IfcConvertDirectionInto2D
该函数使用二维或三维方向的x/y比率作为输入，返回二维方向。
注意：此函数当前仅用于确定IfcGeometricRepresentationSubContext中的TrueNorth方向。
IFC2x4中的新函数。
EXPRESS Specification
FUNCTION IfcConvertDirectionInto2D
(Direction : IfcDirection)
: IfcDirection;
LOCAL
Direction2D : IfcDirection := IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.,1.]);
END_LOCAL;
Direction2D.DirectionRatios[1] := Direction.DirectionRatios[1];
Direction2D.DirectionRatios[2] := Direction.DirectionRatios[2];
RETURN (Direction2D);
END_FUNCTION;
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