diff --git a/wrap/gui/trackball.cpp b/wrap/gui/trackball.cpp
index 977dd375..a7a87c62 100644
--- a/wrap/gui/trackball.cpp
+++ b/wrap/gui/trackball.cpp
@@ -24,6 +24,9 @@
   History
 
 $Log: not supported by cvs2svn $
+Revision 1.25  2008/02/22 18:57:46  benedetti
+first attempt to correct after quaternion ToMatrix() inversion (does not work yet)
+
 Revision 1.24  2007/12/21 12:29:34  tarini
 *** empty log message ***
 
@@ -195,9 +198,10 @@ void Trackball::Scale(const float s)
 
 void Trackball::Translate(Point3f tr)
 {
-  Matrix44f m;  
-  track.rot.ToMatrix(m); 
-  track.tra = last_track.tra + m*tr/track.sca;
+//  Matrix44f m;  
+//  track.rot.ToMatrix(m); 
+//  track.tra = last_track.tra + m*tr/track.sca;
+    track.tra = last_track.tra + tr;
 }
 
 /***************************************************************/
diff --git a/wrap/gui/trackmode.cpp b/wrap/gui/trackmode.cpp
index ccab6001..9db16f4e 100644
--- a/wrap/gui/trackmode.cpp
+++ b/wrap/gui/trackmode.cpp
@@ -24,6 +24,9 @@
   History
 
 $Log: not supported by cvs2svn $
+Revision 1.26  2008/02/15 20:56:41  benedetti
+removed some variable initialization related warning, added snap to CylinderMode
+
 Revision 1.25  2007/10/24 10:39:07  ponchio
 #include <gl/glew.h> -> #include <GL/glew.h>
 
@@ -167,11 +170,12 @@ void SphereMode::Apply (Trackball * tb, Point3f new_point)
   Point3f hitOld = HitSphere (tb, tb->last_point);
   Point3f hitNew = HitSphere (tb, new_point);
   tb->Hits.push_back (hitNew);
-  Point3f center = tb->center;
+  Point3f center = tb->center + tb->track.tra;
   Point3f axis = (hitNew - center) ^ (hitOld - center);
   //  Figure out how much to rotate around that axis.
   float phi = Distance (hitNew, hitOld) / tb->radius;
-  tb->track.rot = tb->last_track.rot * Quaternionf (phi, axis);
+//  tb->track.rot = tb->last_track.rot * Quaternionf (-phi, axis);
+  tb->track.rot = Quaternionf (-phi, axis) * tb->last_track.rot;
 }
 
 void SphereMode::Draw(Trackball * tb){
diff --git a/wrap/gui/trackutils.h b/wrap/gui/trackutils.h
index be170575..176de92b 100644
--- a/wrap/gui/trackutils.h
+++ b/wrap/gui/trackutils.h
@@ -24,6 +24,9 @@
   History
 
 $Log: not supported by cvs2svn $
+Revision 1.9  2008/02/22 18:57:47  benedetti
+first attempt to correct after quaternion ToMatrix() inversion (does not work yet)
+
 Revision 1.8  2008/02/15 20:54:45  benedetti
 removed some variable initialization related warning
 
@@ -62,6 +65,8 @@ Utility functions for the trackmodes, first version
 #include <wrap/gl/math.h>
 #include <wrap/gl/space.h>
 #include <vector>
+#include <iostream>
+using namespace std;
 
 namespace vcg {
 
@@ -216,17 +221,20 @@ eq cono                y=x+sqrt(2);
 */
 Point3f HitSphere (Trackball * tb, const Point3f & p)
 {
-  // const float Thr = tb->radius/math::Sqrt(2.0f);
-  Line3fN vn = tb->camera.ViewLineFromModel (tb->center);
-  Line3fN ln = tb->camera.ViewLineFromWindow (Point3f (p[0], p[1], 0));
-  Point3f viewpoint = tb->camera.ViewPoint ();
-  Plane3f vp = GetViewPlane (tb->camera, tb->center);
-  Point3f hit(0,0,0), hitPlane(0,0,0), hitSphere(0,0,0), hitSphere1(0,0,0), hitSphere2(0,0,0), hitHyper(0,0,0);
+  Point3f center = tb->center + tb->track.tra;
+  Line3fN ln = tb->camera.ViewLineFromWindow (Point3f (p[0], p[1], 0));  
+  Plane3f vp = GetViewPlane (tb->camera, center);
+  Point3f hitPlane(0,0,0), //intersection view plane with point touched
+          hitSphere(0,0,0), 
+          hitSphere1(0,0,0), 
+          hitSphere2(0,0,0), 
+          hitHyper(0,0,0);
   IntersectionLinePlane < float >(vp, ln, hitPlane);
-
-  Sphere3f sphere (tb->center, tb->radius);
+  
+  Sphere3f sphere (center, tb->radius);//trackball sphere
   bool resSp = IntersectionLineSphere < float >(sphere, ln, hitSphere1, hitSphere2);
 
+  Point3f viewpoint = tb->camera.ViewPoint ();
   if (resSp == true) {
     if (Distance (viewpoint, hitSphere1) < Distance (viewpoint, hitSphere2))
       hitSphere = hitSphere1;
@@ -234,14 +242,14 @@ Point3f HitSphere (Trackball * tb, const Point3f & p)
       hitSphere = hitSphere2;
   }
 
-  /*float dl= */ Distance (ln, tb->center);
-  bool resHp = HitHyper (tb->center, tb->radius, viewpoint, vp, hitPlane, hitHyper);
+  /*float dl= */ Distance (ln, center);
+  bool resHp = HitHyper (center, tb->radius, viewpoint, vp, hitPlane, hitHyper);
 
   // four cases
 
   // 1) Degenerate line tangent to both sphere and hyperboloid!
   if ((!resSp && !resHp)) {
-    hit = ClosestPoint (ln, tb->center);
+    Point3f hit = ClosestPoint (ln, center);
     //printf("closest point to line %f\n",Distance(hit,tb->center));
     return hit;
   }
@@ -251,7 +259,7 @@ Point3f HitSphere (Trackball * tb, const Point3f & p)
     return hitHyper;            // 3) line cross only the hyperboloid
 
   // 4) line cross both sphere and hyperboloid: choose according angle.
-  float angleDeg = math::ToDeg (Angle ((viewpoint - tb->center), (hitSphere - tb->center)));
+  float angleDeg = math::ToDeg (Angle ((viewpoint - center), (hitSphere - center)));
 
   //printf("Angle %f (%5.2f %5.2f %5.2f) (%5.2f %5.2f %5.2f)\n",angleDeg,hitSphere[0],hitSphere[1],hitSphere[2],hitHyper[0],hitHyper[1],hitHyper[2]);
   if (angleDeg < 45)
@@ -667,12 +675,7 @@ void DrawSphereIcon (Trackball * tb,bool active)
   glMatrixMode(GL_MODELVIEW);
 	glPushMatrix ();
   glTranslate (tb->center);
-  glMultMatrix (tb->track.InverseMatrix ());
   glScale (tb->radius);
-  Matrix44f r;
-  tb->track.rot.ToMatrix (r);
-
-  glMultMatrix (Inverse(r));
   
 	float amb[4] = { .3f, .3f, .3f, 1.0f };
   float col[4] = { .5f, .5f, .8f, 1.0f };