-- File:	Geom_Ellipse.cdl
-- Created:	Wed Mar 10 09:43:26 1993
-- Author:	JCV
--		<fid@phylox>
-- Copyright:	 Matra Datavision 1993


class Ellipse from Geom inherits Conic from Geom


        ---Purpose :  Describes an ellipse in 3D space.
    	-- An ellipse is defined by its major and minor radii and,
    	-- as with any conic curve, is positioned in space with a
    	-- right-handed coordinate system (gp_Ax2 object) where:
    	-- - the origin is the center of the ellipse,
    	-- - the "X Direction" defines the major axis, and
    	-- - the "Y Direction" defines the minor axis.
    	-- The origin, "X Direction" and "Y Direction" of this
    	-- coordinate system define the plane of the ellipse. The
    	-- coordinate system is the local coordinate system of the ellipse.
    	-- The "main Direction" of this coordinate system is the
    	-- vector normal to the plane of the ellipse. The axis, of
    	-- which the origin and unit vector are respectively the
    	-- origin and "main Direction" of the local coordinate
	-- system, is termed the "Axis" or "main Axis" of the ellipse.
    	-- The "main Direction" of the local coordinate system
    	-- gives an explicit orientation to the ellipse (definition of
    	-- the trigonometric sense), determining the direction in
    	-- which the parameter increases along the ellipse.
    	-- The Geom_Ellipse ellipse is parameterized by an angle:
    	-- P(U) = O + MajorRad*Cos(U)*XDir + MinorRad*Sin(U)*YDir
    	-- where:
    	-- - P is the point of parameter U,
    	-- - O, XDir and YDir are respectively the origin, "X
    	--   Direction" and "Y Direction" of its local coordinate system,
    	-- - MajorRad and MinorRad are the major and minor radii of the ellipse.
    	-- The "X Axis" of the local coordinate system therefore
    	-- defines the origin of the parameter of the ellipse.
    	-- An ellipse is a closed and periodic curve. The period
    	-- is 2.*Pi and the parameter range is [ 0, 2.*Pi [.
      

uses Ax1      from gp,
     Ax2      from gp,
     Elips    from gp,
     Pnt      from gp,
     Trsf     from gp,
     Vec      from gp,
     Geometry from Geom


raises ConstructionError from Standard,
       RangeError        from Standard


is

  Create (E : Elips)  returns mutable Ellipse;
        ---Purpose : Constructs an ellipse by conversion of the gp_Elips ellipse E.

  Create (A2 : Ax2; MajorRadius, MinorRadius : Real)
     returns mutable Ellipse
	---Purpose : Constructs an ellipse
    	--	defined by its major and minor radii, MajorRadius
    	--   and MinorRadius, where A2 locates the ellipse
    	--   and defines its orientation in 3D space such that:
    	--   - the center of the ellipse is the origin of A2,
    	--   - the "X Direction" of A2 defines the major axis
    	--    of the ellipse, i.e. the major radius
    	--    MajorRadius is measured along this axis,
    	--   - the "Y Direction" of A2 defines the minor axis
    	--    of the ellipse, i.e. the minor radius
    	--    MinorRadius is measured along this axis,
    	--   - A2 is the local coordinate system of the ellipse.
    	--        Exceptions
    	-- Standard_ConstructionError if:
    	-- - MajorRadius is less than MinorRadius, or
    	-- - MinorRadius is less than 0.
    	--  Warning The Geom package does not prevent the
    	-- construction of an ellipse where MajorRadius and
    	-- MinorRadius are equal.
     raises ConstructionError;
	


  SetElips (me : mutable; E : Elips)
        ---Purpose: Converts the gp_Elips ellipse E into this ellipse.
       is static;


  SetMajorRadius (me : mutable; MajorRadius : Real)
     raises ConstructionError
    	---Purpose : Assigns a value to the major radius of this ellipse.
    	--       ConstructionError raised if MajorRadius < MinorRadius.
  is static;


  SetMinorRadius (me : mutable; MinorRadius : Real)
     raises ConstructionError
    	---Purpose : Assigns a value to the minor radius of this ellipse.
    	--  ConstructionError raised if MajorRadius < MinorRadius or if MinorRadius < 0.
  is static;
  

  Elips (me)  returns Elips
        ---Purpose :
        --  returns the non transient ellipse from gp with the same 
  is static;
  

  ReversedParameter(me; U : Real) returns Real is redefined static;
  	---Purpose: Computes the parameter on the reversed ellipse for
    	--  the point of parameter U on this ellipse.
    	--  For an ellipse, the returned value is: 2.*Pi - U.


