+If the result of the operation is an empty shape, all input shapes will be considered as Deleted and none will have Modified and Generated shapes.
+
+The history information can be accessed by the API methods:
+* *Standard_Boolean IsDeleted(const TopoDS_Shape& theS)* - to check if the shape has been Deleted during the operation;
+* *const TopTools_ListOfShape& Modified(const TopoDS_Shape& theS)* - to get the shapes Modified from the given shape;
+* *const TopTools_ListOfShape& Generated(const TopoDS_Shape& theS)* - to get the shapes Generated from the given shape.
+
+@subsubsection occt_modalg_hist_del Deleted shapes
+
+The shape is considered as Deleted during the operation if all of the following conditions are met:
+* The shape is a part of the argument shapes of the operation;
+* The result shape does not contain the shape itself;
+* The result shape does not contain any of the splits of the shape.
+
+For example, in the CUT operation between two intersecting solids all vertices/edges/faces located completely inside the Tool solid will be Deleted during the operation.
+
+@subsubsection occt_modalg_hist_mod Modified shapes
+
+The shape is considered as Modified during the operation if the result shape contains the splits of the shape, not the shape itself. The shape can be modified only into the shapes with the same dimension.
+The splits of the shape contained in the result shape are Modified from the shape.
+The Modified shapes are created from the sub-shapes of the input shapes and, generally, repeat their geometry.
+
+The list of Modified elements will contain only those contributing to the result of the operation. If the list is empty, the shape has not been modified and it is necessary to check if it has been Deleted.
+
+For example, after translation of the shape in any direction all its sub-shapes will be modified into their translated copies.
+
+@subsubsection occt_modalg_hist_gen Generated shapes
+
+The shapes contained in the result shape are considered as Generated from the input shape if they were produced during the operation and have a different dimension from the shapes from which they were created.
+
+The list of Generated elements will contain only those included in the result of the operation. If the list is empty, no new shapes have been Generated from the shape.
+
+For example, extrusion of the edge in some direction will create a face. This face will be generated from the edge.
+
+@subsubsection occt_modalg_hist_tool BRepTools_History
+
+*BRepTools_History* is the general History tool intended for unification of the histories of different algorithms.
+
+*BRepTools_History* can be created from any algorithm supporting the standard history methods *(IsDeleted(), Modified()* and *Generated())*:
+~~~~
+// The arguments of the operation
+TopoDS_Shape aS = ...;
+
+// Perform transformation on the shape
+gp_Trsf aTrsf;
+aTrsf.SetTranslationPart(gp_Vec(0, 0, 1));
+BRepBuilderAPI_Transform aTransformer(aS, aTrsf); // Transformation API algorithm
+const TopoDS_Shape& aRes = aTransformer.Shape();
+
+// Create the translation history object
+TopTools_ListOfShape anArguments;
+anArguments.Append(aS);
+BRepTools_History aHistory(anArguments, aTransformer);
+~~~~
+
+*BRepTools_History* also allows merging histories. Thus, if you have two or more subsequent operations you can get one final history combined from histories of these operations:
+
+~~~~
+Handle(BRepTools_History) aHist1 = ...; // History of first operation
+Handle(BRepTools_History) aHist2 = ...; // History of second operation
+~~~~
+
+It is possible to merge the second history into the first one:
+~~~~
+aHist1->Merge(aHist2);
+~~~~
+
+Or create the new history keeping the two histories unmodified:
+~~~~
+Handle(BRepTools_History) aResHistory = new BRepTools_History;
+aResHistory->Merge(aHist1);
+aResHistory->Merge(aHist2);
+~~~~
+
+The possibilities of Merging histories and history creation from the API algorithms allow providing easy History support for the new algorithms.
+
+@subsubsection occt_modalg_hist_draw DRAW history support
+
+DRAW History support for the algorithms is provided by three basic commands:
+* *isdeleted*;
+* *modified*;
+* *generated*.
+
+For more information on the Draw History mechanism, refer to the corresponding chapter in the Draw users guide - @ref occt_draw_hist "History commands".
+
+
@section occt_modalg_3 Standard Topological Objects
The following standard topological objects can be created:
- * Vertices
- * Edges
- * Faces
- * Wires
- * Polygonal wires
- * Shells
+ * Vertices;
+ * Edges;
+ * Faces;
+ * Wires;
+ * Polygonal wires;
+ * Shells;
* Solids.
There are two root classes for their construction and modification:
where C is the domain of the edge; V1 is the first vertex oriented FORWARD; V2 is the second vertex oriented REVERSED; p1 and p2 are the parameters for the vertices V1 and V2 on the curve. The default tolerance is associated with this edge.
-@image html /user_guides/modeling_algos/images/modeling_algos_image022.png "Basic Edge Construction"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image022.png "Basic Edge Construction"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image022.png,"Basic Edge Construction",220}
The following rules apply to the arguments:
The figure below illustrates two special cases, a semi-infinite edge and an edge on a periodic curve.
-@image html /user_guides/modeling_algos/images/modeling_algos_image023.png "Infinite and Periodic Edges"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image023.png "Infinite and Periodic Edges"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image023.png,"Infinite and Periodic Edges",220}
@subsubsection occt_modalg_3_2_2 Supplementary edge construction methods
The *Error* method returns a term of the *BRepBuilderAPI_EdgeError* enumeration. It can be used to analyze the error when *IsDone* method returns False. The terms are:
- * **EdgeDone** - No error occurred, *IsDone* returns True.
- * **PointProjectionFailed** - No parameters were given, but the projection of the 3D points on the curve failed. This happens if the point distance to the curve is greater than the precision.
- * **ParameterOutOfRange** - The given parameters are not in the range *C->FirstParameter()*, *C->LastParameter()*
- * **DifferentPointsOnClosedCurve** - The two vertices or points have different locations but they are the extremities of a closed curve.
- * **PointWithInfiniteParameter** - A finite coordinate point was associated with an infinite parameter (see the Precision package for a definition of infinite values).
- * **DifferentsPointAndParameter** - The distance of the 3D point and the point evaluated on the curve with the parameter is greater than the precision.
- * **LineThroughIdenticPoints** - Two identical points were given to define a line (construction of an edge without curve), *gp::Resolution* is used to test confusion .
+ * **EdgeDone** -- No error occurred, *IsDone* returns True.
+ * **PointProjectionFailed** -- No parameters were given, but the projection of the 3D points on the curve failed. This happens if the point distance to the curve is greater than the precision.
+ * **ParameterOutOfRange** -- The given parameters are not in the range *C->FirstParameter()*, *C->LastParameter()*
+ * **DifferentPointsOnClosedCurve** -- The two vertices or points have different locations but they are the extremities of a closed curve.
+ * **PointWithInfiniteParameter** -- A finite coordinate point was associated with an infinite parameter (see the Precision package for a definition of infinite values).
+ * **DifferentsPointAndParameter** -- The distance of the 3D point and the point evaluated on the curve with the parameter is greater than the precision.
+ * **LineThroughIdenticPoints** -- Two identical points were given to define a line (construction of an edge without curve), *gp::Resolution* is used to test confusion .
