diff --git a/src/DataHandling/Model3D.cpp b/src/DataHandling/Model3D.cpp
index b46e711..bc9fafd 100644
--- a/src/DataHandling/Model3D.cpp
+++ b/src/DataHandling/Model3D.cpp
@@ -53,7 +53,7 @@ void Model3D::draw_model()
 
     for (uint32_t i = 0;i<face_count;i++)
     {
-        Vec3i face = faces[i];
+        Vec3i& face = faces[i];
 
         Vec3i* face_texture;
         if (is_textured)
@@ -68,7 +68,7 @@ void Model3D::draw_model()
 
             if (is_textured)
             {
-                Vec2f vertex_texture = texture_coordinates[face_texture->coordinates[j]];
+                Vec2f& vertex_texture = texture_coordinates[face_texture->coordinates[j]];
                 glTexCoord2f(vertex_texture.x,vertex_texture.y);
             }
             glVertex3f(vertex.x,vertex.y,vertex.z);
diff --git a/src/Vectors.h b/src/Vectors.h
index e9c5a5b..29bdf82 100644
--- a/src/Vectors.h
+++ b/src/Vectors.h
@@ -18,7 +18,7 @@ struct CoordinatesVector
 
     /// Computes the euclidean norm of the vector.
     /// \return The magnitude.
-    double magnitude()
+    double magnitude() const
     {
         // TODO : Save magnitude if the vector has not been modified.
         double sum_of_squares = 0;
@@ -29,10 +29,12 @@ struct CoordinatesVector
         return sqrt(sum_of_squares);
     }
 
-    // Use SFINAE to allow normalization of floating point
+    // Use SFINAE to allow normalization of floating point.
+    // The template argument is used to force substitution and thus checking the enable_if.
     /// Normalizes the vector using its euclidean norm.
     /// \return Nothing, the vector is normalized in-place.
-    typename std::enable_if<std::is_floating_point<T>::value,void>::type
+    template <typename U = T>
+    typename std::enable_if<std::is_floating_point<U>::value,void>::type
     normalize()
     {
         double norm = magnitude();
@@ -42,6 +44,19 @@ struct CoordinatesVector
         }
     }
 
+
+    template <typename U = T>
+    typename std::enable_if<std::is_arithmetic<U>::value,T>::type
+    dot_product(const CoordinatesVector<T,N>& operand) const
+    {
+        T result = 0;
+        for (unsigned int i = 0;i<N;i++)
+        {
+            result += coordinates[i]*operand.coordinates[i];
+        }
+        return result;
+    }
+
     // Use SFINAE to declare the function if and only if the type is arithmetic
     template <typename Scalar>
     typename std::enable_if<std::is_arithmetic<Scalar>::value,CoordinatesVector<T,N>>::type
@@ -104,6 +119,17 @@ struct Vec2 : public CoordinatesVector<T,2>
 
     Vec2() = default;
 
+    Vec2(T x_axis, T y_axis)
+    {
+        x = x_axis;
+        y = y_axis;
+    }
+
+    Vec2(const Vec2<T>& original): x(CoordinatesVector<T,2>::coordinates[0]), y(CoordinatesVector<T,2>::coordinates[1])
+    {
+        std::copy(std::begin(original.coordinates), std::end(original.coordinates), std::begin(CoordinatesVector<T,2>::coordinates));
+    }
+
     // Cast-copy constructor in order to use the operators of the mother class.
     Vec2(const CoordinatesVector<T,2>& origin)
     {
@@ -133,15 +159,39 @@ struct Vec3 : CoordinatesVector<T,3>
 
     Vec3() = default;
 
-    // Cast-copy constructor in order to use the operators of the mother class.
-    Vec3(const CoordinatesVector<T,3>& origin)
+    Vec3(T x_axis, T y_axis, T z_axis)
     {
-        if (this != &origin)
+        x = x_axis;
+        y = y_axis;
+        z = z_axis;
+    }
+
+    Vec3(const Vec3<T>& original): x(CoordinatesVector<T,3>::coordinates[0]), y(CoordinatesVector<T,3>::coordinates[1]), z(CoordinatesVector<T,3>::coordinates[2])
+    {
+        std::copy(std::begin(original.coordinates), std::end(original.coordinates), std::begin(CoordinatesVector<T,3>::coordinates));
+    }
+
+    // Cast-copy constructor in order to use the operators of the mother class.
+    Vec3(const CoordinatesVector<T,3>& original)
+    {
+        if (this != &original)
         {
-            std::copy(std::begin(origin.coordinates),std::end(origin.coordinates),std::begin(CoordinatesVector<T,2>::coordinates));
+            std::copy(std::begin(original.coordinates), std::end(original.coordinates), std::begin(CoordinatesVector<T,3>::coordinates));
         }
     }
 
+    template <typename U = T>
+    typename std::enable_if<std::is_arithmetic<U>::value,Vec3<T>>::type
+    cross_product(const Vec3<T>& operand) const
+    {
+        Vec3<T> normal_vector{0,0,0};
+        normal_vector.x = y*operand.z - z*operand.y;
+        normal_vector.y = z*operand.x - x*operand.z;
+        normal_vector.z = x*operand.y - y*operand.x;
+
+        return normal_vector;
+    }
+
     Vec3& operator=(const Vec3<T>& original)
     {
         if (this != &original)
diff --git a/src/main.cpp b/src/main.cpp
index 3195bc4..c36a79c 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -21,6 +21,11 @@ void manage_inputs()
     {
         glClearColor(0.5,0,0,1);
     }
+    else if (KeyStateManager::is_key_pressed(0x1B))
+    {
+        glutDestroyWindow(glutGetWindow());
+        exit(EXIT_SUCCESS);
+    }
     else
     {
         glClearColor(0,0,0,1);