IfcBSplineSurfaceForm

Natural language names
Bézier-Spline-Flächen (verschiedene Formen)
BSpline Surface Form
Forme de surface Bspline
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4
    IfcBSplineSurfaceFormADDED
Semantic definitions at the type
Type definition

The IfcBSplineSurfaceForm represents a part of a surface of some specific form.

NOTE  Definition according to ISO/CD 10303-42:1992
This type is used to indicate that the B-spline surface represents a part of a surface of some specific form.
NOTE  Type adapted from b_spline_surface_form defined in ISO 10303-42.
HISTORY  New type in IFC4.
Enumeration definition
ConstantDescription
PLANE_SURFA bounded portion of a plane represented by a B-spline surface of degree 1 in each parameter.
CYLINDRICAL_SURFA bounded portion of a cylindrical surface.
CONICAL_SURFA bounded portion of the surface of a right circular cone.
SPHERICAL_SURFA bounded portion of a sphere, or a complete sphere, represented by a B-spline surface.
TOROIDAL_SURFA torus, or portion of a torus, represented by a B-spline surface.
SURF_OF_REVOLUTIONA bounded portion of a surface of revolution.
RULED_SURFA surface constructed from two parametric curves by joining with straight lines corresponding points with the same parameter value on each of the curves.
GENERALISED_CONEA special case of a ruled surface in which the second curve degenerates to a single point; when represented by a B-spline surface all the control points along one edge will be coincident.
QUADRIC_SURFA bounded portion of one of the class of surfaces of degree 2 in the variables x, y and z.
SURF_OF_LINEAR_EXTRUSIONA bounded portion of a surface of linear extrusion represented by a B-spline surface of degree 1 in one of the parameters.
UNSPECIFIEDA surface for which no particular form is specified.
Formal representations
XML Specification
 <xs:simpleType name="IfcBSplineSurfaceForm">
  <xs:restriction base="xs:string">
   <xs:enumeration value="plane_surf"/>
   <xs:enumeration value="cylindrical_surf"/>
   <xs:enumeration value="conical_surf"/>
   <xs:enumeration value="spherical_surf"/>
   <xs:enumeration value="toroidal_surf"/>
   <xs:enumeration value="surf_of_revolution"/>
   <xs:enumeration value="ruled_surf"/>
   <xs:enumeration value="generalised_cone"/>
   <xs:enumeration value="quadric_surf"/>
   <xs:enumeration value="surf_of_linear_extrusion"/>
   <xs:enumeration value="unspecified"/>
  </xs:restriction>
 </xs:simpleType>
EXPRESS Specification
TYPE IfcBSplineSurfaceForm = ENUMERATION OF (
 PLANE_SURF,
 CYLINDRICAL_SURF,
 CONICAL_SURF,
 SPHERICAL_SURF,
 TOROIDAL_SURF,
 SURF_OF_REVOLUTION,
 RULED_SURF,
 GENERALISED_CONE,
 QUADRIC_SURF,
 SURF_OF_LINEAR_EXTRUSION,
 UNSPECIFIED);
END_TYPE;

Link to EXPRESS-G diagram EXPRESS-G diagram

References  References: IfcBSplineSurface

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