The following example creates a rectangle centered on the origin of dimensions H, L with fillets of radius R. The edges and the vertices are stored in the arrays *theEdges* and *theVertices*. We use class *Array1OfShape* (i.e. not arrays of edges or vertices). See the image below.
-@image html /user_guides/modeling_algos/images/modeling_algos_image024.png "Creating a Wire"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image024.png "Creating a Wire"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image024.png,"Creating a Wire",360}
~~~~~
#include <BRepBuilderAPI_MakeEdge.hxx>
TopoDS_Face F = BRepBuilderAPI_MakeFace(S,umin,umax,vmin,vmax);
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image025.png "Basic Face Construction"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image025.png "Basic Face Construction"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image025.png,"Basic Face Construction",360}
To make a face from the natural boundary of a surface, the parameters are not required:
The *Error* method returns an error status, which is a term from the *BRepBuilderAPI_FaceError* enumeration.
-* *FaceDone* - no error occurred.
-* *NoFace* - no initialization of the algorithm; an empty constructor was used.
-* *NotPlanar* - no surface was given and the wire was not planar.
-* *CurveProjectionFailed* - no curve was found in the parametric space of the surface for an edge.
-* *ParametersOutOfRange* - the parameters *umin, umax, vmin, vmax* are out of the surface.
+* *FaceDone* -- no error occurred.
+* *NoFace* -- no initialization of the algorithm; an empty constructor was used.
+* *NotPlanar* -- no surface was given and the wire was not planar.
+* *CurveProjectionFailed* -- no curve was found in the parametric space of the surface for an edge.
+* *ParametersOutOfRange* -- the parameters *umin, umax, vmin, vmax* are out of the surface.
@subsection occt_modalg_3_6 Wire
The wire is a composite shape built not from a geometry, but by the assembly of edges. *BRepBuilderAPI_MakeWire* class can build a wire from one or more edges or connect new edges to an existing wire.
BRepBuilderAPI_MakeWire class can return the last edge added to the wire (Edge method). This edge can be different from the original edge if it was copied.
The Error method returns a term of the *BRepBuilderAPI_WireError* enumeration:
-*WireDone* - no error occurred.
-*EmptyWire* - no initialization of the algorithm, an empty constructor was used.
-*DisconnectedWire* - the last added edge was not connected to the wire.
-*NonManifoldWire* - the wire with some singularity.
+*WireDone* -- no error occurred.
+*EmptyWire* -- no initialization of the algorithm, an empty constructor was used.
+*DisconnectedWire* -- the last added edge was not connected to the wire.
+*NonManifoldWire* -- the wire with some singularity.
@subsection occt_modalg_3_7 Shell
The shell is a composite shape built not from a geometry, but by the assembly of faces.
The four methods to build a box are shown in the figure:
-@image html /user_guides/modeling_algos/images/modeling_algos_image026.png "Making Boxes"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image026.png "Making Boxes"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image026.png,"Making Boxes",420}
@subsubsection occt_modalg_4_1_2 Wedge
*BRepPrimAPI_MakeWedge* class allows building a wedge, which is a slanted box, i.e. a box with angles. The wedge is constructed in much the same way as a box i.e. from three dimensions dx,dy,dz plus arguments or from an axis system, three dimensions, and arguments.
The first method is a particular case of the second with *xmin = 0, xmax = ltx, zmin = 0, zmax = dz*.
To make a centered pyramid you can use *xmin = xmax = dx / 2, zmin = zmax = dz / 2*.
-@image html /user_guides/modeling_algos/images/modeling_algos_image027.png "Making Wedges"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image027.png "Making Wedges"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image027.png,"Making Wedges",420}
@subsubsection occt_modalg_4_1_3 Rotation object
*BRepPrimAPI_MakeOneAxis* is a deferred class used as a root class for all classes constructing rotational primitives. Rotational primitives are created by rotating a curve around an axis. They cover the cylinder, the cone, the sphere, the torus, and the revolution, which provides all other curves.
The result of the OneAxis construction is a Solid, a Shell, or a Face. The face is the face covering the rotational surface. Remember that you will not use the OneAxis directly but one of the derived classes, which provide improved constructions. The following figure illustrates the OneAxis arguments.
-@image html /user_guides/modeling_algos/images/modeling_algos_image028.png "MakeOneAxis arguments"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image028.png "MakeOneAxis arguments"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image028.png,"MakeOneAxis arguments",360}
@subsubsection occt_modalg_4_1_4 Cylinder
*BRepPrimAPI_MakeCylinder* class allows creating cylindrical primitives. A cylinder is created either in the default coordinate system or in a given coordinate system *gp_Ax2*. There are two constructions:
TopoDS_Face F =
BRepPrimAPI_MakeCylinder(axes,R,DY,PI/2.);
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image029.png "Cylinder"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image029.png "Cylinder"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image029.png,"Cylinder",360}
@subsubsection occt_modalg_4_1_5 Cone
*BRepPrimAPI_MakeCone* class allows creating conical primitives. Like a cylinder, a cone is created either in the default coordinate system or in a given coordinate system (gp_Ax2). There are two constructions:
TopoDS_Solid S = BRepPrimAPI_MakeCone(R1,R2,H);
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image030.png "Cone"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image030.png "Cone"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image030.png,"Cone",360}
@subsubsection occt_modalg_4_1_6 Sphere
*BRepPrimAPI_MakeSphere* class allows creating spherical primitives. Like a cylinder, a sphere is created either in the default coordinate system or in a given coordinate system *gp_Ax2*. There are four constructions:
- * From a radius - builds a full sphere.
- * From a radius and an angle - builds a lune (digon).
- * From a radius and two angles - builds a wraparound spherical segment between two latitudes. The angles *a1* and *a2* must follow the relation: <i>PI/2 <= a1 < a2 <= PI/2 </i>.
- * From a radius and three angles - a combination of two previous methods builds a portion of spherical segment.
+ * From a radius -- builds a full sphere.
+ * From a radius and an angle -- builds a lune (digon).
+ * From a radius and two angles -- builds a wraparound spherical segment between two latitudes. The angles *a1* and *a2* must follow the relation: <i>PI/2 <= a1 < a2 <= PI/2 </i>.
+ * From a radius and three angles -- a combination of two previous methods builds a portion of spherical segment.
The following code builds four spheres from a radius and three angles.
Note that we could equally well choose to create Shells instead of Solids.
-@image html /user_guides/modeling_algos/images/modeling_algos_image031.png "Examples of Spheres"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image031.png "Examples of Spheres"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image031.png,"Examples of Spheres",420}
@subsubsection occt_modalg_4_1_7 Torus
*BRepPrimAPI_MakeTorus* class allows creating toroidal primitives. Like the other primitives, a torus is created either in the default coordinate system or in a given coordinate system *gp_Ax2*. There are four constructions similar to the sphere constructions:
- * Two radii - builds a full torus.
- * Two radii and an angle - builds an angular torus segment.
- * Two radii and two angles - builds a wraparound torus segment between two radial planes. The angles a1, a2 must follow the relation 0 < a2 - a1 < 2*PI.
