-- File:	GeomFill_Darboux.cdl
-- Created:	Wed Mar  4 11:57:03 1998
-- Author:	Roman BORISOV
--		<rbv@ecolox.nnov.matra-dtv.fr>
---Copyright:	 Matra Datavision 1998


class Darboux from GeomFill 
              inherits TrihedronLaw  from  GeomFill 
	 
          ---Purpose: Defines Darboux case of Frenet Trihedron Law

uses

 HSurface from  Adaptor3d,
 Shape  from  GeomAbs, 
 Array1OfReal   from TColStd, 
 Vec    from  gp,  
 HArray1OfReal from TColStd, 
 CurveOnSurface from Adaptor3d 
 
raises
 OutOfRange,  ConstructionError

is  
   Create  
      returns Darboux from GeomFill 
      raises  ConstructionError; 
    
   Copy(me)   
   returns  TrihedronLaw  from  GeomFill          
   is  redefined;
     
-- 
-- 
--========== To compute Location and derivatives Location
--              
   D0(me : mutable; 
      Param: Real; 
      Tangent    : out  Vec  from  gp; 
      Normal     : out  Vec  from  gp; 
      BiNormal   : out  Vec  from  gp)
      ---Purpose: compute Triedrhon on curve at parameter <Param>         
   returns Boolean  is  redefined;
	
   D1(me : mutable;
      Param: Real;       
      Tangent    : out  Vec  from  gp;  
      DTangent   : out  Vec  from  gp; 
      Normal     : out  Vec  from  gp; 
      DNormal    : out  Vec  from  gp;                 
      BiNormal   : out  Vec  from  gp; 
      DBiNormal  : out  Vec  from  gp)
      ---Purpose: compute Triedrhon and  derivative Trihedron  on curve
      --          at parameter <Param>                
      --  Warning : It used only for C1 or C2 aproximation
   returns Boolean  
   is  redefined; 
   
   D2(me : mutable;
      Param: Real;       
      Tangent    : out  Vec  from  gp;  
      DTangent   : out  Vec  from  gp; 
      D2Tangent  : out  Vec  from  gp; 
      Normal     : out  Vec  from  gp; 
      DNormal    : out  Vec  from  gp;                 
      D2Normal   : out  Vec  from  gp; 
      BiNormal   : out  Vec  from  gp; 
      DBiNormal  : out  Vec  from  gp; 
      D2BiNormal : out  Vec  from  gp)    
      ---Purpose: compute  Trihedron on curve          
      --          first and seconde  derivatives.
      --  Warning : It used only for C2 aproximation
   returns Boolean
   is  redefined; 
--
--  =================== Management  of  continuity  ===================
--                 
   NbIntervals(me; S : Shape from GeomAbs) 
	---Purpose: Returns  the number  of  intervals for  continuity
	--          <S>. 
        --          May be one if Continuity(me) >= <S>
   returns Integer  is  redefined;

   Intervals(me; T : in out Array1OfReal from TColStd; 
    	         S : Shape from GeomAbs)
	---Purpose: Stores in <T> the  parameters bounding the intervals
	--          of continuity <S>.
	--          
	--          The array must provide  enough room to  accomodate
	--          for the parameters. i.e. T.Length() > NbIntervals()
    raises
    	OutOfRange from Standard 
    is redefined;  
     
	  
--  ===================  To help   computation of  Tolerance   ===============	 
    GetAverageLaw(me  :  mutable;
      ATangent    : out  Vec  from  gp; 
      ANormal     : out  Vec  from  gp; 
      ABiNormal   : out  Vec  from  gp) 
     ---Purpose: Get average value of Tangent(t) and Normal(t) it is usfull to 
     --          make fast approximation of rational  surfaces.        
  is  redefined;

--   =================== To help Particular case   ===============	
   
    IsConstant(me) 
    ---Purpose: Say if the law is Constant.        
    returns  Boolean   
    is redefined;
 
   IsOnlyBy3dCurve(me) 
     ---Purpose: Return False.        
    returns  Boolean   
    is redefined;  

end Darboux;