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/*=========================================================================
Program: Visualization Toolkit
Module: $RCSfile: vtkWorldPointPicker.cxx,v $
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
#include "vtkWorldPointPicker.h"
#include "vtkCamera.h"
#include "vtkCommand.h"
#include "vtkObjectFactory.h"
#include "vtkRenderer.h"
vtkCxxRevisionMacro(vtkWorldPointPicker, "$Revision: 1.21 $");
vtkStandardNewMacro(vtkWorldPointPicker);
vtkWorldPointPicker::vtkWorldPointPicker()
{
}
// Perform pick operation with selection point provided. The z location
// is recovered from the zBuffer. Always returns 0 since no actors are picked.
int vtkWorldPointPicker::Pick(double selectionX, double selectionY,
double selectionZ, vtkRenderer *renderer)
{
vtkCamera *camera;
double cameraFP[4];
double display[3], *world;
double *displayCoord;
double z;
// Initialize the picking process
this->Initialize();
this->Renderer = renderer;
this->SelectionPoint[0] = selectionX;
this->SelectionPoint[1] = selectionY;
this->SelectionPoint[2] = selectionZ;
// Invoke start pick method if defined
this->InvokeEvent(vtkCommand::StartPickEvent,NULL);
z = renderer->GetZ ((int) selectionX, (int) selectionY);
// if z is 1.0, we assume the user has picked a point on the
// screen that has not been rendered into. Use the camera's focal
// point for the z value. The test value .999999 has to be used
// instead of 1.0 because for some reason our SGI Infinite Reality
// engine won't return a 1.0 from the zbuffer
if (z < 0.999999)
{
selectionZ = z;
vtkDebugMacro(<< " z from zBuffer: " << selectionZ);
}
else
{
// Get camera focal point and position. Convert to display (screen)
// coordinates. We need a depth value for z-buffer.
camera = renderer->GetActiveCamera();
camera->GetFocalPoint(cameraFP); cameraFP[3] = 1.0;
renderer->SetWorldPoint(cameraFP[0],cameraFP[1],cameraFP[2],cameraFP[3]);
renderer->WorldToDisplay();
displayCoord = renderer->GetDisplayPoint();
selectionZ = displayCoord[2];
vtkDebugMacro(<< "computed z from focal point: " << selectionZ);
}
// now convert the display point to world coordinates
display[0] = selectionX;
display[1] = selectionY;
display[2] = selectionZ;
renderer->SetDisplayPoint (display);
renderer->DisplayToWorld ();
world = renderer->GetWorldPoint ();
for (int i=0; i < 3; i++)
{
this->PickPosition[i] = world[i] / world[3];
}
// Invoke end pick method if defined
this->InvokeEvent(vtkCommand::EndPickEvent,NULL);
return 0;
}
void vtkWorldPointPicker::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os,indent);
}
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