- * Two radii and three angles - a combination of two previous methods builds a portion of torus segment.
+ * Two radii -- builds a full torus.
+ * Two radii and an angle -- builds an angular torus segment.
+ * Two radii and two angles -- builds a wraparound torus segment between two radial planes. The angles a1, a2 must follow the relation 0 < a2 - a1 < 2*PI.
+ * Two radii and three angles -- a combination of two previous methods builds a portion of torus segment.
-@image html /user_guides/modeling_algos/images/modeling_algos_image032.png "Examples of Tori"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image032.png "Examples of Tori"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image032.png,"Examples of Tori",420}
The following code builds four toroidal shells from two radii and three angles.
It is forbidden to sweep Solids and Composite Solids. A Compound generates a Compound with the sweep of all its elements.
-@image html /user_guides/modeling_algos/images/modeling_algos_image033.png "Generating a sweep"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image033.png "Generating a sweep"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image033.png,"Generating a sweep",360}
*BRepPrimAPI_MakeSweep class* is a deferred class used as a root of the the following sweep classes:
-* *BRepPrimAPI_MakePrism* - produces a linear sweep
-* *BRepPrimAPI_MakeRevol* - produces a rotational sweep
-* *BRepPrimAPI_MakePipe* - produces a general sweep.
+* *BRepPrimAPI_MakePrism* -- produces a linear sweep
+* *BRepPrimAPI_MakeRevol* -- produces a rotational sweep
+* *BRepPrimAPI_MakePipe* -- produces a general sweep.
@subsubsection occt_modalg_4_2_2 Prism
// semi-infinite
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image034.png "Finite, infinite, and semi-infinite prisms"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image034.png "Finite, infinite, and semi-infinite prisms"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image034.png,"Finite, infinite, and semi-infinite prisms",420}
@subsubsection occt_modalg_4_2_3 Rotational Sweep
*BRepPrimAPI_MakeRevol* class allows creating a rotational sweep from a shape, an axis (gp_Ax1), and an angle. The angle has a default value of 2*PI which means a closed revolution.
TopoDS_Solid R2 = BRepPrimAPI_MakeRevol(F,axis,ang);
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image035.png "Full and partial rotation"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image035.png "Full and partial rotation"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image035.png,"Full and partial rotation",420}
@section occt_modalg_5 Boolean Operations
-Boolean operations are used to create new shapes from the combinations of two shapes.
+Boolean operations are used to create new shapes from the combinations of two groups of shapes.
| Operation | Result |
| :---- | :------ |
| Common | all points in S1 and S2 |
| Cut S1 by S2| all points in S1 and not in S2 |
-@image html /user_guides/modeling_algos/images/modeling_algos_image036.png "Boolean Operations"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image036.png "Boolean Operations"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image036.png,"Boolean Operations",420}
From the viewpoint of Topology these are topological operations followed by blending (putting fillets onto edges created after the topological operation).
*BRepAlgoAPI_Section* performs the section, described as a *TopoDS_Compound* made of *TopoDS_Edge*.
-@image html /user_guides/modeling_algos/images/modeling_algos_image037.png "Section operation"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image037.png "Section operation"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image037.png,"Section operation",220}
~~~~~
TopoDS_Shape A = ..., TopoDS_ShapeB = ...;
A fillet description contains an edge and a radius. The edge must be shared by two faces. The fillet is automatically extended to all edges in a smooth continuity with the original edge. It is not an error to add a fillet twice, the last description holds.
-@image html /user_guides/modeling_algos/images/modeling_algos_image038.png "Filleting two edges using radii r1 and r2."
-@image latex /user_guides/modeling_algos/images/modeling_algos_image038.png "Filleting two edges using radii r1 and r2."
+@figure{/user_guides/modeling_algos/images/modeling_algos_image038.png,"Filleting two edges using radii r1 and r2.",360}
In the following example a filleted box with dimensions a,b,c and radius r is created.
}
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image039.png "Fillet with constant radius"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image039.png "Fillet with constant radius"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image039.png,"Fillet with constant radius",360}
#### Changing radius
}
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image040.png "Fillet with changing radius"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image040.png "Fillet with changing radius"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image040.png,"Fillet with changing radius",360}
@subsection occt_modalg_6_1_2 Chamfer
Add(d1, d2, E, F) with d1 on the face F.
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image041.png "Chamfer"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image041.png "Chamfer"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image041.png,"Chamfer",360}
@subsection occt_modalg_6_1_3 Fillet on a planar face
* Creation of tapered shapes using draft angles;
* Creation of sweeps.
-@subsection occt_modalg_7_1 Shelling
+@subsection occt_modalg_7_1 Offset computation
+
+Offset computation can be performed using *BRepOffsetAPI_MakeOffsetShape*. This class provides API to the two different offset algorithms:
+
+Offset algorithm based on computation of the analytical continuation. Meaning of the parameters can be found in *BRepOffsetAPI_MakeOffsetShape::PerformByJoin* method description. The list below demonstrates principal scheme of this algorithm:
+
+* At the first step, the offsets are computed.
+* After this, the analytical continuations are computed for each offset.
+* Pairwise intersection is computed according to the original topological information (sharing, number of neighbors, etc.).
+* The offset shape is assembled.
+
+The second algorithm is based on the fact that the offset computation for a single face without continuation can always be built. The list below shows simple offset algorithm:
+* Each surface is mapped to its geometric offset surface.
+* For each edge, pcurves are mapped to the same pcurves on offset surfaces.
+* For each edge, 3d curve is constructed by re-approximation of pcurve on the first offset face.
+* Position of each vertex in a result shell is computed as average point of all ends of edges sharing that vertex.
+* Tolerances are updated according to the resulting geometry.
+The possible drawback of the simple algorithm is that it leads, in general case, to tolerance increasing. The tolerances have to grow in order to cover the gaps between the neighbor faces in the output. It should be noted that the actual tolerance growth depends on the offset distance and the quality of joints between the input faces. Anyway the good input shell (smooth connections between adjacent faces) will lead to good result.
+
+The snippets below show usage examples:
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
+ BRepOffsetAPI_MakeOffsetShape OffsetMaker1;
+ // Computes offset shape using analytical continuation mechanism.
+ OffsetMaker1.PerformByJoin(Shape, OffsetValue, Tolerance);
+ if (OffsetMaker1.IsDone())
+ NewShape = OffsetMaker1.Shape();
+
+ BRepOffsetAPI_MakeOffsetShape OffsetMaker2;
+ // Computes offset shape using simple algorithm.
+ OffsetMaker2.PerformBySimple(Shape, OffsetValue);
+ if (OffsetMaker2.IsDone())
+ NewShape = OffsetMaker2.Shape();
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Shelling is used to offset given faces of a solid by a specific value. It rounds or intersects adjacent faces along its edges depending on the convexity of the edge.
+@subsection occt_modalg_7_2 Shelling
-The constructor *BRepOffsetAPI_MakeThickSolid* shelling operator takes the solid, the list of faces to remove and an offset value as input.
+Shelling is used to offset given faces of a solid by a specific value. It rounds or intersects adjacent faces along its edges depending on the convexity of the edge.
