Rendering/vtkCamera.cxx
void vtkCamera::Dolly(double amount)
{
  if (amount <= 0.0)
    {
    return;
    }

// dolly moves the camera towards the focus
  double d = this->Distance/amount;

  this->SetPosition(this->FocalPoint[0] - d*this->DirectionOfProjection[0],
                    this->FocalPoint[1] - d*this->DirectionOfProjection[1],
                    this->FocalPoint[2] - d*this->DirectionOfProjection[2]);
}
//----------------------------------------------------------------------------
// Move the position of the camera along the view plane normal. Moving
// towards the focal point (e.g., > 1) is a dolly-in, moving away
// from the focal point (e.g., < 1) is a dolly-out.
Move the position of the camera along the view plane normal. Moving
towards the focal point  is a dolly-in, moving away
from the focal point  is a dolly-out.
Move the position of the camera along the view plane normal . Moving towards the focal point is a dolly - in moving away from the focal point is a dolly - out .
void vtkCamera::Dolly(double amount)
{
  if (amount <= 0.0)
    {
    return;
    }
  double d = this->Distance/amount;
  this->SetPosition(this->FocalPoint[0] - d*this->DirectionOfProjection[0],
                    this->FocalPoint[1] - d*this->DirectionOfProjection[1],
                    this->FocalPoint[2] - d*this->DirectionOfProjection[2]);
}
void vtkCamera :: Dolly ( double amount ) { if ( amount <= 0.0 ) { return ; } double d = this -> Distance / amount ; this -> SetPosition ( this -> FocalPoint [ 0 ] - d * this -> DirectionOfProjection [ 0 ] , this -> FocalPoint [ 1 ] - d * this -> DirectionOfProjection [ 1 ] , this -> FocalPoint [ 2 ] - d * this -> DirectionOfProjection [ 2 ] ) ; }
Move the position of the camera along the view plane normal.
Move the position of the camera along the view plane normal .
// dolly moves the camera towards the focus