VTK研究ノート（25）vtk空間幾何学的変換（3）

vtkで指定した軸を中心に角度を回転させます

void vtkTransformConcatenation::Rotate(double angle, double x, double y, double z)
{
    
    
  if (angle == 0.0 || (x == 0.0 && y == 0.0 && z == 0.0))
  {
    
    
    return;
  }

  // convert to radians
  angle = vtkMath::RadiansFromDegrees(angle);

  // make a normalized quaternion
  double w = cos(0.5 * angle);
  double f = sin(0.5 * angle) / sqrt(x * x + y * y + z * z);
  x *= f;
  y *= f;
  z *= f;

  // convert the quaternion to a matrix
  double matrix[4][4];
  vtkMatrix4x4::Identity(*matrix);

  double ww = w * w;
  double wx = w * x;
  double wy = w * y;
  double wz = w * z;

  double xx = x * x;
  double yy = y * y;
  double zz = z * z;

  double xy = x * y;
  double xz = x * z;
  double yz = y * z;

  double s = ww - xx - yy - zz;

  matrix[0][0] = xx * 2 + s;
  matrix[1][0] = (xy + wz) * 2;
  matrix[2][0] = (xz - wy) * 2;

  matrix[0][1] = (xy - wz) * 2;
  matrix[1][1] = yy * 2 + s;
  matrix[2][1] = (yz + wx) * 2;

  matrix[0][2] = (xz + wy) * 2;
  matrix[1][2] = (yz - wx) * 2;
  matrix[2][2] = zz * 2 + s;

  this->Concatenate(*matrix);
}