Defined in File Ifc4x1.h
IfcOffsetCurve2D: public Ifc4x1::IfcOffsetCurve¶
Definition from ISO/CD 10303-42:1992: An offset curve 2d (IfcOffsetCurve2d) is a curve at a constant distance from a basis curve in two-dimensional space. This entity defines a simple plane-offset curve by offsetting by distance along the normal to basis curve in the plane of basis curve. The underlying curve shall have a well-defined tangent direction at every point. In the case of a composite curve, the transition code between each segment shall be cont same gradient or cont same gradient same curvature.
NOTE: The offset curve 2d may differ in nature from the basis curve; the offset of a non self- intersecting curve can be self-intersecting. Care should be taken to ensure that the offset to a continuous curve does not become discontinuous.
The offset curve 2d takes its parameterization from the basis curve. The offset curve 2d is parameterized as
where T is the unit tangent vector to the basis curve C(u) at parameter value u, and d is distance. The underlying curve shall be two-dimensional.
NOTE Corresponding ISO 10303 entity: offset_curve_2d, Please refer to ISO/IS 10303-42:1994, p.65 for the final definition of the formal standard.
HISTORY New entity in IFC Release 2.x
The distance of the offset curve from the basis curve. distance may be positive, negative or zero. A positive value of distance defines an offset in the direction which is normal to the curve in the sense of an anti-clockwise rotation through 90 degrees from the tangent vector T at the given point. (This is in the direction of orthogonal complement(T).)
An indication of whether the offset curve self-intersects; this is for information only.