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agreement on usage and override sequence of curve colors
based on
extended coordination view
24. Nov 2006
ISG meeting in Dijon
summary agreement on usage of curve colors and override sequence




Since IFC2x3 the use of the property set Pset_Draughting (see #CV-2x3-109) is deprecated and it shall no longer be used. The assignment of color to the shape representation (here to the curve style associated to curves being part of the shape representation) is handled by:

  • IfcCurveStyle.CurveColour


It can be assigned to the element having a shape representation via:

  • explicitly (directly attached to geometry) - subtype of IfcGeometricRepresentationItem inverse relationship StyledByItem pointing to IfcStyledItem.Styles (IfcPresentationStyleAssignment) being an IfcCurveStyle
  • explicitly (indirectly attached to presentation layer) - subtype of IfcGeometricRepresentationItem inverse relationship LayerAssignments, or IfcShapeRepresentation inverse relationship LayerAssignments pointing to the subtype IfcPresentationLayerWithStyle (see also #CV-2x3-129). The IfcPresentationLayerWithStyle.LayerStyles points to the IfcCurveStyle.
  • implicitly (attached to the material information used for parametric definition of element shape) - IfcMaterial.HasRepresentation (IfcMaterialDefinitionRepresentation) with the attribute Representations refering to IfcStyledRepresentation.Items being IfcStyledItem's. Then IfcStyledItem.Styles (IfcPresentationStyleAssignment) being an IfcCurveStyle


All three ways of assigning a line color are supported for import in the IFC2x3 coordination view. The sequence for overriding is:

  • check for the layer color (if available)
  • override it (if available) by the material color
  • override if (if available) by the explicit geometric item color.