+The MakeThickSolidByJoin method of the *BRepOffsetAPI_MakeThickSolid* takes the solid, the list of faces to remove and an offset value as input.
~~~~~
TopoDS_Solid SolidInitial = ...;
LCF.Append(SF);
}
-Result = BRepOffsetAPI_MakeThickSolid (SolidInitial,
- LCF,
- Of,
- Tol);
+BRepOffsetAPI_MakeThickSolid SolidMaker;
+SolidMaker.MakeThickSolidByJoin(SolidInitial,
+ LCF,
+ Of,
+ Tol);
+if (SolidMaker.IsDone())
+ Result = SolidMaker.Shape();
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image042.png "Shelling"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image042.png "Shelling"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image042.png,"Shelling",420}
+
+Also it is possible to create solid between shell, offset shell. This functionality can be called using *BRepOffsetAPI_MakeThickSolid::MakeThickSolidBySimple* method. The code below shows usage example:
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.cpp}
+ BRepOffsetAPI_MakeThickSolid SolidMaker;
+ SolidMaker.MakeThickSolidBySimple(Shell, OffsetValue);
+ if (myDone.IsDone())
+ Solid = SolidMaker.Shape();
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-@subsection occt_modalg_7_2 Draft Angle
+@subsection occt_modalg_7_3 Draft Angle
*BRepOffsetAPI_DraftAngle* class allows modifying a shape by applying draft angles to its planar, cylindrical and conical faces.
}
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image043.png "DraftAngle"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image043.png "DraftAngle"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image043.png,"DraftAngle",420}
-@subsection occt_modalg_7_3 Pipe Constructor
+@subsection occt_modalg_7_4 Pipe Constructor
*BRepOffsetAPI_MakePipe* class allows creating a pipe from a Spine, which is a Wire and a Profile which is a Shape. This implementation is limited to spines with smooth transitions, sharp transitions are precessed by *BRepOffsetAPI_MakePipeShell*. To be more precise the continuity must be G1, which means that the tangent must have the same direction, though not necessarily the same magnitude, at neighboring edges.
TopoDS_Shape Pipe = BRepOffsetAPI_MakePipe(Spine,Profile);
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image044.png "Example of a Pipe"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image044.png "Example of a Pipe"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image044.png,"Example of a Pipe",320}
-@subsection occt_modalg_7_4 Evolved Solid
+@subsection occt_modalg_7_5 Evolved Solid
*BRepOffsetAPI_MakeEvolved* class allows creating an evolved solid from a Spine (planar face or wire) and a profile (wire).
Sewing allows creation of connected topology (shells and wires) from a set of separate topological elements (faces and edges). For example, Sewing can be used to create of shell from a compound of separate faces.
-@image html /user_guides/modeling_algos/images/modeling_algos_image045.png "Shapes with partially shared edges"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image045.png "Shapes with partially shared edges"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image045.png,"Shapes with partially shared edges",320}
It is important to distinguish between sewing and other procedures, which modify the geometry, such as filling holes or gaps, gluing, bending curves and surfaces, etc.
}
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image047.png "Fusion with MakePrism"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image047.png "Fusion with MakePrism"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image047.png,"Fusion with MakePrism",320}
-@image html /user_guides/modeling_algos/images/modeling_algos_image048.png "Creating a prism between two faces with Perform(From, Until)"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image048.png "Creating a prism between two faces with Perform(From, Until)"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image048.png,"Creating a prism between two faces with Perform()",320}
@subsubsection occt_modalg_9_1_2 Draft Prism
TopoDS_Shape res1 = MKDP.Shape();
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image049.png "A tapered prism"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image049.png "A tapered prism"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image049.png,"A tapered prism",320}
@subsubsection occt_modalg_9_1_3 Revolution
TopoDS_Shape res1 = MKPipe.Shape();
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image050.png "Pipe depression"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image050.png "Pipe depression"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image050.png,"Pipe depression",240}
@subsection occt_modalg_9_2 Mechanical Features
Mechanical features include ribs, protrusions and grooves (or slots), depressions along planar (linear) surfaces or revolution surfaces.
-The semantics of mechanical features is built around giving thickness to a contour. This thickness can either be symmetrical - on one side of the contour - or dissymmetrical - on both sides. As in the semantics of form features, the thickness is defined by construction of shapes in specific contexts.
+The semantics of mechanical features is built around giving thickness to a contour. This thickness can either be symmetrical -- on one side of the contour -- or dissymmetrical -- on both sides. As in the semantics of form features, the thickness is defined by construction of shapes in specific contexts.
The development contexts differ, however, in the case of mechanical features.
Here they include extrusion:
TopoDS_Shape res = aform.Shape();
~~~~~
-@image html /user_guides/modeling_algos/images/modeling_algos_image051.png "Creating a rib"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image051.png "Creating a rib"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image051.png,"Creating a rib",240}
@subsubsection occt_modalg_9_2_3 Gluer
The class is created or initialized from a shape (the basic shape).
Three Add methods are available:
-* *Add(Wire, Face)* - adds a new wire on a face of the basic shape.
-* *Add(Edge, Face)* - adds a new edge on a face of the basic shape.
-* *Add(EdgeNew, EdgeOld)* - adds a new edge on an existing one (the old edge must contain the new edge).
+* *Add(Wire, Face)* -- adds a new wire on a face of the basic shape.
+* *Add(Edge, Face)* -- adds a new edge on a face of the basic shape.
+* *Add(EdgeNew, EdgeOld)* -- adds a new edge on an existing one (the old edge must contain the new edge).
**Note** The added wires and edges must define closed wires on faces or wires located between two existing edges. Existing edges must not be intersected.
However, there some restrictions in HLR use:
* Points are not processed;
- * Z-clipping planes are not used;
* Infinite faces or lines are not processed.
-@image html /user_guides/modeling_algos/images/modeling_algos_image052.png "Sharp, smooth and sewn edges in a simple screw shape"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image052.png "Sharp, smooth and sewn edges in a simple screw shape"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image052.png,"Sharp, smooth and sewn edges in a simple screw shape",320}
-@image html /user_guides/modeling_algos/images/modeling_algos_image053.png "Outline edges and isoparameters in the same shape"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image053.png "Outline edges and isoparameters in the same shape"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image053.png,"Outline edges and isoparameters in the same shape",320}
-@image html /user_guides/modeling_algos/images/modeling_algos_image054.png "A simple screw shape seen with shading"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image054.png "A simple screw shape seen with shading"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image054.png,"A simple screw shape seen with shading",320}
-@image html /user_guides/modeling_algos/images/modeling_algos_image055.png "An extraction showing hidden sharp edges"
-@image latex /user_guides/modeling_algos/images/modeling_algos_image055.png "An extraction showing hidden sharp edges"
+@figure{/user_guides/modeling_algos/images/modeling_algos_image055.png,"An extraction showing hidden sharp edges",320}
The following services are related to Hidden Lines Removal :
The algorithm of shape triangulation is provided by the functionality of *BRepMesh_IncrementalMesh* class, which adds a triangulation of the shape to its topological data structure. This triangulation is used to visualize the shape in shaded mode.
