Method Ortho

Common/Transforms/vtkPerspectiveTransform.cxx:250–265

------------------------------------------------------------------------------ The orthographic perspective maps [xmin,xmax], [ymin,ymax], [-znear,-zfar] to [-1,+1], [-1,+1], [-1,+1]. From the OpenGL Programmer's guide, 2nd Ed.

// to [-1,+1], [-1,+1], [-1,+1].
// From the OpenGL Programmer's guide, 2nd Ed.
void vtkPerspectiveTransform::Ortho(
  double xmin, double xmax, double ymin, double ymax, double znear, double zfar)
{
  double matrix[4][4];
  vtkMatrix4x4::Identity(*matrix);

  matrix[0][0] = 2 / (xmax - xmin);
  matrix[1][1] = 2 / (ymax - ymin);
  matrix[2][2] = -2 / (zfar - znear);

  matrix[0][3] = -(xmin + xmax) / (xmax - xmin);
  matrix[1][3] = -(ymin + ymax) / (ymax - ymin);
  matrix[2][3] = -(znear + zfar) / (zfar - znear);

  this->Concatenate(*matrix);
}

//------------------------------------------------------------------------------
// The frustum perspective maps a frustum with the front plane at -znear