diff --git a/apps/nexus/normalscone.cpp b/apps/nexus/normalscone.cpp
new file mode 100644
index 00000000..cd6e95af
--- /dev/null
+++ b/apps/nexus/normalscone.cpp
@@ -0,0 +1,177 @@
+#include "normalscone.h"
+#include <iostream>
+
+using namespace std;
+using namespace vcg;
+using namespace nxs;
+
+
+ANCone3f::ANCone3f() {
+  scaledNormal = Point3f(0,0,0);
+  frontAnchor = Point3f(0,0,0);
+  backAnchor = Point3f(0,0,0);
+}
+
+bool ANCone3f::Frontface(const Point3f &viewPoint) {
+  Point3f d = frontAnchor - viewPoint; //Vector from viewPoint to frontAnchor.
+  float f = - d * scaledNormal;
+  if (f < 0.001 || f * f < d * d)
+    return false;
+  return true;
+}
+
+bool ANCone3f::Backface(const Point3f &viewPoint) {
+  Point3f d = backAnchor - viewPoint; //Vector from viewPoint to frontAnchor.
+  float f = d * scaledNormal;
+  if (f < 0.001 || f * f < d * d)
+    return false;
+  return true;
+}
+
+void ANCone3f::AddNormals(vector<Point3f> &normal, vector<float> &area, float threshold) {
+  assert(normal.size() == area.size());
+  scaledNormal = Point3f(0,0,0);
+  int count = 0;
+  vector<Point3f>::iterator i;
+  for(i = normal.begin(); i != normal.end(); i++) {
+    scaledNormal += *i;
+    count++;
+  }
+  scaledNormal /= count;
+  scaledNormal.Normalize();
+
+  double distr[50];
+  for(int k = 0; k < 50; k++)
+    distr[k] = 0;
+  double tot_area = 0;
+
+  vector<float>::iterator j;
+  for(i = normal.begin(), j = area.begin(); i != normal.end(); i++, j++) {
+    int pos = (int)(49.0 * Angle(scaledNormal, *i)/M_PI);
+    if(pos < 0) continue;
+    assert(pos >=0 && pos < 50);
+    distr[pos] += *j;
+    tot_area += *j;
+  }
+
+  float tot = 0;
+  int best;
+  for(best = 0; best < 50; best++) {
+    tot += distr[best];
+    if(tot > threshold * tot_area)
+      break;
+  }
+  double alpha = M_PI * (best + 1) / 50;
+  if(alpha > M_PI/ 2 - 0.1) 
+    scaledNormal = Point3f(0,0,0);
+  else 
+    scaledNormal /= cos(M_PI/2 - alpha);
+}
+
+void ANCone3f::AddNormals(vector<Point3f> &normal, float threshold) {
+  //assert(normal.size() > 0);
+  scaledNormal = Point3f(0,0,0);
+  int count = 0;
+  vector<Point3f>::iterator i;
+  for(i = normal.begin(); i != normal.end(); i++) {
+    Point3f norm = *i;
+    if(norm.Norm() < 0.00001) continue;
+    norm.Normalize();
+    scaledNormal += norm;
+    count++;
+  }
+  scaledNormal /= count;
+  scaledNormal.Normalize();
+
+  int distr[50];
+  for(int k = 0; k < 50; k++)
+    distr[k] =0;
+
+  for(i = normal.begin(); i != normal.end(); i++) {
+    int pos = (int)(50.0 * Angle(scaledNormal, *i)/M_PI);
+    distr[pos]++;
+  }
+  int tot = 0;
+  int best;
+  //  cerr << "Distr: ";
+  for(best = 0; best < 50; best++) {
+    //    cerr << distr[best] << " ";
+    tot += distr[best];
+    if(tot >= threshold * normal.size())
+      break;
+  }
+  double alpha = M_PI * (best +1) / 50;
+  //  cerr << "best: " << best << " alpha: " << alpha << endl;
+  if(alpha > M_PI/ 2) {
+    scaledNormal = Point3f(0,0,0);
+  } else {
+    scaledNormal /= cos(M_PI/2 - alpha);
+  }
+}
+
+void ANCone3f::AddAnchors(vector<Point3f> &anchors) {
+  assert(anchors.size() > 0);
