8.9.6.6 IfcConstraintsParamBSpline

8.9.6.6.1 Semantic definition

8.9.6.6.2 Formal representation

FUNCTION IfcConstraintsParamBSpline
( Degree, UpKnots, UpCp : INTEGER;
  KnotMult : LIST OF INTEGER;
  Knots : LIST OF IfcParameterValue ) 
: BOOLEAN;
 
 
  LOCAL
    Result : BOOLEAN := TRUE;
    K, Sum : INTEGER;
  END_LOCAL;
 
  (* Find sum of knot multiplicities. *)
  Sum := KnotMult[1];
  REPEAT i := 2 TO UpKnots;
    Sum := Sum + KnotMult[i];
  END_REPEAT;
 
  (* Check limits holding for all B-spline parametrisations *)
  IF (Degree < 1) OR (UpKnots < 2) OR (UpCp < Degree) OR
    (Sum <> (Degree + UpCp + 2)) THEN
    Result := FALSE;
    RETURN(Result);
  END_IF;
 
  K := KnotMult[1];
  IF (K < 1) OR (K > Degree + 1) THEN
    Result := FALSE;
    RETURN(Result);
  END_IF;
 
  REPEAT i := 2 TO UpKnots;
    IF (KnotMult[i] < 1) OR (Knots[i] <= Knots[i-1]) THEN
      Result := FALSE;
      RETURN(Result);
    END_IF;
    K := KnotMult[i];
    IF (i < UpKnots) AND (K > Degree) THEN
      Result := FALSE;
      RETURN(Result);
    END_IF;
    IF (i = UpKnots) AND (K > Degree + 1) THEN
      Result := FALSE;
      RETURN(Result);
    END_IF;
  END_REPEAT;
 
  RETURN(Result);
 
END_FUNCTION;

8.9.6.6.3 References

• IfcBSplineCurveWithKnots
• IfcBSplineSurfaceWithKnots