diff --git a/Engine.cc b/Engine.cc
index fbeabd9..33c0119 100644
--- a/Engine.cc
+++ b/Engine.cc
@@ -283,6 +283,7 @@ int Engine::addObject(WFObj * obj, bool is_static, bool is_reference,
 {
     int id = m_next_object_index++;
     Object * o = new Object(is_static, is_reference, m_world, obj, scale);
+    o->setID(id);
     m_objects[id] = o;
     return id;
 }
@@ -292,6 +293,7 @@ int Engine::addObject(bool is_static, bool is_reference,
 {
     int id = m_next_object_index++;
     Object * o = new Object(is_static, is_reference, m_world, geom_type, args);
+    o->setID(id);
     m_objects[id] = o;
     return id;
 }
@@ -407,6 +409,7 @@ int Engine::cloneObject(const Engine::Object * obj)
 {
     int id = m_next_object_index++;
     Object * o = new Object(*obj);
+    o->setID(id);
     m_objects[id] = o;
     return id;
 }
@@ -660,7 +663,13 @@ refptr< vector<int> > Engine::pickObjects(int x, int y)
             rotated_direction[0], rotated_direction[1], rotated_direction[2]);
 
     refptr< vector<int> > ret = new vector<int>();
-    /* TODO: finish */
+    for (vector<OdeWorld::Object *>::const_iterator it = objects->begin();
+         it != objects->end();
+         it++)
+    {
+        Object * o = (Object *) (*it)->getUserData();
+        ret->push_back(o->getID());
+    }
     return ret;
 }
 
@@ -1130,6 +1139,7 @@ Engine::Object::Object(bool is_static, bool is_reference,
     else
     {
         m_ode_object = world.createObject(is_static, scale);
+        m_ode_object->setUserData(this);
     }
     m_is_static = is_static;
     m_display_list = obj->render();
@@ -1167,6 +1177,7 @@ Engine::Object::Object(bool is_static, bool is_reference, OdeWorld & world,
     else
     {
         m_ode_object = world.createObject(m_is_static, m_scale);
+        m_ode_object->setUserData(this);
     }
     m_is_managed = true;
     m_geom_type = geom_type;
@@ -1215,6 +1226,7 @@ Engine::Object::Object(const Engine::Object & orig)
     {
         m_ode_object = new OdeWorld::Object(*orig.m_ode_object);
     }
+    m_ode_object->setUserData(this);
     if (m_is_managed)
     {
         createManagedObject();
diff --git a/Engine.h b/Engine.h
index 66bcaf8..3884074 100644
--- a/Engine.h
+++ b/Engine.h
@@ -89,6 +89,8 @@ class Engine
                     if (m_ode_object != NULL)
                         m_ode_object->setGravityMode(enabled);
                 }
+                void setID(int id) { m_id = id; }
+                int getID() { return m_id; }
 
             protected:
                 void createManagedObject();
@@ -108,6 +110,7 @@ class Engine
                 dReal m_mass;
                 bool m_mass_is_set;
                 bool m_gravity_mode;
+                int m_id;
 
                 /* for "pre-loaded" objects */
                 int * m_display_list_refcnt;