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

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


Copyright (c) 1993-2001 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
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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
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=========================================================================*/
// .NAME vtkAbstractPicker - define API for picking subclasses
// .SECTION Description
// vtkAbstractPicker is an abstract superclass that defines a minimal API
// for its concrete subclasses. The minimum functionality of a picker is
// to return the x-y-z global coordinate position of a pick (the pick
// itself is defined in display coordinates).
//
// The API to this class is to invoke the Pick() method with a selection
// point (in display coordinates - pixels) and a renderer. Then get the
// resulting pick position in global coordinates with the GetPickPosition()
// method.
//
// vtkPicker has hooks for methods to call during the picking process.  These
// methods are StartPickMethod(), PickMethod(), and EndPickMethod() which are
// invoked prior to picking, when something is picked, and after all picking
// candidates have been tested. Note that during the pick process the
// PickMethod() of vtkProp (and its subclasses such as vtkActor) is called
// prior to the pick method of vtkPicker.

// .SECTION Caveats
// vtkAbstractPicker and its subclasses will not pick props that are 
// "unpickable" (see vtkProp) or are fully transparent (if transparency
// is a property of the vtkProp).
//
// There are two classes of pickers: those that pick using geometric methods
// (typically a ray cast); and those that use rendering hardware. Geometric
// methods return more information but are slower. Hardware methods are much
// faster and return minimal information. Examples of geometric pickers
// include vtkPicker, vtkCellPicker, and vtkPointPicker. Examples of hardware
// pickers include vtkWorldPointPicker and vtkPropPicker.

// .SECTION See Also
// vtkPropPicker uses hardware acceleration to pick an instance of vtkProp.
// (This means that 2D and 3D props can be picked, and it's relatively fast.)
// If you need to pick cells or points, you might wish to use vtkCellPicker
// or vtkPointPicker. vtkWorldPointPicker is the fastest picker, returning
// an x-y-z coordinate value using the hardware z-buffer. vtkPicker can be
// used to pick the bounding box of 3D props.

#ifndef __vtkAbstractPicker_h
#define __vtkAbstractPicker_h

#include "vtkObject.h"
#include "vtkRenderer.h"

class VTK_EXPORT vtkAbstractPicker : public vtkObject
{
public:
  vtkTypeMacro(vtkAbstractPicker,vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Get the renderer in which pick event occurred.
  vtkGetObjectMacro(Renderer,vtkRenderer);

  // Description:
  // Get the selection point in screen (pixel) coordinates. The third
  // value is related to z-buffer depth. (Normally should be =0.)
  vtkGetVectorMacro(SelectionPoint,float,3);

  // Description:
  // Return position in global coordinates of pick point.
  vtkGetVectorMacro(PickPosition,float,3);

  // Description:
  // Perform pick operation with selection point provided. Normally the 
  // first two values for the selection point are x-y pixel coordinate, and
  // the third value is =0. Return non-zero if something was successfully 
  // picked.
  virtual int Pick(float selectionX, float selectionY, float selectionZ, 
		   vtkRenderer *renderer) = 0;

  // Description: Perform pick operation with selection point
  // provided. Normally the first two values for the selection point
  // are x-y pixel coordinate, and the third value is =0. Return
  // non-zero if something was successfully picked.
  int Pick(float selectionPt[3], vtkRenderer *ren)
    {return this->Pick(selectionPt[0],selectionPt[1],selectionPt[2],ren);};  

  // Description: Specify function to be called as picking operation
  // begins.
  void SetStartPickMethod(void (*f)(void *), void *arg);

  // Description:
  // Specify function to be called when something is picked.
  void SetPickMethod(void (*f)(void *), void *arg);

  // Description:
  // Specify function to be called after all picking operations have been
  // performed.
  void SetEndPickMethod(void (*f)(void *), void *arg);

  // Description:
  // Set a method to delete user arguments for StartPickMethod.
  void SetStartPickMethodArgDelete(void (*f)(void *));

  // Description:
  // Set a method to delete user arguments for PickMethod.
  void SetPickMethodArgDelete(void (*f)(void *));

  // Description:
  // Set a method to delete user arguments for EndPickMethod.
  void SetEndPickMethodArgDelete(void (*f)(void *));

  // Description:
  // Use these methods to control whether to limit the picking to this list
  // (rather than renderer's actors). Make sure that the pick list contains 
  // actors that referred to by the picker's renderer.
  vtkSetMacro(PickFromList,int);
  vtkGetMacro(PickFromList,int);
  vtkBooleanMacro(PickFromList,int);

  // Description:
  // Initialize list of actors in pick list.
  void InitializePickList();

  // Description:
  // Add an actor to the pick list.
  void AddPickList(vtkProp *);

  // Description:
  // Delete an actor from the pick list.
  void DeletePickList(vtkProp *);
  
  // Description:
  // Return the list of actors in the PickList.
  vtkPropCollection *GetPickList() {return this->PickList;}

protected:
  vtkAbstractPicker();
  ~vtkAbstractPicker();
  vtkAbstractPicker(const vtkAbstractPicker&) {};
  void operator=(const vtkAbstractPicker&) {};

  virtual void Initialize();

  vtkRenderer *Renderer; //pick occurred in this renderer's viewport
  float SelectionPoint[3]; //selection point in window (pixel) coordinates
  float PickPosition[3]; //selection point in world coordinates
  
  // the following are used to manage invocation of pick methods
  void (*StartPickMethod)(void *);
  void (*StartPickMethodArgDelete)(void *);
  void *StartPickMethodArg;
  void (*PickMethod)(void *);
  void *PickMethodArg;
  void (*PickMethodArgDelete)(void *);
  void (*EndPickMethod)(void *);
  void (*EndPickMethodArgDelete)(void *);
  void *EndPickMethodArg;
  
  // use the following to control picking from a list
  int PickFromList;
  vtkPropCollection *PickList;
};

#endif


