Quaternion Patch

@@ -18,7 +18,7 @@
     /// </summary>
     [Serializable]
     [StructLayout(LayoutKind.Sequential)]
-    public struct Quaternion
+    public struct Quaternion : IEquatable<Quaternion>
     {
         #region Fields
 
@@ -85,6 +85,10 @@
 			{
 				axis = q.XYZ / den;
 			}
+			else
+			{
+				axis = Vector3.UnitX;
+			}
 		}
 
 		#endregion
@@ -172,6 +176,28 @@
 			return left;
 		}
 
+		/// <summary>
+		/// Compares two Quaternions for equality. 
+		/// </summary>
+		/// <param name="left">The first Quaternion to be used in the comparison.</param>
+		/// <param name="right">The second Quaternion to be used in the comparison.</param>
+		/// <returns>True if both Quaternions are equal. Otherwise it returns false.</returns>
+		public static bool operator ==(Quaternion left, Quaternion right)
+		{
+			return left.Equals(right);
+		}
+
+		/// <summary>
+		/// Compares two Quaternions for inequality. 
+		/// </summary>
+		/// <param name="left">The first Quaternion to be used in the comparison.</param>
+		/// <param name="right">The second Quaternion to be used in the comparison.</param>
+		/// <returns>True if both Quaternions are not equal. Otherwise it returns false.</returns>
+		public static bool operator !=(Quaternion left, Quaternion right)
+		{
+			return !left.Equals(right);
+		}
+		
 		[CLSCompliant(false)]
 		unsafe public static explicit operator float*(Quaternion q)
         {
@@ -455,6 +481,37 @@
             return String.Format("V: {0}, W: {1}", XYZ, W);
         }
 
+		/// <summary>
+		/// Compares this Quaternion instance to another Quaternion for equality. 
+		/// </summary>
+		/// <param name="other">The other Quaternion to be used in the comparison.</param>
+		/// <returns>True if both Quaternions are equal. Otherwise it returns false.</returns>
+		public bool Equals(Quaternion other)
+		{
+			return XYZ == other.XYZ
+			&& W == other.W;
+		}
+
+		/// <summary>
+		/// Compares this object instance to another object for equality. 
+		/// </summary>
+		/// <param name="other">The other object to be used in the comparison.</param>
+		/// <returns>True if both objects are Quaternions of equal value. Otherwise it returns false.</returns>
+		public override bool Equals (object o)
+		{
+			if (o is Quaternion == false) return false;
+			return this == (Quaternion)o;
+		}
+
+		/// <summary>
+		/// Provides the hash code for this object. 
+		/// </summary>
+		/// <returns>A hash code formed from the bitwise XOR of this objects members.</returns>
+		public override int GetHashCode ()
+		{
+			return XYZ.GetHashCode() ^ W.GetHashCode();
+		}
+
         #endregion
     }
 }