OCC笔记：BRepMesh_IncrementalMesh的使用

1. 函数接口

2. 线性偏转与角度偏转

2.1. theLineDeflection：线性偏转

根据文档推导下

isRelative传入Standard_True时，theLineDeflection为相对值。
参看isRelative说明

//! @param isRelative if TRUE deflection used for discretization of
//! each edge will be * . Deflection
//! used for the faces will be the maximum deflection of their edges.

a对应圆心角，与推导的不一致，推导出来的a若是15度，则圆心角应该是30度，对应12条边。实际却大于12条，大概18条。occ提供的这个参数有点没搞懂，暂时就这样搁置这个问题吧。

2.2. theAngleDeflection： 角度偏转

Standard_Real angDeflection = TMP_PI * 60 / 180; //theta的一半为拆分边对应的圆心角，
假如对一圆面进行拆分
TMP_PI * 60 / 180; //表示是30度的圆心角，边数为360/30 = 12
TMP_PI * 120 / 180; //表示是60度的圆心角，边数为360/60 = 6

按文档推导下：

3.访问网格化信息
You can obtain information on the shape by first exploring it. To access triangulation of a face in the shape later, use BRepTool::Triangulation. To access a polygon, which is the approximation of an edge of the face, use BRepTool::PolygonOnTriangulation.