8.9.2.4 IfcBSplineSurfaceForm

8.9.2.4.1 Semantic definition

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

8.9.2.4.2 Type values

Type	Description
`CONICAL_SURF`	A bounded portion of the surface of a right circular cone.
`CYLINDRICAL_SURF`	A bounded portion of a cylindrical surface.
`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.
`PLANE_SURF`	A bounded portion of a plane represented by a B-spline surface of degree 1 in each parameter.
`QUADRIC_SURF`	A bounded portion of one of the class of surfaces of degree 2 in the variables x, y and z.
`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.
`SPHERICAL_SURF`	A bounded portion of a sphere, or a complete sphere, represented by a B-spline surface.
`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.
`SURF_OF_REVOLUTION`	A bounded portion of a surface of revolution.
`TOROIDAL_SURF`	A torus, or portion of a torus, represented by a B-spline surface.
`UNSPECIFIED`	A surface for which no particular form is specified.

Table 8.9.2.4.A

8.9.2.4.3 Formal representation

TYPE IfcBSplineSurfaceForm = ENUMERATION OF
	(CONICAL_SURF
	,CYLINDRICAL_SURF
	,GENERALISED_CONE
	,PLANE_SURF
	,QUADRIC_SURF
	,RULED_SURF
	,SPHERICAL_SURF
	,SURF_OF_LINEAR_EXTRUSION
	,SURF_OF_REVOLUTION
	,TOROIDAL_SURF
	,UNSPECIFIED);
END_TYPE;

8.9.2.4.4 References

IfcBSplineSurface