Bug in vtkVoxel.cxx, a great one ;-)

[Alexander Prokop]

Hi all,

Well, my streamlines still did not work correctly.
I found a Bug in vtkVoxel.cxx. That was a great one ;-)
I use VTK version 2.0, but the bug is still there in 
version 2.2. I corrected the bug for 2.0 in the code below. 
For the fixing see the comment CORRECTED

Dipl.-Ing. Alexander Prokop
Development Engineer
CST Computer Simulation Technology GmbH

Email: prokop at temf.tu-darmstadt.de
Web:   http://www.cst.de

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int vtkVoxel::EvaluatePosition(float x[3], float closestPoint[3],
                              int& subId, float pcoords[3], 
                              float& dist2, float *weights)
{
  float *pt1, *pt2, *pt3, *pt4;
  int i;

  subId = 0;
//
// Get coordinate system
//
  pt1 = this->Points.GetPoint(0);
  pt2 = this->Points.GetPoint(1);
  pt3 = this->Points.GetPoint(2);
  pt4 = this->Points.GetPoint(4);
//
// Develop parametric coordinates
//
  pcoords[0] = (x[0] - pt1[0]) / (pt2[0] - pt1[0]);
  pcoords[1] = (x[1] - pt1[1]) / (pt3[1] - pt1[1]);
  pcoords[2] = (x[2] - pt1[2]) / (pt4[2] - pt1[2]);

  if ( pcoords[0] >= 0.0 && pcoords[0] <= 1.0 && // CORRECTED
  pcoords[1] >= 0.0 && pcoords[1] <= 1.0 &&
  pcoords[2] >= 0.0 && pcoords[2] <= 1.0 )
    {
    closestPoint[0] = x[0]; closestPoint[1] = x[1]; closestPoint[2] = x[2];
    dist2 = 0.0; // inside voxel
    this->InterpolationFunctions(pcoords,weights);
    return 1;
    }
  else
    {
    float pc[3], w[8];
    for (i=0; i<3; i++)
      {
      if (pcoords[i] < 0.0) pc[i] = 0.0;
      else if (pcoords[i] > 1.0) pc[i] = 1.0;
      else pc[i] = pcoords[i];
      }
    this->EvaluateLocation(subId, pc, closestPoint, (float *)w);
    dist2 = vtkMath::Distance2BetweenPoints(closestPoint,x);
    return 0;
    }
}



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