diff --git a/Lighting.java b/Lighting.java
index aea7b3f..05347c0 100644
--- a/Lighting.java
+++ b/Lighting.java
@@ -8,7 +8,7 @@ public class Lighting {
     static final int NONE = 0;
     static final int AMBIENT = 1;
     static final int POINT = 2;
-    List lights;
+    List<Light> lights;
 
     /* Internal Class describing a light source */
     private class Light {
@@ -22,7 +22,7 @@ public class Lighting {
     }
 
     public Lighting() {
-        lights = new LinkedList();
+        lights = new LinkedList<Light>();
     }
 
     /* Adds a new ambient light source of intensity @ia to the environment. */
@@ -54,13 +54,14 @@ public class Lighting {
         double[] litColor = new double[3];
         /* total light intensity */
         double I = 0.0;
-        Iterator it = lights.iterator();
+        Iterator<Light> it = lights.iterator();
         while (it.hasNext()) {
             Light light = (Light) it.next();
             switch (light.type) {
                 case AMBIENT:
-                    /* Ambient light : A COMPLETER */
-                    /* I += ... */
+                    /* Ambient light */
+                    double Ia = light.params[0];
+                    I += Ia * ka;
                     break;
                 case POINT:
                     try {
@@ -68,19 +69,24 @@ public class Lighting {
                         Vector3 e = new Vector3(cameraPosition);
                         e.subtract(position);
                         e.normalize();
+
                         /* vector from point to light */
                         Vector3 l = new Vector3(light.params[0], light.params[1], light.params[2]);
                         l.subtract(position);
                         l.normalize();
+
                         /* half-vector between e and l */
                         Vector3 h = new Vector3(e);
                         h.add(l);
                         h.normalize();
+
                         /* diffuse contribution : A COMPLETER */
-                        /* double Id = ... */
+                        double Id = kd * ...
+
                         /* specular contribution : A COMPLETER */
-                        /* double Is = ... */
-                        /* I += Id + Is; */
+                        double Is = ks * ...
+
+                        I += Id + Is;
                     } catch (InstantiationException ex) {
                         /* should not reach */ } catch (SizeMismatchException ex) {
                         /* should not reach */ }
diff --git a/Mesh.java b/Mesh.java
index 0eef389..5b2df48 100644
--- a/Mesh.java
+++ b/Mesh.java
@@ -120,9 +120,17 @@ public class Mesh {
         try {
             for (int i = 0; i < 3 * getNumFaces(); i += 3) {
 
-                /* A COMPLETER */
+                Vector v0 = vertices[i + 0];
+                Vector v1 = vertices[i + 1];
+                Vector v2 = vertices[i + 2];
 
-                Vector3 n = new Vector3(); // ?
+                Vector3 bidule_gauche = new Vector3(v1);
+                bidule_gauche.subtract(v0);
+
+                Vector3 bidule_droite = new Vector3(v2);
+                bidule_droite.subtract(v0);
+
+                Vector3 n = bidule_gauche.cross(bidule_droite);
 
                 // ajoute la normale calculee a chq sommet de la face
                 for (int j = 0; j < 3; j++) {