OpenCasCade(OCC) 曲面误差求解中的问题汇总

1、显示所有的点云数据
#include <AIS_PointCloud.hxx>包能够找到想要的内容

2、获取某一选中曲面的法向量

    BRepClass3d_SolidExplorer aBSE(t_Shape);//t_shape是选中的TopoDS_Shape
	TopoDS_Face aTFace = TopoDS::Face(t_Shape);
	//Handle(Geom_Surface) aSurface = BRep_Tool::Surface(aTFace);
	BRepAdaptor_Surface aBSurf(aTFace,Standard_True);
	Standard_Real U = 0.0,V = 0.0;
	BRepLProp_SLProps theProp(aBSurf,1,Precision::Confusion());
	theProp.SetParameters(U,V);//初始化U,V两个参数
	gp_Vec theNormal;//曲面法向量
	if (theProp.IsNormalDefined())
	{
		 theNormal = theProp.Normal();
	}

3、计算点云到选中曲面的距离的大小

//方法1 采用 GeomAPI_ProjectPointOnSurf
		//获取最小距离的大小和交点
		TopoDS_Face aTFace = TopoDS::Face(t_Shape);//选中的TopoDS_Shape
	    Handle(Geom_Surface) aSurface = BRep_Tool::Surface(aTFace);
		gp_Pnt p(1,1,1);//将要计算的点
		GeomAPI_ProjectPointOnSurf aGeomPp(p,aSurface,Extrema_ExtAlgo_Grad);
		Standard_Real minDistance = 0.0;//定义最短的距离
		Standard_Real PSdistance = 0.0;
		Standard_Integer minPIndex = 0;//定义最短距离的点的index
		if (aGeomPp.IsDone() && aGeomPp.NbPoints()>0)
		{
			minDistance = aGeomPp.Distance(1);
			minPIndex = 1;
			for(Standard_Integer i = 2; i <= aGeomPp.NbPoints();i++)
			{
				PSdistance = aGeomPp.Distance(i);
				if (minDistance > PSdistance)
				{
					minDistance = PSdistance;
					minPIndex = i;
				}
			}
			gp_Pnt  interPnt = aGeomPp.Point(minPIndex);//与平面最短的那个距离的交点
			gp_Vec PntToPnt(p,interPnt);//定义交点和p的向量
			Standard_Real aReal = aGeomPp.LowerDistance();//自带的函数计算最短距离
			//来判断交点在所选曲面的正向还是反向
			//获取曲面的U,V参数
			aGeomPp.LowerDistanceParameters(U,V);
			aGeomPp.Parameters(minPIndex,U,V);
			gp_Pnt pnt;
			gp_Vec D1U,D1V;
			//计算交点对应的U,V的一阶微分
			GeomLProp_SurfaceTool::D1(aSurface,U,V,pnt,D1U,D1V);
			//计算交点的法向量 =  U,V一阶微分的叉乘
			gp_Vec PntNormal = D1U.Crossed(D1V);
			PntNormal.Normalize();
			Standard_Real pangle =  PntNormal.Angle(PntToPnt);
            //判断是否同向，区分正负值
			if (pangle > PI/2 && pangle <= PI)
			{
				Standard_Real d = -minDistance;
				minDistance = d;
			}
			testdata.push_back(minDistance);
        }

//方法2  采用 Extrema_ExtPS
        BRepClass3d_SolidExplorer aBSE(t_Shape);
	  	TopoDS_Face aTFace = TopoDS::Face(t_Shape);
		Handle(Geom_Surface) aSurface = BRep_Tool::Surface(aTFace);
		BRepAdaptor_Surface aBSurf(aTFace,Standard_True);
		Extrema_ExtPS aEEps(p,aBSurf,1e-6,1e-6,Extrema_ExtFlag_MINMAX,Extrema_ExtAlgo_Grad);
		if (aEEps.IsDone()&&aEEps.NbExt()>0)
		{
			minDistance = sqrt(aEEps.SquareDistance(1));
			minPIndex = 1;
			for(Standard_Integer i = 2;i<=aEEps.NbExt();i++)
			{
				PSdistance = sqrt(aEEps.SquareDistance(i));
				if (minDistance > PSdistance)
				{
					minDistance = PSdistance;
					minPIndex = i;
				}
			}
	    }

4、判断一个点是否在选中的面上

        //采用两种方法显示
		BRepClass3d_SClassifier aBSC(aBSE,p,Precision::PConfusion());
		BRepClass3d_SolidClassifier aBSCF(t_Shape,p,Precision::PConfusion());
		TopAbs_Orientation aTopOri= t_Shape.Orientation();
		TopAbs_State mstate = aBSCF.State();
		TopAbs_State astate = aBSC.State();