~~~~~
-const Standard_Real aRadius = 10.0;
-const Standard_Real aHeight = 25.0;
-BRepBuilderAPI_MakeCylinder aCylinder(aRadius, aHeight);
-TopoDS_Shape aShape = aCylinder.Shape();
-
-const Standard_Real aLinearDeflection = 0.01;
-const Standard_Real anAngularDeflection = 0.5;
+#include <IMeshData_Status.hxx>
+#include <IMeshTools_Parameters.hxx>
+#include <BRepMesh_IncrementalMesh.hxx>
+
+Standard_Boolean meshing_explicit_parameters()
+{
+ const Standard_Real aRadius = 10.0;
+ const Standard_Real aHeight = 25.0;
+ BRepPrimAPI_MakeCylinder aCylinder(aRadius, aHeight);
+ TopoDS_Shape aShape = aCylinder.Shape();
-BRepMesh_IncrementalMesh aMesh(aShape, aLinearDeflection, Standard_False, anAngularDeflection);
+ const Standard_Real aLinearDeflection = 0.01;
+ const Standard_Real anAngularDeflection = 0.5;
+ BRepMesh_IncrementalMesh aMesher (aShape, aLinearDeflection, Standard_False, anAngularDeflection, Standard_True);
+ const Standard_Integer aStatus = aMesher.GetStatusFlags();
+ return !aStatus;
+}
+
+Standard_Boolean meshing_imeshtools_parameters()
+{
+ const Standard_Real aRadius = 10.0;
+ const Standard_Real aHeight = 25.0;
+ BRepPrimAPI_MakeCylinder aCylinder(aRadius, aHeight);
+ TopoDS_Shape aShape = aCylinder.Shape();
+
+ IMeshTools_Parameters aMeshParams;
+ aMeshParams.Deflection = 0.01;
+ aMeshParams.Angle = 0.5;
+ aMeshParams.Relative = Standard_False;
+ aMeshParams.InParallel = Standard_True;
+ aMeshParams.MinSize = Precision::Confusion();
+ aMeshParams.InternalVerticesMode = Standard_True;
+ aMeshParams.ControlSurfaceDeflection = Standard_True;
+
+ BRepMesh_IncrementalMesh aMesher (aShape, aMeshParams);
+ const Standard_Integer aStatus = aMesher.GetStatusFlags();
+ return !aStatus;
+}
~~~~~
-The default meshing algorithm *BRepMesh_IncrementalMesh* has two major options to define triangulation – linear and angular deflections.
+The default meshing algorithm *BRepMesh_IncrementalMesh* has two major options to define triangulation -- linear and angular deflections.
At the first step all edges from a face are discretized according to the specified parameters.
At the second step, the faces are tessellated. Linear deflection limits the distance between a curve and its tessellation, whereas angular deflection limits the angle between subsequent segments in a polyline.
-@figure{/user_guides/modeling_algos/images/modeling_algos_image056.png, "Deflection parameters of BRepMesh_IncrementalMesh algorithm"}
+@figure{/user_guides/modeling_algos/images/modeling_algos_image056.png,"Deflection parameters of BRepMesh_IncrementalMesh algorithm",420}
Linear deflection limits the distance between triangles and the face interior.
-@figure{/user_guides/modeling_algos/images/modeling_algos_image057.png, "Linear deflection"}
+@figure{/user_guides/modeling_algos/images/modeling_algos_image057.png,"Linear deflection",420}
Note that if a given value of linear deflection is less than shape tolerance then the algorithm will skip this value and will take into account the shape tolerance.
Meshing covers a shape with a triangular mesh. Other than hidden line removal, you can use meshing to transfer the shape to another tool: a manufacturing tool, a shading algorithm, a finite element algorithm, or a collision algorithm.
-You can obtain information on the shape by first exploring it. To access triangulation of a face in the shape later, use *BRepTool::Triangulation*. To access a polygon, which is the approximation of an edge of the face, use *BRepTool::PolygonOnTriangulation*.
\ No newline at end of file
+You can obtain information on the shape by first exploring it. To access triangulation of a face in the shape later, use *BRepTool::Triangulation*. To access a polygon, which is the approximation of an edge of the face, use *BRepTool::PolygonOnTriangulation*.
+
+@subsection occt_modalg_11_3 BRepMesh Architecture
+@subsubsection occt_modalg_11_3_1 Goals
+
+The main goals of the chosen architecture are:
+ * Remove tight connections between data structures, auxiliary tools and algorithms in order to create an extensible solution, easy for maintenance and improvements;
+ * Separate the code among several functional units responsible for specific operation for the sake of simplification of debugging and readability;
+ * Introduce new data structures enabling the possibility to manipulate a discrete model of a particular entity (edge, wire, face) in order to perform computations locally instead of processing an entire model;
+ * Implement a new triangulation algorithm replacing existing functionality that contains too complicated solutions that need to be moved to the upper level. In addition, provide the possibility to change algorithm depending on surface type (initially to speed up meshing of planes).
+
+@subsubsection occt_modalg_11_3_2 General workflow
+@figure{/user_guides/modeling_algos/images/modeling_algos_mesh_001.svg,"General workflow of BRepMesh component",500}
+
+Generally, the workflow of the component can be divided on six parts:
+ * **Creation of model data structure**: source *TopoDS_Shape* passed to algorithm is analyzed and exploded on faces and edges. The reflection corresponding to each topological entity is created in the data model. Note that underlying algorithms use the data model as input and access it via a common interface which allows creating a custom data model with necessary dependencies between particular entities (see the paragraph "Data model interface");
+ * **Discretize edges 3D & 2D curves**: 3D curve as well as an associated set of 2D curves of each model edge is discretized in order to create a coherent skeleton used as a base in face meshing process. If an edge of the source shape already contains polygonal data which suits the specified parameters, it is extracted from the shape and stored in the model as is. Each edge is processed separately, adjacency is not taken into account;
+ * **Heal discrete model**: the source *TopoDS_Shape* can contain problems, such as open wires or self-intersections, introduced during design, exchange or modification of model. In addition, some problems like self-intersections can be introduced by roughly discretized edges. This stage is responsible for analysis of a discrete model in order to detect and repair problems or to refuse further processing of a model part in case if a problem cannot be solved;
+ * **Preprocess discrete model**: defines actions specific to the implemented approach to be performed before meshing of faces. By default, this operation iterates over model faces, checks the consistency of existing triangulations and cleans topological faces and adjacent edges from polygonal data in case of inconsistency or marks a face of the discrete model as not required for the computation;
+ * **Discretize faces**: represents the core part performing mesh generation for a particular face based on 2D discrete data. This operation caches polygonal data associated with face edges in the data model for further processing and stores the generated mesh to *TopoDS_Face*;
+ * **Postprocess discrete model**: defines actions specific for the implemented approach to be performed after meshing of faces. By default, this operation stores polygonal data obtained at the previous stage to *TopoDS_Edge* objects of the source model.
