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/*=========================================================================
Program: Visualization Toolkit
Module: vtkCylinder.cxx
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 "vtkCylinder.h"
#include "vtkMath.h"
#include "vtkObjectFactory.h"
vtkStandardNewMacro(vtkCylinder);
//----------------------------------------------------------------------------
// Construct cylinder radius of 0.5.
vtkCylinder::vtkCylinder()
{
this->Center[0] = this->Center[1] = this->Center[2] = 0.0;
this->Axis[0] = 0.0;
this->Axis[1] = 1.0;
this->Axis[2] = 0.0;
this->Radius = 0.5;
}
//----------------------------------------------------------------------------
// Evaluate cylinder equation F(x,y,z) along specified Axis. Note that this is
// basically a distance to line computation, compared to the cylinder radius.
double vtkCylinder::EvaluateFunction(double x[3])
{
// Determine distance^2 of point to axis. Note that cylinder Axis is
// always normalized and always non-zero.
double x2C[3];
x2C[0] = x[0] - this->Center[0];
x2C[1] = x[1] - this->Center[1];
x2C[2] = x[2] - this->Center[2];
// projection onto cylinder axis
double proj = vtkMath::Dot(this->Axis, x2C);
// return distance^2 - R^2
return ((vtkMath::Dot(x2C, x2C) - proj * proj) - this->Radius * this->Radius);
}
//----------------------------------------------------------------------------
// Evaluate cylinder function gradient (along potentially oriented axis). The
// gradient is always in the radial direction, and thus must be projected
// onto the three x-y-z coordinate axes.
void vtkCylinder::EvaluateGradient(double x[3], double g[3])
{
// Determine the radial vector from the point x to the line. This
// means finding the closest point to the line. Get parametric
// location along cylinder axis. Remember Axis is normalized.
double t = this->Axis[0] * (x[0] - this->Center[0]) + this->Axis[1] * (x[1] - this->Center[1]) +
this->Axis[2] * (x[2] - this->Center[2]);
// Compute closest point
double cp[3];
cp[0] = this->Center[0] + t * this->Axis[0];
cp[1] = this->Center[1] + t * this->Axis[1];
cp[2] = this->Center[2] + t * this->Axis[2];
// Gradient is 2*r. Project onto x-y-z axes.
g[0] = 2.0 * (x[0] - cp[0]);
g[1] = 2.0 * (x[1] - cp[1]);
g[2] = 2.0 * (x[2] - cp[2]);
}
//----------------------------------------------------------------------------
// Specify the cylinder axis. Normalize if necessary.
void vtkCylinder::SetAxis(double ax, double ay, double az)
{
double axis[3];
axis[0] = ax;
axis[1] = ay;
axis[2] = az;
this->SetAxis(axis);
}
//----------------------------------------------------------------------------
// Specify the cylinder axis. Reject non-zero axis vectors. It normalizes the
// axis vector.
void vtkCylinder::SetAxis(double a[3])
{
// If axis length is zero, then don't change it
if (vtkMath::Normalize(a) < DBL_EPSILON)
{
return;
}
if (a[0] != this->Axis[0] || a[1] != this->Axis[1] || a[2] != this->Axis[2])
{
this->Modified();
this->Axis[0] = a[0];
this->Axis[1] = a[1];
this->Axis[2] = a[2];
}
}
//----------------------------------------------------------------------------
void vtkCylinder::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os, indent);
os << indent << "Center: "
<< "( " << this->Center[0] << ", " << this->Center[1] << ", " << this->Center[2] << " )";
os << indent << "Axis: "
<< "( " << this->Axis[0] << ", " << this->Axis[1] << ", " << this->Axis[2] << " )";
os << indent << "Radius: " << this->Radius << "\n";
}
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