IfcBSplineSurfaceForm

Item	SPF	XML	Change	Description
IFC2x3 to IFC4
IfcBSplineSurfaceForm			ADDED

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

Constant	Description
PLANE_SURF	A bounded portion of a plane represented by a B-spline surface of degree 1 in each parameter.
CYLINDRICAL_SURF	A bounded portion of a cylindrical surface.
CONICAL_SURF	A bounded portion of the surface of a right circular cone.
SPHERICAL_SURF	A bounded portion of a sphere, or a complete sphere, represented by a B-spline surface.
TOROIDAL_SURF	A torus, or portion of a torus, represented by a B-spline surface.
SURF_OF_REVOLUTION	A bounded portion of a surface of revolution.
RULED_SURF	A surface constructed from two parametric curves by joining with straight lines corresponding points with the same parameter value on each of the curves.
GENERALISED_CONE	A 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_SURF	A bounded portion of one of the class of surfaces of degree 2 in the variables x, y and z.
SURF_OF_LINEAR_EXTRUSION	A bounded portion of a surface of linear extrusion represented by a B-spline surface of degree 1 in one of the parameters.
UNSPECIFIED	A 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;


 EXPRESS-G diagram

	Bézier-Spline-Flächen (verschiedene Formen)
	BSpline Surface Form
	Forme de surface Bspline