+
+@subsubsection occt_modalg_11_3_3 Common interfaces
+The component structure contains two units: <i>IMeshData</i> (see Data model interface) and <i>IMeshTools</i>, defining common interfaces for the data model and algorithmic tools correspondingly. Class *IMeshTools_Context* represents a connector between these units. The context class caches the data model as well as the tools corresponding to each of six stages of the workflow mentioned above and provides methods to call the corresponding tool safely (designed similarly to *IntTools_Context* in order to keep consistency with OCCT core tools). All stages, except for the first one use data model as input and perform a specific action on the entire structure. Thus, API class *IMeshTools_ModelAlgo* is defined in order to unify the interface of tools manipulating the data model. Each tool supposed to process the data model should inherit this interface enabling the possibility to cache it in context. In contrast to others, the model builder interface is defined by another class *IMeshTools_ModelBuilder* due to a different meaning of the stage. The entry point starting the entire workflow is represented by *IMeshTools_MeshBuilder*.
+
+The default implementation of *IMeshTools_Context* is given in *BRepMesh_Context* class initializing the context by instances of default algorithmic tools.
+
+The factory interface *IMeshTools_MeshAlgoFactory* gives the possibility to change the triangulation algorithm for a specific surface. The factory returns an instance of the triangulation algorithm via *IMeshTools_MeshAlgo* interface depending on the type of surface passed as parameter. It is supposed to be used at the face discretization stage.
+
+The default implementation of AlgoFactory is given in *BRepMesh_MeshAlgoFactory* returning algorithms of different complexity chosen according to the passed surface type. In its turn, it is used as the initializer of *BRepMesh_FaceDiscret* algorithm representing the starter of face discretization stage.
+
+@figure{/user_guides/modeling_algos/images/modeling_algos_mesh_002.svg,"Interface describing entry point to meshing workflow",500}
+
+Remaining interfaces describe auxiliary tools:
+ * *IMeshTools_CurveTessellator*: provides a common interface to the algorithms responsible for creation of discrete polygons on 3D and 2D curves as well as tools for extraction of existing polygons from *TopoDS_Edge* allowing to obtain discrete points and the corresponding parameters on curve regardless of the implementation details (see examples of usage of derived classes *BRepMesh_CurveTessellator*, *BRepMesh_EdgeTessellationExtractor* in *BRepMesh_EdgeDiscret*);
+ * *IMeshTools_ShapeExplorer*: the last two interfaces represent visitor design pattern and are intended to separate iteration over elements of topological shape (edges and faces) from the operations performed on a particular element;
+ * *IMeshTools_ShapeVisitor*: provides a common interface for operations on edges and faces of the target topological shape. It can be used in couple with *IMeshTools_ShapeExplorer*. The default implementation available in *BRepMesh_ShapeVisitor* performs initialization of the data model. The advantage of such approach is that the implementation of *IMeshTools_ShapeVisitor* can be changed according to the specific data model whereas the shape explorer implementation remains the same.
+
+@subsubsection occt_modalg_11_3_4 Create model data structure
+The data structures intended to keep discrete and temporary data required by underlying algorithms are created at the first stage of the meshing procedure. Generally, the model represents dependencies between entities of the source topological shape suitable for the target task.
+
+#### Data model interface
+Unit <i>IMeshData</i> provides common interfaces specifying the data model API used on different stages of the entire workflow. Dependencies and references of the designed interfaces are given in the figure below. A specific interface implementation depends on the target application which allows the developer to implement different models and use custom low-level data structures, e.g. different collections, either <i>NCollection</i> or STL. *IMeshData_Shape* is used as the base class for all data structures and tools keeping the topological shape in order to avoid possible copy-paste.
+
+The default implementation of interfaces is given in <i>BRepMeshData</i> unit. The main aim of the default data model is to provide features performing discretization of edges in a parallel mode. Thus, curve, pcurve and other classes are based on STL containers and smart-pointers as far as <i>NCollection</i> does not provide thread-safety for some cases (e.g. *NCollection_Sequence*). In addition, it closely reflects topology of the source shape, i.e. the number of edges in the data model is equal to the number of edges in the source model; each edge contains a set of pcurves associated with its adjacent faces which allows creation of discrete polygons for all pcurves or the 3D curve of a particular edge in a separate thread.
+
+**Advantages**:
+In case of necessity, the data model (probably with algorithms for its processing) can be easily substituted by another implementation supporting another kind of dependencies between elements.
+
+An additional example of a different data model is the case when it is not required to create a mesh with discrete polygons synchronized between adjacent faces, i.e. in case of necessity to speed up creation of a rough per-face tessellation used for visualization or quick computation only (the approach used in *XDEDRAW_Props*).
+
+@figure{/user_guides/modeling_algos/images/modeling_algos_mesh_003.svg,"Common API of data model",500}
+
+#### Collecting data model
+At this stage the data model is filled by entities according to the topological structure of the source shape. A default implementation of the data model is given in <i>BRepMeshData</i> unit and represents the model as two sets: a set of edges and a set of faces. Each face consists of one or several wires, the first of which always represents the outer wire, while others are internal. In its turn, each wire depicts the ordered sequence of oriented edges. Each edge is characterized by a single 3D curve and zero (in case of free edge) or more 2D curves associated with faces adjacent to this edge. Both 3D and 2D curves represent a set of pairs point-parameter defined in 3D and 2D space of the reference face correspondingly. An additional difference between a curve and a pcurve is that the latter has a reference to the face it is defined for.
+
+Model filler algorithm is represented by *BRepMesh_ShapeVisitor* class creating the model as a reflection to topological shape with help of *BRepMesh_ShapeExplorer* performing iteration over edges and faces of the target shape. Note that the algorithm operates on a common interface of the data model and creates a structure without any knowledge about the implementation details and underlying data structures. The entry point to collecting functionality is *BRepMesh_ModelBuilder* class.
+
+@subsubsection occt_modalg_11_3_5 Discretize edges 3D & 2D curves
+At this stage only the edges of the data model are considered. Each edge is processed separately (with the possibility to run processing in multiple threads). The edge is checked for existing polygonal data. In case if at least one representation exists and suits the meshing parameters, it is recuperated and used as reference data for tessellation of the whole set of pcurves as well as 3D curve assigned to the edge (see *BRepMesh_EdgeTessellationExtractor*). Otherwise, a new tessellation algorithm is created and used to generate the initial polygon (see *BRepMesh_CurveTessellator*) and the edge is marked as outdated. In addition, the model edge is updated by deflection as well as recomputed same range, same parameter and degeneracy parameters. See *BRepMesh_EdgeDiscret* for implementation details.
+
+<i>IMeshData</i> unit defines interface *IMeshData_ParametersListArrayAdaptor*, which is intended to adapt arbitrary data structures to the *NCollection_Array1* container API. This solution is made to use both *NCollection_Array1* and *IMeshData_Curve* as the source for *BRepMesh_EdgeParameterProvider* tool intended to generate a consistent parametrization taking into account the same parameter property.
