diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/OSSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/OSSL_Api.cs
index 7494b88584..ebd281efd3 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/OSSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/OSSL_Api.cs
@@ -5554,5 +5554,17 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
             DateTime time = TimeZoneInfo.ConvertTime(DateTime.UtcNow, PSTTimeZone);
             return time.TimeOfDay.TotalSeconds;
         }
+
+        public LSL_Rotation osSlerp(LSL_Rotation a, LSL_Rotation b, LSL_Float amount)
+        {
+            if(amount < 0)
+                amount= 0;
+            else if(amount > 1.0)
+                amount = 1.0;
+            a.Normalize();
+            b.Normalize();
+
+            return LSL_Rotation.Slerp(a, b, amount);
+        }
     }
 }
\ No newline at end of file
diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Interface/IOSSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Interface/IOSSL_Api.cs
index 1bd6e086fb..369b361007 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Interface/IOSSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Interface/IOSSL_Api.cs
@@ -36,6 +36,7 @@ using LSL_List = OpenSim.Region.ScriptEngine.Shared.LSL_Types.list;
 using LSL_String = OpenSim.Region.ScriptEngine.Shared.LSL_Types.LSLString;
 using LSL_Integer = OpenSim.Region.ScriptEngine.Shared.LSL_Types.LSLInteger;
 using LSL_Float = OpenSim.Region.ScriptEngine.Shared.LSL_Types.LSLFloat;
+using LSL_Rotation = OpenSim.Region.ScriptEngine.Shared.LSL_Types.Quaternion;
 using LSL_Key = OpenSim.Region.ScriptEngine.Shared.LSL_Types.LSLString;
 
 
@@ -554,5 +555,6 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api.Interfaces
         LSL_String osGetInventoryDesc(LSL_String itemNameOrId);
         LSL_Key osGetLastChangedEventKey();
         LSL_Float osGetPSTWallclock();
+        LSL_Rotation osSlerp(LSL_Rotation a, LSL_Rotation b, LSL_Float amount);
     }
 }
diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/LSL_Constants.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/LSL_Constants.cs
index 3f880e4562..7edda5813e 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/LSL_Constants.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/LSL_Constants.cs
@@ -35,7 +35,7 @@ namespace OpenSim.Region.ScriptEngine.Shared.ScriptBase
     public partial class ScriptBaseClass
     {
         // SCRIPTS CONSTANTS
-        public static readonly LSLInteger OS_APIVERSION = 7;
+        public static readonly LSLInteger OS_APIVERSION = 8;
 
         public static readonly LSLInteger TRUE = 1;
         public static readonly LSLInteger FALSE = 0;
diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/OSSL_Stub.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/OSSL_Stub.cs
index 549047c03d..866a955e4d 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/OSSL_Stub.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Runtime/OSSL_Stub.cs
@@ -1407,5 +1407,10 @@ namespace OpenSim.Region.ScriptEngine.Shared.ScriptBase
             return m_OSSL_Functions.osGetPSTWallclock();
         }
 
+        public rotation osSlerp(rotation a, rotation b, LSL_Float amount)
+        {
+            return m_OSSL_Functions.osSlerp(a, b, amount);
+        }
+
     }
 }
diff --git a/OpenSim/Region/ScriptEngine/Shared/LSL_Types.cs b/OpenSim/Region/ScriptEngine/Shared/LSL_Types.cs
index b52f767f40..40e82044e3 100644
--- a/OpenSim/Region/ScriptEngine/Shared/LSL_Types.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/LSL_Types.cs
@@ -434,6 +434,58 @@ namespace OpenSim.Region.ScriptEngine.Shared
 
                 return this;
             }
+
+            public static Quaternion Slerp(Quaternion q1, Quaternion q2, double amount)
+            {
+                double angle = (q1.x * q2.x) + (q1.y * q2.y) + (q1.z * q2.z) + (q1.s * q2.s);
+
+                if (angle < 0f)
+                {
+                    q1.x = -q1.x;
+                    q1.y = -q1.y;
+                    q1.z = -q1.z;
+                    q1.s = -q1.s;
+                    angle *= -1.0;
+                }
+
+                double scale;
+                double invscale;
+
+                if ((angle + 1f) > 0.05f)
+                {
+                    if ((1f - angle) >= 0.05f)
+                    {
+                        // slerp
+                        double theta = Math.Acos(angle);
+                        double invsintheta = 1.0 / Math.Sin(theta);
+                        scale = Math.Sin(theta * (1.0 - amount)) * invsintheta;
+                        invscale = Math.Sin(theta * amount) * invsintheta;
+                    }
+                    else
+                    {
+                        // lerp
+                        scale = 1.0 - amount;
+                        invscale = amount;
+                    }
+                }
+                else
+                {
+                    q2.x = -q1.y;
+                    q2.y = q1.x;
+                    q2.z = -q1.s;
+                    q2.s = q1.z;
+
+                    scale = Math.Sin(Math.PI * (0.5 - amount));
+                    invscale = Math.Sin(Math.PI * amount);
+                }
+
+                return new Quaternion(
+                    q1.x * scale + q2.x * invscale,
+                    q1.y * scale + q2.y * invscale,
+                    q1.z * scale + q2.z * invscale,
+                    q1.s * scale + q2.s * invscale
+                    );
+            }
             #endregion
 
             #region Overriders