-- File:	ExtPElC.cdl
-- Created:	Thu Feb 21 18:03:14 1991
-- Author:	Isabelle GRIGNON
--		<isg@topsn3>
---Copyright:	 Matra Datavision 1991


class   ExtPElC from Extrema 
    	---Purpose: It calculates all the distances between a point
    	--          and an elementary curve.
    	--          These distances can be minimum or maximum.

uses    POnCurv from Extrema,
        Lin     from gp,
    	Circ    from gp,
    	Elips   from gp,
    	Hypr    from gp,
    	Parab   from gp,
    	Pnt     from gp

raises  NotDone     from StdFail,
    	OutOfRange  from Standard

is
    Create returns ExtPElC;

    Create (P: Pnt; C: Lin; Tol: Real; Uinf,Usup: Real)
    	returns ExtPElC;
    	---Purpose: Calculates the extremum distance between the
    	--          point P and the segment [Uinf,Usup] of the line C.

    Perform(me: in out; P: Pnt; C: Lin; Tol: Real; Uinf,Usup: Real)
    is static;


    Create (P: Pnt; C: Circ; Tol: Real; Uinf,Usup: Real)
    	returns ExtPElC;
    	---Purpose: Calculates the 2 extremum distances between the
    	--          point P and the segment [Uinf,Usup] of the circle C.
    	--          Tol is used to determine
    	--          if P is on the axis of the circle or
    	--          if an extremum is on an endpoint of the segment.
    	--          If P is on the axis of the circle,
    	--          there are infinite solution then IsDone(me)=False.
    	--          The conditions on the Uinf and Usup are:
    	--            0. <= Uinf <= 2.*PI and Usup > Uinf.
    	--          If Usup > Uinf + 2.*PI, then only the solutions in
    	--          the range [Uinf,Uinf+2.*PI[ are computed.


    Perform(me: in out; P: Pnt; C: Circ; Tol: Real; Uinf,Usup: Real)
    is static;

    Create (P: Pnt; C: Elips; Tol: Real; Uinf,Usup: Real)
    	returns ExtPElC;
    	---Purpose: Calculates the 4 extremum distances between the
    	--          point P and the segment [Uinf,Usup] of the elipse C.
     	--          Tol is used to determine
     	--          if the point is on the axis of the elipse and
     	--          if the major radius is equal to the minor radius or
     	--          if an extremum is on an endpoint of the segment.
    	--          If P is on the axis of the elipse,
    	--          there are infinite solution then IsDone(me)=False.
    	--          The conditions on the Uinf and Usup are:
    	--            0. <= Uinf <= 2.*PI and Usup > Uinf.
    	--          If Usup > Uinf + 2.*PI, then only the solutions in
    	--          the range [Uinf,Uinf+2.*PI[ are computed.


    Perform(me: in out; P: Pnt; C: Elips; Tol: Real; Uinf,Usup: Real)
    is static;

    Create (P: Pnt; C: Hypr; Tol: Real; Uinf,Usup: Real)
    	returns ExtPElC;
    	---Purpose: Calculates the extremum distances between the
    	--          point P and the segment [Uinf,Usup] of the hyperbola
    	--          C.
    	--          Tol is used to determine if two solutions u and v
    	--          are identical; the condition is:
    	--          dist(C(u),C(v)) < Tol.

    Perform(me: in out; P: Pnt; C: Hypr; Tol: Real; Uinf,Usup: Real)
    is static;

    Create (P: Pnt; C: Parab; Tol: Real; Uinf,Usup: Real)
    	returns ExtPElC;
    	---Purpose: Calculates the 4 extremum distances between the
    	--          point P and the segment [Uinf,Usup] of the parabola
    	--          C.
    	--          Tol is used to determine if two solutions u and v
    	--          are identical; the condition is:
    	--          dist(C(u),C(v)) < Tol.

    Perform(me: in out; P: Pnt; C: Parab; Tol: Real; Uinf,Usup: Real)
    is static;
    

    IsDone (me) returns Boolean
    	---Purpose: True if the distances are found.
    	is static;

    NbExt (me) returns Integer
    	---Purpose: Returns the number of extremum distances.
	raises  NotDone from StdFail
	    	-- if IsDone(me)=False.
    	is static;
    
    SquareDistance (me; N: Integer) returns Real
    	---Purpose: Returns the value of the Nth extremum square distance.
    	raises  NotDone from StdFail,
	    	-- if IsDone(me)=False.
    	    	OutOfRange
	    	-- if N < 1 or N > NbPoints(me).
    	is static;

    IsMin (me; N: Integer) returns Boolean
    	---Purpose: Returns True if the Nth extremum distance is a
    	--          minimum.
    	raises  NotDone from StdFail,
	    	-- if IsDone(me)=False.
    	    	OutOfRange
	    	-- if N < 1 or N > NbPoints(me).
    	is static;

    Point (me; N: Integer) returns POnCurv
    	---Purpose: Returns the point of the Nth extremum distance.
    	raises  NotDone from StdFail,
	    	-- if IsDone(me)=False.
    	    	OutOfRange
	    	-- if N < 1 or N > NbPoints(me).
    	is static;

fields
    myDone : Boolean;
    myNbExt: Integer;
    mySqDist: Real [4];
    myIsMin: Boolean [4];
    myPoint: POnCurv from Extrema [4];

end ExtPElC;