+
+@subsubsection occt_modalg_11_3_6 Heal discrete model
+In general, this stage represents a set of operations performed on the entire discrete model in order to resolve inconsistencies due to the problems caused by design, translation or rough discretization. A different sequence of operations can be performed depending on the target triangulation algorithm, e.g. there are different approaches to process self-intersections – either to amplify edges discretization by decreasing the target precision or to split links at the intersection points. At this stage the whole set of edges is considered in aggregate and their adjacency is taken into account. A default implementation of the model healer is given in *BRepMesh_ModelHealer* which performs the following actions:
+ * Iterates over model faces and checks their wires for consistency, i.e. whether the wires are closed and do not contain self-intersections. The data structures are designed free of collisions, thus it is possible to run processing in a parallel mode;
+ * Forcibly connects the ends of adjacent edges in the parametric space, closing gaps between possible disconnected parts. The aim of this operation is to create a correct discrete model defined relatively to the parametric space of the target face taking into account connectivity and tolerances of 3D space only. This means that no specific computations are made to determine U and V tolerance;
+ * Registers intersections on edges forming the face shape. Two solutions are possible in order to resolve self-intersection:
+ * Decrease deflection of a particular edge and update its discrete model. After that the workflow "intersection check – amplification" is repeated up to 5 times. As the result, target edges contain a finer tessellation and meshing continues or the face is marked by *IMeshData_SelfIntersectingWire* status and refused from further processing;
+ * Split target edges by intersection point and synchronize the updated polygon with curve and remaining pcurves associated to each edge. This operation presents a more robust solution comparing to the amplification procedure with a guaranteed result, but it is more difficult for implementation from the point of view of synchronization functionality.
+
+@subsubsection occt_modalg_11_3_7 Preprocess discrete model
+This stage implements actions to be performed before meshing of faces. Depending on target goals it can be changed or omitted. By default, *BRepMesh_ModelPreProcessor* implements the functionality checking topological faces for consistency of existing triangulation, i.e.: consistency with the target deflection parameter; indices of nodes referenced by triangles do not exceed the number of nodes stored in a triangulation. If the face fails some checks, it is cleaned from triangulation and its adjacent edges are cleaned from existing polygons. This does not affect a discrete model and does not require any recomputation as the model keeps tessellations for the whole set of edges despite consistency of their polygons.
+
+@subsubsection occt_modalg_11_3_8 Discretize faces
+Discretization of faces is the general part of meshing algorithm. At this stage edges tessellation data obtained and processed on previous steps is used to form contours of target faces and passed as input to the triangulation algorithm. Default implementation is provided by *BRepMesh_FaceDiscret* class which represents a starter for triangulation algorithm. It iterates over faces available in the data model, creates an instance of the triangulation algorithm according to the type of surface associated with each face via *IMeshTools_MeshAlgoFactory* and executes it. Each face is processed separately, thus it is possible to process faces in a parallel mode. The class diagram of face discretization is given in the figure below.
+
+@figure{/user_guides/modeling_algos/images/modeling_algos_mesh_004.svg,"Class diagram of face discrete stage",300}
+
+In general, face meshing algorithms have the following structure:
+ * *BRepMesh_BaseMeshAlgo* implements *IMeshTools_MeshAlgo* interface and the base functionality for inherited algorithms. The main goal of this class is to initialize an instance of *BRepMesh_DataStructureOfDelaun* as well as auxiliary data structures suitable for nested algorithms using face model data passed as input parameter. Despite implementation of triangulation algorithm this structure is currently supposed as common for OCCT. However, the user is free to implement a custom algorithm and supporting data structure accessible via *IMeshTools_MeshAlgo* interface, e.g. to connect a 3-rd party meshing tool that does not support *TopoDS_Shape* out of box. For this, such structure provides the possibility to distribute connectors to various algorithms in the form of plugins;
+ * *BRepMesh_DelaunayBaseMeshAlgo* and *BRepMesh_SweepLineMeshAlgo* classes implement core meshing functionality operating directly on an instance of *BRepMesh_DataStructureOfDelaun*. The algorithms represent mesh generation tools adding new points from the data structure to the final mesh;
+ * *BRepMesh_NodeInsertionMeshAlgo* class represents a wrapper intended to extend the algorithm inherited from *BRepMesh_BaseMeshAlgo* to enable the functionality generating surface nodes and inserting them into the structure. On this level, an instance of the classification tool is created and can be used to accept-reject internal nodes. In addition, computations necessary for scaling UV coordinates of points relatively to the range specified for the corresponding direction are performed. As far as both triangulation algorithms work on static data provided by the structure, new nodes are added at the initialization stage. Surface nodes are generated by an auxiliary tool called range splitter and passed as template parameter (see Range splitter);
+ * Classes *BRepMesh_DelaunayNodeInsertionMeshAlgo* and *BRepMesh_SweepLineNodeInsertionMeshAlgo* implement algorithm-specific functionality related to addition of internal nodes supplementing functionality provided by *BRepMesh_NodeInsertionMeshAlgo*;
+ * *BRepMesh_DelaunayDeflectionControlMeshAlgo* extends functionality of *BRepMesh_DelaunayNodeInsertionMeshAlgo* by additional procedure controlling deflection of generated triangles.
+
+#### Range splitter
+Range splitter tools provide functionality to generate internal surface nodes defined within the range computed using discrete model data. The base functionality is provided by *BRepMesh_DefaultRangeSplitter* which can be used without modifications in case of planar surface. The default splitter does not generate any internal node.
+
+*BRepMesh_ConeRangeSplitter*, *BRepMesh_CylinderRangeSplitter* and *BRepMesh_SphereRangeSplitter* are specializations of the default splitter intended for quick generation of internal nodes for the corresponding type of analytical surface.
+
+*BRepMesh_UVParamRangeSplitter* implements base functionality taking discretization points of face border into account for node generation. Its successors BRepMesh_TorusRangeSplitter and *BRepMesh_NURBSRangeSplitter* extend the base functionality for toroidal and NURBS surfaces correspondingly.
+
+@subsubsection occt_modalg_11_3_9 Postprocess discrete model
+This stage implements actions to be performed after meshing of faces. Depending on target goals it can be changed or omitted. By default, *BRepMesh_ModelPostProcessor* commits polygonal data stored in the data model to *TopoDS_Edge*.
+
+
+@section occt_modalg_defeaturing 3D Model Defeaturing
+
+The Open CASCADE Technology Defeaturing algorithm is intended for removal of the unwanted parts or features from the model. These parts can be holes, protrusions, gaps, chamfers, fillets, etc.
+
+Feature detection is not performed, and all features to be removed should be defined by the user. The input shape is not modified during Defeaturing, the new shape is built in the result.
+
+On the API level the Defeaturing algorithm is implemented in the *BRepAlgoAPI_Defeaturing* class. At input the algorithm accepts the shape to remove the features from and the features (one or many) to be removed from the shape.
+Currently, the input shape should be either SOLID, or COMPSOLID, or COMPOUND of SOLIDs.
+The features to be removed are defined by the sets of faces forming them. It does not matter how the feature faces are given: as separate faces or their collections. The faces should belong to the initial shape, else they are ignored.
+
+The actual features removal is performed by the low-level *BOPAlgo_RemoveFeatures* algorithm. On the API level, all inputs are passed into the tool and the method *BOPAlgo_RemoveFeatures::Perform()* is called.