  Directrix1 (me)   returns Ax1
        ---Purpose :
        --  This directrix is the line normal to the XAxis of the ellipse
        --  in the local plane (Z = 0) at a distance d = MajorRadius / e 
        --  from the center of the ellipse, where e is the eccentricity of
        --  the ellipse.
        --  This line is parallel to the "YAxis". The intersection point
        --  between directrix1 and the "XAxis" is the "Location" point
        --  of the directrix1. This point is on the positive side of 
        --  the "XAxis".
     raises ConstructionError;
	---Purpose : Raised if Eccentricity = 0.0. (The ellipse degenerates
	--  into a circle)


  Directrix2 (me)   returns Ax1
        ---Purpose :
        --  This line is obtained by the symmetrical transformation 
        --  of "Directrix1" with respect to the "YAxis" of the ellipse.
    raises ConstructionError;
	---Purpose :
	--  Raised if Eccentricity = 0.0. (The ellipse degenerates into a
	--  circle).
 

  Eccentricity (me)   returns Real is redefined static;
	---Purpose :
	--  Returns the eccentricity of the ellipse  between 0.0 and 1.0
	--  If f is the distance between the center of the ellipse and
	--  the Focus1 then the eccentricity e = f / MajorRadius.
	--  Returns 0 if MajorRadius = 0


  Focal (me)   returns Real;
	---Purpose :
	--  Computes the focal distance. It is the distance between the
        --  the two focus of the ellipse.


  Focus1 (me)   returns Pnt;
	---Purpose :
	--  Returns the first focus of the ellipse. This focus is on the
        --  positive side of the "XAxis" of the ellipse.


  Focus2 (me)   returns Pnt;
        ---Purpose :
	--  Returns the second focus of the ellipse. This focus is on
	--  the negative side of the "XAxis" of the ellipse.


  MajorRadius (me)  returns Real;
    	---Purpose: Returns the major  radius of this ellipse.

  MinorRadius (me)  returns Real;
    	---Purpose: Returns the minor radius of this ellipse.

  Parameter (me)   returns Real;
        ---Purpose :
        --  Returns p = (1 - e * e) * MajorRadius where e is the eccentricity 
        --  of the ellipse.
	--  Returns 0 if MajorRadius = 0


  FirstParameter (me)   returns Real is redefined static;
    	---Purpose : Returns the value of the first parameter of this
    	-- ellipse. This is respectively:
    	-- - 0.0, which gives the start point of this ellipse, or
    	--  The start point and end point of an ellipse are coincident.


  LastParameter (me)  returns Real is redefined static;
    	---Purpose : Returns the value of the  last parameter of this
    	-- ellipse. This is respectively:
    	-- - 2.*Pi, which gives the end point of this ellipse.
    	--  The start point and end point of an ellipse are coincident.


  IsClosed (me)  returns Boolean is redefined static;
        ---Purpose : return True.


  IsPeriodic (me)  returns Boolean is redefined static;
        ---Purpose : return True.



  D0(me; U : Real; P : out Pnt) is redefined static;
	---Purpose: Returns in P the point of parameter U.  	
        --  P = C + MajorRadius * Cos (U) * XDir + MinorRadius * Sin (U) * YDir
        --  where C is the center of the ellipse , XDir the direction of
        --  the "XAxis" and "YDir" the "YAxis" of the ellipse.



  D1 (me; U : Real; P : out Pnt; V1 : out Vec) is redefined static;
        -- Purpose :
        -- Returns the point P of parameter U and the first derivative 
        -- at this point.


  D2 (me; U : Real; P : out Pnt; V1, V2 : out Vec) is redefined static;
        ---Purpose :
        --  Returns the point P of parameter U. The vectors V1 and V2 
        --  are the first and second derivatives at this point.


  D3 (me; U : Real; P : out Pnt; V1, V2, V3 : out Vec) is redefined static;
        ---Purpose :
        --  Returns the point P of parameter U, the first second and
        --  third derivatives V1 V2 and V3.


  DN (me; U : Real; N : Integer)  returns Vec
        ---Purpose : For the point of parameter U of this ellipse, computes
    	-- the vector corresponding to the Nth derivative.
    	-- Exceptions Standard_RangeError if N is less than 1.
    raises RangeError 
    is redefined static;

  Transform (me : mutable; T : Trsf) is redefined static;

    	---Purpose: Applies the transformation T to this ellipse.

  Copy (me)  returns mutable like me is redefined static;
     
    	---Purpose: Creates a new object which is a copy of this ellipse.

fields

     majorRadius : Real;
     minorRadius : Real;

end;