OpenCasCade数学库 - 包围盒（Bnd_Box）的变换(Transformed)

1.包围盒（Bnd_Box）的定义

class Bnd_Box
{
public:
    ...
private:
  Standard_Real Xmin;
  Standard_Real Xmax;
  Standard_Real Ymin;
  Standard_Real Ymax;
  Standard_Real Zmin;
  Standard_Real Zmax;
  Standard_Real Gap;
  Standard_Integer Flags;
};

2.变换(gp_Trsf)的定义

class gp_Trsf
{
public:
    ...
private:
  Standard_Real scale;
  gp_TrsfForm shape;     //几何变换类型
  gp_Mat matrix;
  gp_XYZ loc;
};

3.包围盒的变换(Transformed)

Bnd_Box Bnd_Box::Transformed (const gp_Trsf& T) const
{
  gp_TrsfForm F = T.Form();
  Bnd_Box newb(*this);
  if ( IsVoid() ) return newb;

  if      (F == gp_Identity) {}               //没有变化
  else if (F == gp_Translation) {             //平移
    Standard_Real DX,DY,DZ;
    (T.TranslationPart()).Coord(DX,DY,DZ);
    if (!IsOpenXmin()) newb.Xmin += DX;
    if (!IsOpenXmax()) newb.Xmax += DX;
    if (!IsOpenYmin()) newb.Ymin += DY;
    if (!IsOpenYmax()) newb.Ymax += DY;
    if (!IsOpenZmin()) newb.Zmin += DZ;
    if (!IsOpenZmax()) newb.Zmax += DZ;
  }
  else {
    gp_Pnt P[8];
    Standard_Boolean Vertex[8];
    Standard_Integer i;
    for (i=0;i<8;i++) Vertex[i] = Standard_True;
    gp_Dir D[6];
//    Standard_Integer vertices = 0;
    Standard_Integer directions = 0;

    if (IsOpenXmin())
    {
      directions++;
      D[directions-1].SetCoord(-1., 0., 0.);
      Vertex[0] = Vertex[2] = Vertex[4] = Vertex[6] = Standard_False;
    }
    if (IsOpenXmax())
    {
      directions++;
      D[directions-1].SetCoord( 1., 0., 0.);
      Vertex[1] = Vertex[3] = Vertex[5] = Vertex[7] = Standard_False;
    }
    if (IsOpenYmin())
    {
      directions++;
      D[directions-1].SetCoord( 0.,-1., 0.);
      Vertex[0] = Vertex[1] = Vertex[4] = Vertex[5] = Standard_False;
    }
    if (IsOpenYmax())
    {
      directions++;
      D[directions-1].SetCoord( 0., 1., 0.);
      Vertex[2] = Vertex[3] = Vertex[6] = Vertex[7] = Standard_False;
    }
    if (IsOpenZmin())
    {
      directions++;
      D[directions-1].SetCoord( 0., 0.,-1.);
      Vertex[0] = Vertex[1] = Vertex[2] = Vertex[3] = Standard_False;
    }
    if (IsOpenZmax())
    {
      directions++;
      D[directions-1].SetCoord( 0., 0., 1.);
      Vertex[4] = Vertex[5] = Vertex[6] = Vertex[7] = Standard_False;
    }

    newb.SetVoid();
    for (i=0;i<directions;i++) {    //只对开放区间的方向做转换
      D[i].Transform(T);
      newb.Add(D[i]);
    }
    P[0].SetCoord(Xmin,Ymin,Zmin);
    P[1].SetCoord(Xmax,Ymin,Zmin);
    P[2].SetCoord(Xmin,Ymax,Zmin);
    P[3].SetCoord(Xmax,Ymax,Zmin);
    P[4].SetCoord(Xmin,Ymin,Zmax);
    P[5].SetCoord(Xmax,Ymin,Zmax);
    P[6].SetCoord(Xmin,Ymax,Zmax);
    P[7].SetCoord(Xmax,Ymax,Zmax);
    for (i=0;i<8;i++) {
      if (Vertex[i]) {       //只对封闭区间的点做转换
	    P[i].Transform(T);
	    newb.Add(P[i]);
      }
    }
    newb.Gap=Gap;
  }
  return newb;
}