IfcTransitionCode indicates the continuity between consecutive segments of a curve or surface.
Figure 8.9.2.12.A illustrates transition types
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;
