IFC 4.3.0.1 (IFC4X3) development

8.9.2.12 IfcTransitionCode

8.9.2.12.1 Semantic definition

The IfcTransitionCode indicated the continuity between consecutive segments of a curve or surface.

Figure 8.9.2.12.A illustrates transition types

transition code
Figure 8.9.2.12.A — Transition code

8.9.2.12.2 Type values

Type Description
CONTINUOUS

The segments join but no condition on their tangents is implied.

CONTSAMEGRADIENT

The segments join and their tangent vectors or tangent planes are parallel and have the same direction at the joint: equality of derivatives is not required.

CONTSAMEGRADIENTSAMECURVATURE

For a curve, the segments join, their tangent vectors are parallel and in the same direction and their curvatures are equal at the joint: equality of derivatives is not required. For a surface this implies that the principle curvatures are the same and the principle directions are coincident along the common boundary.

DISCONTINUOUS

The segments do not join. This is permitted only at the boundary of the curve or surface to indicate that it is not closed.

Table 8.9.2.12.B

8.9.2.12.3 Formal representation

TYPE IfcTransitionCode = ENUMERATION OF
	(CONTINUOUS
	,CONTSAMEGRADIENT
	,CONTSAMEGRADIENTSAMECURVATURE
	,DISCONTINUOUS);
END_TYPE;

8.9.2.12.4 References

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