Defined in File Ifc4.h
IfcCurveBoundedSurface: public Ifc4::IfcBoundedSurface¶
Definition from ISO/CD 10303-42:1992 The curve bounded surface is a parametric surface with curved boundaries defined by one or more boundary curves. One of the boundary curves may be the outer boundary; any number of inner boundaries is permissible. The region of the curve bounded surface in the basis surface is defined to be the portion of the basis surface in the direction of N x T from any point on the boundary, where N is the surface normal and T the boundary curve tangent vector at this point. The region so defined shall be arcwise connected.
The IfcCurveBoundedSurface is a parametric surface with boundaries defined by p-curves, that is, a curve which lies on the basis of a surface and is defined in the parameter space of that surface. The p-curve is a special type of a composite curve segment and shall only be used to bound a surface.
The outer boundary shall be either defined by:
an IfcOuterBoundaryCurve, a closed composite curve on surface for the definition of an outer boundary, then the attribute ImplicitOuter has to be set to FALSE, or by the implicit boundary of the bounded surface, e.g. the u1, u2, v1, v2 of IfcRectangularTrimmedSurface< then the attribute ImplicitOuter has to be set to TRUE. Note that some surfaces, like IfcCylindricalSurface does not have identifiable implicit boundaries.
NOTE Corresponding STEP entity: curve_bounded_surface. Please refer to ISO/IS 10303-42:1994, p.87 for the final definition of the formal standard.
HISTORY New entity in IFC2x4.
Each curve in the set of Boundaries shall be closed. No two curves in the set of Boundaries shall intersect. At most one of the boundary curves may enclose any other boundary curve. If an IfcOuterBoundaryCurve is designated, only that curve may enclose any other boundary curve.
The outer boundary of the surface.