Method GetProjectionTransformMatrix

Rendering/Core/vtkCamera.cxx:1153–1179

------------------------------------------------------------------------------ Return the projection transform matrix. See ComputeProjectionTransform.

//------------------------------------------------------------------------------
// Return the projection transform matrix. See ComputeProjectionTransform.
vtkMatrix4x4* vtkCamera::GetProjectionTransformMatrix(vtkRenderer* ren)
{
  double aspect[2];
  int lowerLeft[2];
  int usize, vsize;
  vtkMatrix4x4* matrix = vtkMatrix4x4::New();

  ren->GetTiledSizeAndOrigin(&usize, &vsize, lowerLeft, lowerLeft + 1);

  // some renderer subclasses may have more complicated computations for the
  // aspect ratio. So take that into account by computing the difference
  // between our simple aspect ratio and what the actual renderer is reporting.
  ren->ComputeAspect();
  ren->GetAspect(aspect);
  double aspect2[2];
  ren->vtkViewport::ComputeAspect();
  ren->vtkViewport::GetAspect(aspect2);
  double aspectModification = aspect[0] * aspect2[1] / (aspect[1] * aspect2[0]);

  if (usize && vsize)
  {
    matrix->DeepCopy(this->GetProjectionTransformMatrix(aspectModification * usize / vsize, -1, 1));
    matrix->Transpose();
  }

  return matrix;
}

//------------------------------------------------------------------------------
// Return the projection transform matrix. See ComputeProjectionTransform.