-- File:	GeomFill_Fixed.cdl
-- Created:	Tue Dec  9 18:33:12 1997
-- Author:	Philippe MANGIN
--		<pmn@sgi29>
---Copyright:	 Matra Datavision 1997


class Fixed from  GeomFill   
inherits TrihedronLaw  from  GeomFill 

	---Purpose: Defined an constant TrihedronLaw         

uses
 Shape  from  GeomAbs, 
 Array1OfReal   from TColStd, 
 Vec    from  gp  
 
raises
 OutOfRange,  ConstructionError
is  

   Create(Tangent,  Normal :  Vec from gp)
   returns  Fixed from  GeomFill  
   raises  ConstructionError;   
    -- if <Tangent> and <Normal> are colinear

   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: Return True.        
    returns  Boolean   
    is redefined;  
     
fields 
    T,  N,  B  :  Vec  from  gp;
end Fixed;