8.9.3.48 IfcPointByDistanceExpression
8.9.3.48.1 Semantic definition
An IfcPointByDistanceExpression describes a point relative to a basis curve according to distance along the basis curve. The offsets default to the initial context of the curve relative to it's tangent either specified in IfcProduct.Placement or in the case of a segmented curve to the IfcCurveSegment StartPlacement where the values correspond to the following:
- lateral to the basis curve
- offset vertical to the basis curve
- optional additional offset parallel to the basis curve that may be used to address locations otherwise unreachable where the basis curve is tangentially discontinuous.
8.9.3.48.2 Entity inheritance
-
- IfcPoint
- IfcAnnotationFillArea
- IfcBooleanResult
- IfcBoundingBox
- IfcCartesianPointList
- IfcCartesianTransformationOperator
- IfcCsgPrimitive3D
- IfcCurve
- IfcDirection
- IfcFaceBasedSurfaceModel
- IfcFillAreaStyleHatching
- IfcFillAreaStyleTiles
- IfcGeometricSet
- IfcHalfSpaceSolid
- IfcLightSource
- IfcPlacement
- IfcPlanarExtent
- IfcSectionedSpine
- IfcSegment
- IfcShellBasedSurfaceModel
- IfcSolidModel
- IfcSurface
- IfcTessellatedItem
- IfcTextLiteral
- IfcVector
8.9.3.48.3 Attributes
# | Attribute | Type | Description |
---|---|---|---|
IfcRepresentationItem (2) | |||
IfcPoint (1) | |||
Click to show 3 hidden inherited attributes Click to hide 3 inherited attributes | |||
IfcPointByDistanceExpression (5) | |||
1 | DistanceAlong | IfcCurveMeasureSelect |
The distance along the basis curve measured as either a IfcLengthMeasure or IfcParameterValue. |
2 | OffsetLateral | OPTIONAL IfcLengthMeasure |
Default offset horizontally is measured perpendicular to the basis curve, where positive values indicate to the left of the basis curve as facing in the positive parametrization direction of the basis curve, and negative values indicate to the right. If DistanceAlong coincides with a point of tangential discontinuity (within precision limits), then the tangent of the previous segment governs. |
3 | OffsetVertical | OPTIONAL IfcLengthMeasure |
Default offset vertical to the basis curve where positive values indicate perpendicular to the tangent at DistanceAlong in the plane of the tangent perpendicular to the global XY plane. |
4 | OffsetLongitudinal | OPTIONAL IfcLengthMeasure |
Offset parallel to the basis curve after applying DistanceAlong, OffsetLateral, and OffsetVertical to reach locations for the case of a tangentially discontinuous basis curve. |
5 | BasisCurve | IfcCurve |
No description available. |
8.9.3.48.4 Examples
8.9.3.48.5 Formal representation
ENTITY IfcPointByDistanceExpression SUBTYPE OF (IfcPoint); DistanceAlong : IfcCurveMeasureSelect; OffsetLateral : OPTIONAL IfcLengthMeasure; OffsetVertical : OPTIONAL IfcLengthMeasure; OffsetLongitudinal : OPTIONAL IfcLengthMeasure; BasisCurve : IfcCurve; END_ENTITY;