问题描述
基于此示例(使用曲面将多面域重新网格化)在 3D网格生成手册)中，我想对一个立方体进行网格划分形的域，其中平面受到保护(请参见下面的代码).但是， make_mesh_3 会引发断言冲突:
Based on this example (Remeshing a Polyhedral Domain with Surfaces in the 3D Mesh Generation Manual), I want to mesh a cube-shaped domain with its midplane protected (see the code below). However, make_mesh_3 throws an assertion violation:
CGAL ERROR: assertion violation!
Expr: minimal_size_ > 0 || sq_d > 0
不要轻视示例，这只是为了显示问题.基于这讨论，我认为问题是 detect_features 创建了相互相交的折线(中平面的周长与立方体边缘相交，并且都作为要素添加)
Nevermind the triviality of the example, it's just to show the problem. Based on this discussion, I think the issue is that detect_features creates polylines that intersect each other (perimeter of the midplane intersects the cube edges, and both are added as features).
meshdomain中不允许相交多面体吗?如果是这样，是否有一种方法可以访问和操纵 detect_features 的结果来处理冲突的功能?我试图弄清楚折线是如何存储在网格域中的，但是我却一无所获.
Are intersecting polyhedra not allowed in the meshdomain? If so, is there a way to access and manipulate the results of detect_features to process conflicting features? I'm trying to figure out how polylines are stored in the mesh domain, but I'm getting nowhere.
// --- External Includes ---
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Mesh_polyhedron_3.h>
#include <CGAL/Polyhedral_mesh_domain_with_features_3.h>
#include <CGAL/Mesh_triangulation_3.h>
#include <CGAL/Mesh_complex_3_in_triangulation_3.h>
#include <CGAL/Mesh_criteria_3.h>
#include <CGAL/make_mesh_3.h>
// CGAL types
namespace cgal {
using Kernel = CGAL::Exact_predicates_inexact_constructions_kernel;
using ConcurrencyTag = CGAL::Sequential_tag;
using PolyhedronSurface = CGAL::Mesh_polyhedron_3<Kernel>::type;
using MeshDomain = CGAL::Polyhedral_mesh_domain_with_features_3<Kernel>;
using Tr = CGAL::Mesh_triangulation_3<MeshDomain,CGAL::Default,ConcurrencyTag>::type;
using Triangulation = CGAL::Mesh_complex_3_in_triangulation_3<Tr>;
using MeshCriteria = CGAL::Mesh_criteria_3<Tr>;
using Point = cgal::MeshDomain::Point_3;
}
int main()
{
// Define points for the cube and midPlane
std::vector<cgal::Point> points =
{
cgal::Point( 1.0, 0.0, 0.0),
cgal::Point( 1.0, 1.0, 0.0),
cgal::Point( 0.0, 1.0, 0.0),
cgal::Point( 0.0, 0.0, 0.0),
cgal::Point( 1.0, 0.0, 1.0),
cgal::Point( 1.0, 1.0, 1.0),
cgal::Point( 0.0, 1.0, 1.0),
cgal::Point( 0.0, 0.0, 1.0),
cgal::Point( 1.0, 0.0, 0.5),
cgal::Point( 1.0, 1.0, 0.5),
cgal::Point( 0.0, 1.0, 0.5),
cgal::Point( 0.0, 0.0, 0.5)
};
// Create polyhedra
cgal::PolyhedronSurface cube, midPlane;
cube.make_triangle( points[0], points[3], points[1]);
cube.make_triangle( points[1], points[3], points[2]);
cube.make_triangle( points[4], points[5], points[7]);
cube.make_triangle( points[5], points[6], points[7]);
cube.make_triangle( points[0], points[4], points[3]);
cube.make_triangle( points[3], points[4], points[7]);
cube.make_triangle( points[1], points[2], points[5]);
cube.make_triangle( points[2], points[6], points[5]);
cube.make_triangle( points[2], points[3], points[6]);
cube.make_triangle( points[3], points[7], points[6]);
cube.make_triangle( points[0], points[1], points[5]);
cube.make_triangle( points[0], points[5], points[4]);
midPlane.make_triangle( points[8], points[9], points[10]);
midPlane.make_triangle( points[8], points[10], points[11]);
// Triangulation
cgal::MeshDomain meshDomain( midPlane, cube );
meshDomain.detect_features();
cgal::MeshCriteria meshCriteria( CGAL::parameters::facet_angle = 30,
CGAL::parameters::edge_size = 0.2 );
auto triangulation = CGAL::make_mesh_3<cgal::Triangulation>( meshDomain,
meshCriteria );
return 0;
}
推荐答案
对于您的立方体，应该容易地构造多面体复合体，即三个表面，即立方体的上部和下部以及中间的正方形.看看此示例.
For your cube it should be easy to construct a polyhedral complex, that is three surfaces, namely the upper and lower part of the cube, and the mid-square. Have a look at this example.
这篇关于CGAL detect_features()创建不可保护的功能的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！