-- File:	FairCurve_MinimalVariation.cdl
-- Created:	Mon Feb 26 13:54:16 1996
-- Author:	Philippe MANGIN
--		<pmn@sgi29>
---Copyright:	 Matra Datavision 1996


class MinimalVariation from FairCurve inherits Batten from FairCurve

	---Purpose: Computes a 2D curve using an algorithm which
    	-- minimizes tension, sagging, and jerk energy. As in
    	-- FairCurve_Batten, two reference points are used.
    	-- Unlike that class, FairCurve_MinimalVariation
    	-- requires curvature settings at the first and second
    	-- reference points. These are defined by the rays of
    	-- curvature desired at each point.

uses Pnt2d from gp,
     Vec2d from gp,
     AnalysisCode from FairCurve

raises NegativeValue, NullValue, DomainError

is
    Create (P1,P2 : Pnt2d; Heigth : Real; Slope : Real = 0; PhysicalRatio  :  Real  =  0)

  	---Purpose: Constructs the two contact points P1 and P2  and the geometrical
    	--          characteristics of the batten (elastic beam)  
    	--   These include the real number values for height of
    	-- deformation Height, slope value Slope, and kind of
    	-- energy PhysicalRatio. The kinds of energy include:
    	-- -   Jerk (0)
    	-- -   Sagging (1).
    	-- Note that the default setting for Physical Ration is in FairCurve_Batten
        --          Other parameters are initialized as follow :
    	--           - FreeSliding = False
    	--           - ConstraintOrder1 = 1
    	--           - ConstraintOrder2 = 1 
    	--           - Angle1 = 0
    	--           - Angle2 = 0
    	--           - Curvature1 = 0
    	--           - Curvature2 = 0
    	--           - SlidingFactor = 1
        -- Warning
    	-- If PhysicalRatio equals 1, you cannot impose constraints on curvature.
    	-- Exceptions
    	-- NegativeValue if Height is less than or equal to 0.
    	-- NullValue if the distance between P1 and P2 is less
    	-- than or equal to the tolerance value for distance in
    	-- Precision::Confusion: P1.IsEqual(P2,
    	-- Precision::Confusion()). The function
    	-- gp_Pnt2d::IsEqual tests to see if this is the case.
    returns MinimalVariation
    raises  NegativeValue,
   	    NullValue;    
    
    
--      Definition Methods   ------------------------------------
--  
    ---Purpose:  Definition of the geometricals constraints
   
    SetCurvature1 (me : in out; Curvature : Real);
    	---C++: inline
    	---Purpose: Allows you to set a new constraint on curvature at the first point.

    SetCurvature2 (me : in out; Curvature : Real);
    	---C++: inline
    	---Purpose: Allows you to set a new constraint on curvature at the second point.
    	--      
    SetPhysicalRatio (me : in out; Ratio : Real)
    	---C++: inline
    	---Purpose:  Allows you to set the physical ratio Ratio.
    	-- The kinds of energy which you can specify include:
    	--          0 is only "Jerk" Energy
    	--          1 is only "Sagging" Energy like batten
        --  Warning: if Ratio is 1 it is impossible to impose curvature constraints.
    	--  Raises  DomainError if Ratio < 0 or Ratio > 1
     raises  DomainError; 
     

    Compute (me :in out;  
    	     ACode : in out  AnalysisCode;
    	     NbIterations : Integer = 50;  
    	     Tolerance    : Real = 1.0e-3 )
    	---Purpose: Computes the curve with respect to the constraints,
    	-- NbIterations and Tolerance. The tolerance setting
    	-- allows you to control the precision of computation, and
    	-- the maximum number of iterations allows you to set a limit on computation time.
     returns Boolean
     is redefined; 
	
     Compute (me :in out;
             DeltaP1 : Vec2d;
	     DeltaP2 : Vec2d;
	     DeltaAngle1 : Real;
	     DeltaAngle2 : Real;
	     DeltaCurvature1 : Real;
	     DeltaCurvature2 : Real;
    	     ACode : in out  AnalysisCode;
    	     NbIterations : Integer;  
    	     Tolerance: Real )
    	---Purpose: compute the curve with respect of the delta-constraints.
    returns Boolean is private;
   
    GetCurvature1  (me)
    	---C++: inline
    	---Purpose: Returns the first established curvature.
    returns  Real;
    
    GetCurvature2  (me)
       	---C++: inline
 	---Purpose: Returns the second established curvature.
    returns  Real; 
    
    GetPhysicalRatio(me)
    	---C++: inline
    	---Purpose       : Returns the physical ratio, or kind of energy.
    returns  Real;    
    
    Dump(me ; o : in out OStream)
        ---Purpose: Prints on the stream o information on the current state 
    	--          of the object.
    	--          Is used to redefine the operator <<.	
    is redefined;
    
fields
   OldCurvature1 : Real; 
   OldCurvature2 : Real;
   OldPhysicalRatio : Real;
   NewCurvature1 : Real;
   NewCurvature2 : Real;
   NewPhysicalRatio : Real;
end MinimalVariation;