*** empty log message ***

Mesh/BDS.cpp

@@ -213,6 +213,11 @@ void  BDS_Mesh :: del_edge  (BDS_Edge *e)
     e->deleted = true;
     edges_to_delete.insert (e);
 }
+void  BDS_Mesh :: del_point  (BDS_Point *p)
+{
+    points.erase ( p );
+    delete p;
+}
 void BDS_Mesh :: add_geom  (int p1, int p2)
 {
     geom.insert ( new BDS_GeomEntity ( p1,p2 ) ) ;        
@@ -1039,25 +1044,89 @@ bool BDS_Mesh ::swap_edge ( BDS_Edge *e)
     triangles.push_back(t2); 
     return true;
 }
-bool BDS_Mesh ::collapse_edge ( BDS_Edge *e, BDS_Point *p)
+bool BDS_Mesh ::collapse_edge ( BDS_Edge *e, BDS_Point *p, const double eps)
 {
     std::list<BDS_Triangle *> t;
+    BDS_Point *o = e->othervertex (p);
+    X = p->X;
+    Y = p->Y;
+    Z = p->Z;
     p->getTriangles (t); 	
     {
 	std::list<BDS_Triangle *>::iterator it = t.begin();
 	std::list<BDS_Triangle *>::iterator ite = t.end();
 	std::list<BDS_Edge *> cavity;
+	BDS_Triangle * todelete[2];
+	BDS_Edge     * tocollapse[2][2];
+	int nb_del = 0;
 	while ( it != ite )
 	{
 	    BDS_Triangle *t = *it;
-	    if ( t->e1->p1 != p && t->e1->p1 != p) cavity.push_back (t->e1);
-	    else if ( t->e2->p1 != p && t->e2->p1 != p) cavity.push_back (t->e2);
-	    else if ( t->e3->p1 != p && t->e3->p1 != p) cavity.push_back (t->e3);
+	    if (t->e1 != e && t->e2 != e && t->e3 != e)
+	      {
+		double n1[3],n2[3];
+		BDS_Point *pts[3];
+		t->getNodes (pts); 
+		p->X = o->X;
+		p->Y = o->Y;
+		p->Z = o->Z;
+		normal_triangle (pts[0],pts[1],pts[2], n1); // normal after collapse
+		p->X = X;
+		p->Y = Y;
+		p->Z = Z;
+		normal_triangle (pts[0],pts[1],pts[2], n2); // normal before collapse
+		// normals should not be opposed or change too dramatically
+		// this does not concern the triangles with the small edge that
+		// are collapsed too
+		double ps = n1[0] * n2[0] + n1[1] * n2[1] + n1[2] * n2[2];
+		if ( ps < eps ) return false;
+	      }
+	    else
+	      {
+		// this triangle disappears
+		if (nb_del == 2) throw;
+		if (t->e1 == e)
+		  {
+		    tocollapse[nb_del][0] = t->e2;
+		    tocollapse[nb_del][1] = t->e3;
+		  }
+		if (t->e2 == e)
+		  {
+		    tocollapse[nb_del][0] = t->e1;
+		    tocollapse[nb_del][1] = t->e3;
+		  }
+		if (t->e3 == e)
+		  {
+		    tocollapse[nb_del][0] = t->e1;
+		    tocollapse[nb_del][1] = t->e2;
+		  }
 		else throw;
-	    ++it;
+		todelete[nb_del++] = t;
 	      }
+	    ++it;
 	}
+	if (nb_del != 2) throw;
+	// we can collapse
+	// delete the 2 triangles
+	del_triangle ( todelete [0] );
+	del_triangle ( todelete [1] );
+	// delete the edge
+	del_edge (e);
+	// reconnect together faces on  
+	for (int k=0;k<tocollapse[0][0]->numfaces();k++)
+	  tocollapse[0][1]->faces(k)->replaceedge ( tocollapse[0][1], tocollapse[0][0] ); 
+	for (int k=0;k<tocollapse[1][0]->numfaces();k++)
+	  tocollapse[1][1]->faces(k)->replaceedge ( tocollapse[1][1], tocollapse[1][0] ); 
+
+	
 	
+	del_edge (tocollase[0][1]);
+	del_edge (tocollase[1][1]);
+	// delete the point
+	del_point (p);
+       
+    }
+    return true;
 }
 
 bool BDS_Mesh ::smooth_point ( BDS_Point *p)

Mesh/BDS.h

@@ -142,6 +142,13 @@ public:
 	return 0;
       }
 
+    inline BDS_Point * othervertex ( const BDS_Point *p ) const
+      {
+	if (p1 == p) return p2;
+	if (p2 == p) return p1;
+	return 0;
+      }
+
     inline void addface ( BDS_Triangle *f)
 	{
 	    _faces.push_back(f);
@@ -193,6 +200,7 @@ public:
     BDS_Edge *e1,*e2,*e3;
     BDS_Vector N() const ;
     BDS_GeomEntity *g;
+
     inline void getNodes (BDS_Point *n[3]) const
 	{
 	  n[0] = e1->commonvertex (e3);
@@ -206,6 +214,16 @@ public:
 	    e2->addface(this);
 	    e3->addface(this);
 	}
+    void replacedge ( BDS_Edge *a, BDS_Edge *b )
+      {
+	if ( a == e1 )
+	  {
+	    e1->del (this);
+	    e1 = a;
+	    e1->add (this);
+	  }
+      }
+
 };
 class GeomLessThan
 {
@@ -261,6 +279,7 @@ class BDS_Mesh
     std::list<BDS_Triangle*>   triangles; 
     BDS_Point * add_point (int num , double x, double y,double z);
     BDS_Edge  * add_edge  (int p1, int p2);
+    void del_point  (BDS_Point *p);
     void del_edge  (BDS_Edge *e);
     BDS_Triangle *add_triangle  (int p1, int p2, int p3);
     void del_triangle  (BDS_Triangle *t);