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BSpline BRep Objects

BSpline BRep 3D Object is the section type created during import of solids via STEP or IGES formats. It is the most flexible parametric representation of objects with surfaces.

BSpline BRep objects can also be created programmatically using IStdShape Interface obtained via IKO_Model (details) or using Model Explorer. BSpline BRep objects are also created during various operations like through (generalised extrusion) operation.

IKO_BRep_Builder interface allows building BSpline BRep objects from the ground up by defining geometry of its vertices, edges and faces. See ShapeBuilder class implementation in Shape Explorer sample for an example.

Geometry of a BSpline BRep 3D Object (section) is represented by a shape. Shape has only purely geometric attributes. Most of shapes have sub shapes.

A shape representing BSpline BRep object normally is a shape organised hierarchically: The top shape is one or several shells. Shells are sets of joned together faces which often constitute a closed surface.

A shell consists of faces (Details). A face is a smooth (not necessarily flat) piece of surface with several edges. For example a rectangle in 3D is normally represented by a flat face with four edges. Faces are sub shapes of shells.

An edge can be either straight or curved, but always smooth curve with two ends. Ends of an edge may coincide, in which case the curve is closed.

A linked sequence of edges is called a wire. Wires are sub shapes of faces. Edges are sub shapes of faces and wires.

A vertex, which represents a point with some other non-geometrical additional information, is the lowest-level sub shape. Ends of edges are vertices. Corners of a patch are also vertices.

Solid is a shape represented by a single closed shell

Structure of a shape can be discovered at runtime using IKO_TopExp_Explorer

See also: Shape Explorer Sample