-- File:	Circ2dBisec.cdl
-- Created:	Wed Apr  3 11:29:37 1991
-- Author:	Remi GILET
--		<reg@topsn2>
---Copyright:	 Matra Datavision 1991

class Circ2dBisec

from GccAna

	---Purpose: This class describes functions for building bisecting curves between two 2D circles.
    	-- A bisecting curve between two circles is a curve such
    	-- that each of its points is at the same distance from the
    	-- two circles. It can be an ellipse, hyperbola, circle or line,
    	-- depending on the relative position of the two circles.
    	-- The algorithm computes all the elementary curves which
    	-- are solutions. There is no solution if the two circles are coincident.
    	-- A Circ2dBisec object provides a framework for:
    	-- -   defining the construction of the bisecting curves,
    	-- -   implementing the construction algorithm, and consulting the result.

uses Circ2d from gp,
     Bisec  from GccInt

raises OutOfRange        from Standard,
       NotDone           from StdFail

is

Create(Circ1,Circ2 : Circ2d from gp) returns Circ2dBisec;

    	---Purpose: Constructs bisecting curves between the two circles Circ1 and Circ2.
        
IsDone(me) returns Boolean from Standard
is static;
    	---Purpose: This method returns True if the construction algorithm succeeded.

NbSolutions(me) returns Integer from Standard
    	---Purpose: This method returns the number of solutions.
    	--    Raises NotDone if the construction algorithm  didn't succeed.
raises NotDone
is static;
  

ThisSolution(me                           ; 
    	     Index : Integer from Standard) returns Bisec from GccInt
    	---Purpose: Returns the solution number Index 
    	-- Raises OutOfRange exception if Index is greater than 
    	--          the number of solutions.
    	--          It raises NotDone if the construction algorithm
        --          didn't succeed.
raises OutOfRange, NotDone
is static;
   
fields

    WellDone : Boolean from Standard;
    	---Purpose: True if the algorithm succeeded.

    NbrSol   : Integer from Standard;
    	---Purpose: The number of possible solutions.

    intersection : Integer from Standard;
    	---Purpose: c is the circle which has the lowest radius among Circ1 and 
    	--          Circ2, and C is the other one.
    	--          intersection = 0 if c is completly inside C.
    	--          intersection = 1 if c is tangent to C and c is inside C.
    	--          intersection = 2 if c intersects C.
    	--          intersection = 3 if c is tangent to C and c is outside C.
    	--          intersection = 4 if c is completly outside C.

    sameradius : Boolean from Standard;
    	---Purpose: sameradius is true is Circ1 has the same radius as Circ2.

    circle1   : Circ2d from gp;
    	---Purpose: The first argument used for ThisSolution. It is the circle 
    	--          which has the greatest radius or Circ1 if Circ1 and Circ2 
    	--          has the same radius.

    circle2   : Circ2d from gp;
    	---Purpose: The second argument used for ThisSolution. It is the other 
    	--          circle.

end Circ2dBisec;