add 3-p

Assets/Scripts/FlatlandMovement.cs

@@ -295,6 +295,8 @@ public class FlatlandMovement : MonoBehaviour
         FlatlandMovement other = collision.transform.parent.GetComponent<FlatlandMovement>();
 
         Vector3 col = (other.v - this.v);
+
+        var totalThreeMomentum = this.GetThreeMomentum() + other.GetThreeMomentum();
         
         var tmp = collision.GetContact(0).normal;
         tmp = new Vector3(tmp.x, 0, tmp.z);
@@ -333,4 +335,27 @@ public class FlatlandMovement : MonoBehaviour
         alpha -= collisionforce;
         collisionforce = new Vector3(0, 0, 0);
     }
+
+    public double GetEnergy()
+    {
+        return Constants.Gamma(v.magnitude) * mass * Constants.c * Constants.c;
+    }
+
+    public Vector<double> GetThreeMomentum()
+    {
+        var twop = GetTwoMomentum();
+
+        double[] tmp = { GetEnergy() / Constants.c, twop[0], twop[1] };
+
+        var result = V.DenseOfArray(tmp);
+        return result;
+    }
+
+    public Vector<double> GetTwoMomentum()
+    {
+        double[] tmp = {Constants.Gamma(v.magnitude) * mass * v.x, Constants.Gamma(v.magnitude) * mass * v.z};
+        var result = V.DenseOfArray(tmp);
+
+        return result;
+    }
 }