/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkLight.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$


Copyright (c) 1993-1998 Ken Martin, Will Schroeder, Bill Lorensen.

This software is copyrighted by Ken Martin, Will Schroeder and Bill Lorensen.
The following terms apply to all files associated with the software unless
explicitly disclaimed in individual files. This copyright specifically does
not apply to the related textbook "The Visualization Toolkit" ISBN
013199837-4 published by Prentice Hall which is covered by its own copyright.

The authors hereby grant permission to use, copy, and distribute this
software and its documentation for any purpose, provided that existing
copyright notices are retained in all copies and that this notice is included
verbatim in any distributions. Additionally, the authors grant permission to
modify this software and its documentation for any purpose, provided that
such modifications are not distributed without the explicit consent of the
authors and that existing copyright notices are retained in all copies. Some
of the algorithms implemented by this software are patented, observe all
applicable patent law.

IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY DERIVATIVES THEREOF,
EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE IS PROVIDED ON AN
"AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE
MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.


=========================================================================*/
// .NAME vtkLight - a virtual light for 3D rendering
// .SECTION Description
// vtkLight is a virtual light for 3D rendering. It provides methods to locate
// and point the light, turn it on and off, and set its brightness and color.
// In addition to the basic infinite distance point light source attributes,
// you also can specify the light attenuation values and cone angle.
// These attributes are only used if the light is a positional light.
// The default is a directional light (e.g. infinite point light source).

// .SECTION see also
// vtkLightDevice

#ifndef __vtkLight_h
#define __vtkLight_h

#include "vtkReferenceCount.h"

/* need for virtual function */
class vtkRenderer;

class VTK_EXPORT vtkLight : public vtkReferenceCount
{
public:
  vtkLight();
  static vtkLight *New();
  const char *GetClassName() {return "vtkLight";};
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Abstract interface to renderer. Each concrete subclass of vtkLight
  // will load its data into the graphics system in response to this method
  // invocation. The actual loading is performed by a vtkLightDevice
  // subclass, which will get created automatically.
  virtual void Render(vtkRenderer *, int) {};

  // Description:
  // Set/Get the color of the light.
  vtkSetVector3Macro(Color,float);
  vtkGetVectorMacro(Color,float,3);

  // Description:
  // Set/Get the position of the light.
  vtkSetVector3Macro(Position,float);
  vtkGetVectorMacro(Position,float,3);

  // Description:
  // Set/Get the point at which the light is shining.
  vtkSetVector3Macro(FocalPoint,float);
  vtkGetVectorMacro(FocalPoint,float,3);

  // Description:
  // Set/Get the brightness of the light (from one to zero).
  vtkSetMacro(Intensity,float);
  vtkGetMacro(Intensity,float);

  // Description:
  // Turn the light on or off.
  vtkSetMacro(Switch,int);
  vtkGetMacro(Switch,int);
  vtkBooleanMacro(Switch,int);

  // Description:
  // Turn positional lighting on or off.
  vtkSetMacro(Positional,int);
  vtkGetMacro(Positional,int);
  vtkBooleanMacro(Positional,int);

  // Description:
  // Set/Get the exponent of the cosine used in positional lighting.
  vtkSetMacro(Exponent,float);
  vtkGetMacro(Exponent,float);

  // Description:
  // Set/Get the lighting cone angle of a positional light in degrees.
  // A value of 180 indicates that you want no spot lighting effects
  // just a positional light.
  vtkSetMacro(ConeAngle,float);
  vtkGetMacro(ConeAngle,float);

  // Description:
  // Set/Get the quadratic attenuation constants. They are specified as
  // constant, linear, and quadratic, in that order.
  vtkSetVector3Macro(AttenuationValues,float);
  vtkGetVectorMacro(AttenuationValues,float,3);

protected:
  float FocalPoint[3];
  float Position[3];
  float Intensity;
  float Color[3];
  int   Switch;
  int   Positional;
  float Exponent;
  float ConeAngle;
  float AttenuationValues[3];
};

#endif