+
+Before removing features, all faces to be removed from the shape are sorted into connected blocks - each block represents a single feature to be removed.
+The features are removed from the shape one by one, which allows removing all possible features even if there are some problems with their removal (e.g. due to incorrect input data).
+
+The removed feature is filled by the extension of the faces adjacent to it. In general, the algorithm removing a single feature from the shape goes as follows:
+* Find the faces adjacent to the feature;
+* Extend the adjacent faces to cover the feature;
+* Trim the extended faces by the bounds of the original face (except for the bounds common with the feature), so that they cover the feature only;
+* Rebuild the solids with reconstructed adjacent faces avoiding the feature faces.
+
+If the single feature removal was successful, the result shape is overwritten with the new shape, otherwise the results are not kept, and the warning is given.
+Either way the process continues with the next feature.
+
+The Defeaturing algorithm has the following options:
+* History support;
+
+and the options available from base class (*BOPAlgo_Options*):
+* Error/Warning reporting system;
+* Parallel processing mode.
+
+Note that the other options of the base class are not supported here and will have no effect.
+
+<b>History support</b> allows tracking modification of the input shape in terms of Modified, IsDeleted and Generated. By default, the history is collected, but it is possible to disable it using the method *SetToFillHistory(false)*.
+On the low-level the history information is collected by the history tool *BRepTools_History*, which can be accessed through the method *BOPAlgo_RemoveFeatures::History()*.
+
+<b>Error/Warning reporting system</b> allows obtaining the extended overview of the Errors/Warnings occurred during the operation. As soon as any error appears, the algorithm stops working. The warnings allow continuing the job and informing the user that something went wrong. The algorithm returns the following errors/warnings:
+* *BOPAlgo_AlertUnsupportedType* - the alert will be given as an error if the input shape does not contain any solids, and as a warning if the input shape contains not only solids, but also other shapes;
+* *BOPAlgo_AlertNoFacesToRemove* - the error alert is given in case there are no faces to remove from the shape (nothing to do);
+* *BOPAlgo_AlertUnableToRemoveTheFeature* - the warning alert is given to inform the user the removal of the feature is not possible. The algorithm will still try to remove the other features;
+* *BOPAlgo_AlertRemoveFeaturesFailed* - the error alert is given in case if the operation was aborted by the unknown reason.
+
+For more information on the error/warning reporting system, see the chapter @ref occt_algorithms_ers "Errors and warnings reporting system" of Boolean operations user guide.
+
+<b>Parallel processing mode</b> - allows running the algorithm in parallel mode obtaining the result faster.
+
+The algorithm has certain limitations:
+* Intersection of the surfaces of the connected faces adjacent to the feature should not be empty. It means, that such faces should not be tangent to each other.
+If the intersection of the adjacent faces will be empty, the algorithm will be unable to trim the faces correctly and, most likely, the feature will not be removed.
+* The algorithm does not process the INTERNAL parts of the solids, they are simply removed during reconstruction.
+
+Note, that for successful removal of the feature, the extended faces adjacent to the feature should cover the feature completely, otherwise the solids will not be rebuild.
+Take a look at the simple shape on the image below:
+@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im001.png,"",220}
+
+Removal of all three faces of the gap is not going to work, because there will be no face to fill the transverse part of the step.
+Although, removal of only two faces, keeping one of the transverse faces, will fill the gap with the kept face:
+<table align="center">
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im002.png,"Keeping the right transverse face",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im003.png,"Keeping the left transverse face",220}</td>
+</tr>
+</table>
+
+@subsection occt_modalg_defeaturing_usage Usage
+
+Here is the example of usage of the *BRepAlgoAPI_Defeaturing* algorithm on the C++ level:
+~~~~
+TopoDS_Shape aSolid = ...; // Input shape to remove the features from
+TopTools_ListOfShape aFeatures = ...; // Features to remove from the shape
+Standard_Boolean bRunParallel = ...; // Parallel processing mode
+Standard_Boolean isHistoryNeeded = ...; // History support
+
+BRepAlgoAPI_Defeaturing aDF; // Defeaturing algorithm
+aDF.SetShape(aSolid); // Set the shape
+aDF.AddFacesToRemove(aFaces); // Add faces to remove
+aDF.SetRunParallel(bRunParallel); // Define the processing mode (parallel or single)
+aDF.SetToFillHistory(isHistoryNeeded); // Define whether to track the shapes modifications
+aDF.Build(); // Perform the operation
+if (!aDF.IsDone()) // Check for the errors
+{
+ // error treatment
+ Standard_SStream aSStream;
+ aDF.DumpErrors(aSStream);
+ return;
+}
+if (aDF.HasWarnings()) // Check for the warnings
+{
+ // warnings treatment
+ Standard_SStream aSStream;
+ aDF.DumpWarnings(aSStream);
+}
+const TopoDS_Shape& aResult = aDF.Shape(); // Result shape
+~~~~
+
+Use the API history methods to track the history of a shape:
+~~~~
+// Obtain modification of the shape
+const TopTools_ListOfShape& BRepAlgoAPI_Defeaturing::Modified(const TopoDS_Shape& theS);
+
+// Obtain shapes generated from the shape
+const TopTools_ListOfShape& BRepAlgoAPI_Defeaturing::Generated(const TopoDS_Shape& theS);
+
+// Check if the shape is removed or not
+Standard_Boolean BRepAlgoAPI_Defeaturing::IsDeleted(const TopoDS_Shape& theS);
+~~~~
+
+The command <b>removefeatures</b> allows using the Defeaturing algorithm on the Draw level.
+
+The @ref occt_draw_hist "standard history commands" can be used to track the history of shape modification during Defeaturing.
+
+For more details on commands above, refer to the @ref occt_draw_defeaturing "Defeaturing commands" of the Draw test harness user guide.
+
+@subsection occt_modalg_defeaturing_examples Examples
+
+Here are the examples of defeaturing of the ANC101 model:
+
+@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im004.png,"ANC101 model",220}</td>
+
+<table align="center">
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im005.png,"Removing the cylindrical protrusion",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im006.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im007.png,"Removing the cylindrical holes",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im008.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im009.png,"Removing the cylindrical holes",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im010.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im011.png,"Removing the small gaps in the front",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im012.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im013.png,"Removing the gaps in the front completely",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im014.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im015.png,"Removing the cylindrical protrusion",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im016.png,"Result",220}</td></td>
+</tr>
+</table>
+
+Here are the few examples of defeaturing of the model containing boxes with blends:
+
+@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im017.png,"Box blend model",220}</td>
+
+<table align="center">
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im018.png,"Removing the blend",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im019.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im020.png,"Removing the blend",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im021.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im022.png,"Removing the blend",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im023.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im024.png,"Removing the blend",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im025.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im026.png,"Removing the blend",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im027.png,"Result",220}</td></td>
+</tr>
+<tr>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im028.png,"Removing the blend",220}</td>
+ <td>@figure{/user_guides/modeling_algos/images/modeling_algos_rf_im029.png,"Result",220}</td></td>
+</tr>
+</table>
projects / occt.git / blobdiff