-- Created on: 1991-03-25
-- Created by: Michel CHAUVAT
-- Copyright (c) 1991-1999 Matra Datavision
-- Copyright (c) 1999-2014 OPEN CASCADE SAS
--
-- This file is part of Open CASCADE Technology software library.
--
-- This library is free software; you can redistribute it and / or modify it
-- under the terms of the GNU Lesser General Public version 2.1 as published
-- by the Free Software Foundation, with special exception defined in the file
-- OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
-- distribution for complete text of the license and disclaimer of any warranty.
--
-- Alternatively, this file may be used under the terms of Open CASCADE
-- commercial license or contractual agreement.

generic class CLProps from LProp
                         (Curve as any;
                    	  Vec   as any; -- as Vec or Vec2d
		     	  Pnt   as any; -- as Pnt or Pnt2d
		   	  Dir   as any; -- as Dir or Dir2d
                   	  Tool  as any) -- as ToolCurve(Curve, Pnt, Vec)  

    ---Purpose: Computation of Curve Local Properties:
    --          - point,
    --          - derivatives,
    --          - tangent,
    --          - normal plane,
    --          - curvature,
    --          - normal,
    --          - centre of curvature,

uses    Status from LProp

raises  BadContinuity from LProp, 
        DomainError   from Standard, 
        OutOfRange    from Standard, 
        NotDefined    from LProp
is


    Create(C: Curve; N: Integer; Resolution: Real)
    	---Purpose: Initializes the local properties of the curve <C> 
    	--          The current point and the derivatives are 
    	--          computed at the same time, which allows an 
    	--          optimization of the computation time.
    	--          <N> indicates the maximum number of derivations to 
    	--          be done (0, 1, 2 or 3). For example, to compute 
    	--          only the tangent, N should be equal to 1.
    	--          <Resolution> is the linear tolerance (it is used to test
    	--          if a vector is null).
    	returns CLProps
    	raises OutOfRange;
	    	-- if N < 0 or N > 3.

    Create(C: Curve; U : Real; N: Integer; Resolution: Real)
        --- Purpose : Same as previous constructor but here the parameter is
        --            set to the value <U>.
        --            All the computations done will be related to <C> and <U>.
    	returns CLProps
    	raises OutOfRange;
	    	-- if N < 0 or N > 3.
	    	
    Create(N : Integer;Resolution:Real)
        --- Purpose : Same as previous constructor but here the parameter is
        --            set to the value <U> and the curve is set 
        --            with SetCurve.
        --            the curve can have a empty constructor
        --            All the computations done will be related to <C> and <U>
        --            when the functions "set" will be done.

    returns CLProps
    raises OutOfRange;
    
    SetParameter(me: in out; U : Real)
    	---Purpose: Initializes the local properties of the curve 
    	--          for the parameter value <U>.
	is static;
	    	
    SetCurve(me: in out; C : Curve)
    	---Purpose: Initializes the local properties of the curve 
    	--          for the new curve.
	is static;

    Value(me) returns Pnt is static;
    	---Purpose: Returns the Point.
    	---C++: return const &

    D1(me: in out) returns Vec is static;
    	---Purpose: Returns the first derivative. 
    	--          The derivative is computed if it has not been yet.
    	---C++: return const &

    D2(me: in out) returns Vec is static;
    	---Purpose: Returns the second derivative.
    	--          The derivative is computed if it has not been yet.
    	---C++: return const &

    D3(me: in out) returns Vec is static;
    	---Purpose: Returns the third derivative.
    	--          The derivative is computed if it has not been yet.
    	---C++: return const &

    IsTangentDefined(me: in out) returns Boolean is static;
    	---Purpose: Returns True if the tangent is defined.
    	--          For example, the tangent is not defined if the 
    	--          three first derivatives are all null.

    Tangent(me: in out; D : out Dir)
        ---Purpose: output  the tangent direction <D>
	raises  NotDefined
    	    	-- if IsTangentDefined(me)=False.
    	is static;

    Curvature(me: in out)
    	---Purpose: Returns the curvature.
    	returns Real
	raises  NotDefined
    	    	-- if IsTangentDefined(me) == False.
    	is static;

    Normal(me: in out; N : out Dir)
    	---Purpose: Returns the normal direction <N>.
	raises  NotDefined
	    	-- if Curvature(me) < Resolution
	is static;

    CentreOfCurvature(me: in out; P : out Pnt)
    	---Purpose: Returns the centre of curvature <P>.
	raises  NotDefined
	    	-- if Curvature(me) < Resolution
	is static;

fields

    myCurve      : Curve;    -- the Curve on which thw calculus are done
    myU          : Real;     -- the current value of the parameter
    myDerOrder   : Integer;  -- the order of derivation
    myCN         : Real;     -- the order of continuity of the Curve
    myLinTol     : Real;     -- the tolerance for null Vector
    
    myPnt        : Pnt;      -- the current point value
    myDerivArr   : Vec[3];   -- the current first, second and third derivative
                             -- value
    myTangent    : Dir;      -- the tangent value
    myCurvature  : Real;     -- the curvature value

    myTangentStatus   : Status from LProp; 
                          -- the status of the tangent direction
    mySignificantFirstDerivativeOrder : Integer;
                          -- the order of the first non null derivative
                          -- 
end CLProps;