-- File:	Vrml_SpotLight.cdl
-- Created:	Wed Feb 12 11:19:05 1997
-- Author:	Alexander BRIVIN
--		<brivin@meteox.nizhny.matra-dtv.fr>
---Copyright:	 Matra Datavision 1997


class SpotLight from Vrml 

	---Purpose: specifies a spot light node of VRML nodes specifying
	--         properties of lights. 
    	--  This  node  defines  a  spotlight  light  source.
    	--  A  spotlight  is  placed  at  a  fixed  location  in  3D-space 
    	--  and  illuminates in  a  cone  along  a  particular  direction.   
    	--  The  intensity  of  the  illumination  drops  off  exponentially   
    	--  as  a  ray  of  light  diverges  from  this  direction  toward   
    	--  the  edges  of  cone. 
	--  The  rate  of  drop-off  and  agle  of  the  cone  are  controlled   
    	--  by  the  dropOfRate  and  cutOffAngle
    	--  Color is  written  as  an  RGB  triple.
    	--  Light intensity must be in the range 0.0 to 1.0, inclusive. 

uses
    Color   from Quantity, 
    Vec     from gp
is
                                                    --  defaults  :
    Create returns SpotLight from Vrml; 
    	    	    	    	    	    	    --  myOnOff(Standard_True)
 						    --  myIntensity(1)
						    --  myColor(1 1 1)
						    --  myLocation(0 0 1)
						    --  myDirection(0 0 -1)
    	    	    	    	    	    	    --  myDropOffRate(0) 
    	    	    	    	    	    	    --  myCutOffAngle(0.785398) 

    Create  ( aOnOff        :  Boolean from  Standard; 
    	      aIntensity    :  Real    from  Standard; 
    	      aColor        :  Color   from  Quantity; 
    	      aLocation     :  Vec     from  gp;
    	      aDirection    :  Vec     from  gp; 
    	      aDropOffRate  :  Real    from  Standard; 
    	      aCutOffAngle  :  Real    from  Standard  )
    	returns SpotLight from Vrml; 
   
    SetOnOff ( me : in out;  anOnOff : Boolean from  Standard );
    OnOff ( me )  returns Boolean  from  Standard;

    SetIntensity ( me : in out;  aIntensity : Real from  Standard );
    Intensity ( me )  returns Real  from  Standard;

    SetColor ( me : in out;  aColor :  Color   from  Quantity );
    Color ( me )  returns  Color   from  Quantity;

    SetLocation ( me : in out;  aLocation : Vec  from  gp );
    Location ( me )  returns Vec  from  gp;
    
    SetDirection ( me : in out;  aDirection : Vec  from  gp );
    Direction ( me )  returns Vec  from  gp;

    SetDropOffRate ( me : in out;  aDropOffRate : Real from  Standard );
    DropOffRate ( me )  returns Real  from  Standard;
    
    SetCutOffAngle ( me : in out;  aCutOffAngle : Real from  Standard );
    CutOffAngle ( me )  returns Real  from  Standard;

    Print  ( me;  anOStream: in out OStream from Standard) returns OStream from Standard; 
    ---C++:  return  & 
    
fields
 
    myOnOff        :  Boolean from  Standard; -- Whether light is on
    myIntensity    :  Real    from  Standard; -- Source intensity (0 to 1)
    myColor        :  Color   from  Quantity; -- RGB source color
    myLocation     :  Vec     from  gp;       -- Source location
    myDirection    :  Vec     from  gp;       -- Primary direction of illumination
    myDropOffRate  :  Real    from  Standard; -- Rate of intensity drop-off from primary
                                              -- direction: 0 = constant intensity,
                                              --            1 = sharp drop-off
    myCutOffAngle  :  Real    from  Standard; -- Angle (in radians) outside of which
    	    	    	    	    	      -- intensity is zero, measured from 
    	    	    	    	    	      -- edge of cone to other edge
end SpotLight;