intersect_other compute intersections between two meshes

Former-commit-id: dd12b9a9114b3637a3326a2673a4fe0bce89b881

include/igl/cgal/intersect_other.cpp

@@ -0,0 +1,123 @@
+#include "intersect.h"
+#include "CGAL_includes.hpp"
+#include "mesh_to_cgal_triangle_list.h"
+
+#ifndef IGL_FIRST_HIT_EXCEPTION
+#define IGL_FIRST_HIT_EXCEPTION 10
+#endif
+
+IGL_INLINE void igl::intersect(
+  const Eigen::MatrixXd & V,
+  const Eigen::MatrixXi & F,
+  const Eigen::MatrixXd & U,
+  const Eigen::MatrixXi & G,
+  const bool first_only,
+  Eigen::MatrixXi & IF)
+{
+  using namespace std;
+  using namespace Eigen;
+
+
+  typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
+  // 3D Primitives
+  typedef CGAL::Point_3<Kernel>    Point_3;
+  typedef CGAL::Segment_3<Kernel>  Segment_3; 
+  typedef CGAL::Triangle_3<Kernel> Triangle_3; 
+  typedef CGAL::Plane_3<Kernel>    Plane_3;
+  typedef CGAL::Tetrahedron_3<Kernel> Tetrahedron_3; 
+  typedef CGAL::Polyhedron_3<Kernel> Polyhedron_3; 
+  typedef CGAL::Nef_polyhedron_3<Kernel> Nef_polyhedron_3; 
+  // 2D Primitives
+  typedef CGAL::Point_2<Kernel>    Point_2;
+  typedef CGAL::Segment_2<Kernel>  Segment_2; 
+  typedef CGAL::Triangle_2<Kernel> Triangle_2; 
+  // 2D Constrained Delaunay Triangulation types
+  typedef CGAL::Triangulation_vertex_base_2<Kernel>  TVB_2;
+  typedef CGAL::Constrained_triangulation_face_base_2<Kernel> CTFB_2;
+  typedef CGAL::Triangulation_data_structure_2<TVB_2,CTFB_2> TDS_2;
+  typedef CGAL::Exact_intersections_tag Itag;
+  typedef CGAL::Constrained_Delaunay_triangulation_2<Kernel,TDS_2,Itag> 
+    CDT_2;
+  typedef CGAL::Constrained_triangulation_plus_2<CDT_2> CDT_plus_2;
+  // Axis-align boxes for all-pairs self-intersection detection
+  typedef std::vector<Triangle_3> Triangles;
+  typedef typename Triangles::iterator TrianglesIterator;
+  typedef typename Triangles::const_iterator TrianglesConstIterator;
+  typedef 
+    CGAL::Box_intersection_d::Box_with_handle_d<double,3,TrianglesIterator> 
+    Box;
+
+  Triangles TF,TG;
+  // Compute and process self intersections
+  mesh_to_cgal_triangle_list(V,F,TF);
+  mesh_to_cgal_triangle_list(U,G,TG);
+  // http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Box_intersection_d/Chapter_main.html#Section_63.5 
+  // Create the corresponding vector of bounding boxes
+  std::vector<Box> F_boxes,G_boxes;
+  const auto box_up = [](Triangles & T, std::vector<Box> & boxes)
+  {
+    boxes.reserve(T.size());
+    for ( 
+      TrianglesIterator tit = T.begin(); 
+      tit != T.end(); 
+      ++tit)
+    {
+      boxes.push_back(Box(tit->bbox(), tit));
+    }
+  };
+  box_up(TF,F_boxes);
+  box_up(TG,G_boxes);
+  std::list<int> lIF;
+  const auto cb = [&](const Box &a, const Box &b)
+  {
+    using namespace std;
+    // index in F and T
+    int fa = a.handle()-TF.begin();
+    int fb = b.handle()-TG.begin();
+    const Triangle_3 & A = *a.handle();
+    const Triangle_3 & B = *b.handle();
+    if(CGAL::do_intersect(A,B))
+    {
+      // There was an intersection
+      lIF.push_back(fa);
+      lIF.push_back(fb);
+      if(first_only)
+      {
+        throw IGL_FIRST_HIT_EXCEPTION;
+      }
+    }
+  };
+  try{
+    CGAL::box_intersection_d(
+      F_boxes.begin(), F_boxes.end(),
+      G_boxes.begin(), G_boxes.end(),
+      cb);
+  }catch(int e)
+  {
+    // Rethrow if not FIRST_HIT_EXCEPTION
+    if(e != IGL_FIRST_HIT_EXCEPTION)
+    {
+      throw e;
+    }
+    // Otherwise just fall through
+  }
+
+  // Convert lIF to Eigen matrix
+  assert(lIF.size()%2 == 0);
+  IF.resize(lIF.size()/2,2);
+  {
+    int i=0;
+    for(
+      list<int>::const_iterator ifit = lIF.begin();
+      ifit!=lIF.end();
+      )
+    {
+      IF(i,0) = (*ifit);
+      ifit++; 
+      IF(i,1) = (*ifit);
+      ifit++;
+      i++;
+    }
+  }
+
+}

include/igl/cgal/intersect_other.h

@@ -0,0 +1,30 @@
+#ifndef IGL_INTERSECT_H
+#define IGL_INTERSECT_H
+#include <igl/igl_inline.h>
+
+#include <Eigen/Dense>
+
+#ifdef MEX
+#  include <mex.h>
+#  include <cassert>
+#  undef assert
+#  define assert( isOK ) ( (isOK) ? (void)0 : (void) mexErrMsgTxt(C_STR(__FILE__<<":"<<__LINE__<<": failed assertion `"<<#isOK<<"'"<<std::endl) ) )
+#endif
+
+namespace igl
+{
+  IGL_INLINE void intersect(
+    const Eigen::MatrixXd & V,
+    const Eigen::MatrixXi & F,
+    const Eigen::MatrixXd & U,
+    const Eigen::MatrixXi & G,
+    const bool first_only,
+    Eigen::MatrixXi & IF);
+}
+
+#ifdef IGL_HEADER_ONLY
+#  include "intersect.cpp"
+#endif
+  
+#endif
+