+  frontAnchor = anchors[0];
+  backAnchor = anchors[0];
+
+  float fa = frontAnchor * scaledNormal;
+  float fb = -backAnchor * scaledNormal;
+
+  vector<Point3f>::iterator i;
+  for(i = anchors.begin(); i != anchors.end(); i++) {
+    Point3f &anchor = *i;
+    float na = anchor * scaledNormal;
+    if(na < fa) {
+      frontAnchor = anchor;
+      fa = na;
+    }
+    if(-na < fb) {
+      backAnchor = anchor;
+      fb = -na;
+    }
+  }
+}
+
+void NCone3s::Import(const ANCone3f &c) {
+  Point3f normal = c.scaledNormal;
+  float len = normal.Norm();
+  if(len != 0) 
+    normal /= len;
+
+  assert(normal[0] <= 1 && normal[1] <= 1 && normal[2] <= 1);
+  assert(normal[0] >= -1 && normal[1] >= -1 && normal[2] >= -1);
+  n[0] = (short)(normal[0] * 32766);
+  n[1] = (short)(normal[1] * 32766);
+  n[2] = (short)(normal[2] * 32766);
+  //i want to rapresent number from 1 to 10
+  if(len > 10.0f) len = 10.0f;
+  if(len < -10.0f) len = -10.0f;
+  n[3] = (short)(len * 3276);
+}
+
+
+
+
+bool NCone3s::Backface(const vcg::Sphere3f &sphere, 
+		       const vcg::Point3f &view) const {
+  vcg::Point3f norm(n[0]/32766.0f, n[1]/32766.0f, n[2]/32766.0f);
+  vcg::Point3f d = (sphere.Center() + norm * sphere.Radius()) - view;
+  norm *= n[3]/3276.0f;
+
+  float f = d * norm;
+  if (f < 0.001 || f * f < d * d) 
+    return false;
+  return true;
+}
+
+bool NCone3s::Frontface(const vcg::Sphere3f &sphere, 
+			const vcg::Point3f &view) const {
+  vcg::Point3f norm(n[0]/32766.0f, n[1]/32766.0f, n[2]/32766.0f);
+  vcg::Point3f d = (sphere.Center() - norm * sphere.Radius()) - view;
+  norm *= n[3]/3276.0f;
+  
+  float f = -d * norm;
+  if (f < 0.001 || f * f < d * d)
+    return false;
+  return true;
+}
diff --git a/apps/nexus/normalscone.h b/apps/nexus/normalscone.h
new file mode 100644
index 00000000..af017531
--- /dev/null
+++ b/apps/nexus/normalscone.h
@@ -0,0 +1,53 @@
+#ifndef NXS_NORMALS_CONE_H
+#define NXS_NORMALS_CONE_H
+
+#include <vector>
+
+#include <vcg/space/point3.h>
+#include <vcg/space/sphere3.h>
+
+namespace nxs {
+
+  
+  //anchored normal cone.
+  class ANCone3f {
+  public:
+    ANCone3f();
+
+    bool Frontface(const vcg::Point3f &viewPoint);
+    bool Backface(const vcg::Point3f &viewPoint);
+
+    //threshold [0, 1]: percentage of normals to left out
+    void AddNormals(std::vector<vcg::Point3f> &normals, 
+		    float threshold = 1.0f);
+    void AddNormals(std::vector<vcg::Point3f> &normals, 
+		    std::vector<float> &areas, 
+		    float threshold = 1.0f);
+    void AddAnchors(std::vector<vcg::Point3f> &anchors);
+  protected:
+    vcg::Point3f scaledNormal;
+    vcg::Point3f frontAnchor;
+    vcg::Point3f backAnchor;
+    
+    friend class NCone3s;
+  };
+
+
+
+  //this is not anchored... need a bounding sphere to report something
+  class NCone3s {
+  public:
+    void Import(const ANCone3f &c);
+    
+    bool Backface(const vcg::Sphere3f &sphere, 
+		  const vcg::Point3f &view) const;
+    bool Frontface(const vcg::Sphere3f &sphere, 
+		   const vcg::Point3f &view) const;    
+
+    //encode normal and sin(alpha) in n[3]
+    short n[4];
+  };
+
+}
+
+#endif