C++ ON_3dVector::Reverse方法代码示例

bool ON_PolyEdgeCurve::EvSrfTangent( 
        double t,
        bool bIsoDir,
        ON_3dPoint& srfpoint,
        ON_3dVector& srftangent,
        ON_3dVector& srfnormal
        ) const
{
  ON_3dPoint srfpt;
  ON_3dVector du, dv, duu, duv, dvv;
  bool rc = EvSrfDerivatives(t,srfpoint,du,dv,duu,duv,dvv);
  if (rc )
    rc = ON_EvNormal( 0, du, dv, duu, duv, dvv, srfnormal ) ? true : false;
  if (rc)
  {
    int segment_index = SegmentIndex(t);
    ON_PolyEdgeSegment* seg = SegmentCurve(segment_index);
    if ( seg )
    {
      if ( bIsoDir && seg->IsoType() == ON_Surface::not_iso )
        bIsoDir = false;
      
      ON_3dVector crvtangent = TangentAt(t);
      ON_3dVector binormal = ON_CrossProduct(crvtangent,srfnormal);
      binormal.Unitize();
      if ( seg->ReversedTrimDir() )
        binormal.Reverse();
      // at this point, binormal points "out" and is tangent
      // to the surface.
      if ( bIsoDir )
      {
        du.Unitize();
        dv.Unitize();
        double B_dot_du = binormal*du;
        double B_dot_dv = binormal*dv;
        if ( fabs(B_dot_dv) > fabs(B_dot_du) )
        {
          if (B_dot_dv < 0.0)
            dv.Reverse();
          srftangent = dv;
        }
        else
        {
          if (B_dot_du < 0.0)
            du.Reverse();
          srftangent = du;
        }
      }
      else
        srftangent = binormal;

      if ( seg && seg->m_face && seg->m_face->m_bRev )
        srfnormal.Reverse();
    }
    else
      rc = false;
  }
  return rc;
}

ON_3dVector ON_Light::PerpindicularDirection() const
{
  // returns a consistent vector perpendicular to the
  // light's direction.  This vector is useful for
  // user interface display.
  ON_3dVector dir = m_direction;
  if ( !dir.IsValid() || !dir.Unitize() )
    return ON_UNSET_VECTOR;

  ON_3dVector xdir;
  if ( IsLinearLight() || IsRectangularLight() )
  {
    xdir = m_length;
    if ( xdir.IsValid() && xdir.Unitize() && fabs(xdir*dir) <= ON_SQRT_EPSILON )
      return xdir;
  }

  if( dir.IsParallelTo( ON_zaxis, ON_DEGREES_TO_RADIANS * 3.0))
    xdir = ON_CrossProduct( dir, ON_xaxis);
  else
    xdir = ON_CrossProduct( dir, ON_zaxis);
  xdir.Unitize();
  ON_3dVector ydir = ON_CrossProduct(dir,xdir);
  ydir.Unitize();
  ON_3dVector right;

  switch(dir.MaximumCoordinateIndex())
  {
  case 0:
    right = (fabs(xdir.y) > fabs(ydir.y)) ? xdir : ydir;
    if ( right.y < 0.0 )
      right.Reverse();
    break;
  case 1:
  case 2:
    right = (fabs(xdir.x) > fabs(ydir.x)) ? xdir : ydir;
    if ( right.x < 0.0 )
      right.Reverse();
    break;
  default:
    right = xdir;
    break;
  }

  if ( right[right.MaximumCoordinateIndex()] < 0.0 )
    right.Reverse();

  return right;  
}

ON_BOOL32 ON_ArcCurve::SetStartPoint(ON_3dPoint start_point)
{
  if (IsCircle())
    return false;
  ON_BOOL32 rc = false;
  if ( m_dim == 3 || start_point.z == 0.0 )
  {
    ON_3dPoint P;
    ON_3dVector T;
    double t = Domain()[1];
    Ev1Der( t, P, T );
    T.Reverse();
    ON_Arc a;
    rc = a.Create( P, T, start_point );
    if ( rc )
    {
      a.Reverse();
      m_arc = a;
    }
    else {
      ON_3dPoint end_point = PointAt(Domain()[1]);
      if (end_point.DistanceTo(start_point) < ON_ZERO_TOLERANCE*m_arc.Radius()){
        //make arc into circle
        m_arc.plane.xaxis = end_point - m_arc.Center();
        m_arc.plane.xaxis.Unitize();
        m_arc.plane.yaxis = ON_CrossProduct(m_arc.Normal(), m_arc.plane.xaxis);
        m_arc.plane.yaxis.Unitize();
        m_arc.SetAngleRadians(2.0*ON_PI);
        rc = true;
      }
    }
  }
  return rc;  
}