8.9.6.23 IfcSecondProjAxis（第二投影轴）

8.9.6.23.1 语义定义（Semantic definition）

8.9.6.23.2 形式化表示（Formal representation）

FUNCTION IfcSecondProjAxis
  (ZAxis, XAxis, Arg: IfcDirection) 
    : IfcDirection;
LOCAL
  YAxis : IfcVector;
  V     : IfcDirection;
  Temp  : IfcVector;
END_LOCAL;

  IF NOT EXISTS(Arg) THEN
    V := IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.0,1.0,0.0]);
  ELSE
    V := Arg;
  END_IF;
  Temp  := IfcScalarTimesVector(IfcDotProduct(V, ZAxis), ZAxis);
  YAxis := IfcVectorDifference(V, Temp);
  Temp  := IfcScalarTimesVector(IfcDotProduct(V, XAxis), XAxis);
  YAxis := IfcVectorDifference(YAxis, Temp);
  YAxis := IfcNormalise(YAxis);
  RETURN(YAxis.Orientation);

END_FUNCTION;

8.9.6.23.3 参考文献

IfcBaseAxis