varregion: add varregion and TerrainData use in LLClientView.

Add sending multiple parcel patches and sending patches by avatar
view distance.

2 files changed, 1112 insertions, 109 deletions

diff --git a/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs b/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
index 849fec3..4c0fba5 100644
--- a/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
+++ b/OpenSim/Region/ClientStack/Linden/UDP/LLClientView.cs
@@ -312,6 +312,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         private const float m_sunPainDaHalfOrbitalCutoff = 4.712388980384689858f;
 
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+        private static string LogHeader = "[LLCLIENTVIEW]";
         protected static Dictionary<PacketType, PacketMethod> PacketHandlers = new Dictionary<PacketType, PacketMethod>(); //Global/static handlers for all clients
 
         /// <summary>
@@ -690,12 +691,36 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// <returns>true if the handler was added.  This is currently always the case.</returns>
         public bool AddLocalPacketHandler(PacketType packetType, PacketMethod handler, bool doAsync)
         {
+            return AddLocalPacketHandler(packetType, handler, doAsync, false);
+        }
+
+        /// <summary>
+        /// Add a handler for the given packet type.
+        /// </summary>
+        /// <param name="packetType"></param>
+        /// <param name="handler"></param>
+        /// <param name="doAsync">
+        /// If true, when the packet is received handle it on a different thread.  Whether this is given direct to 
+        /// a threadpool thread or placed in a queue depends on the inEngine parameter.
+        /// </param>
+        /// <param name="inEngine">
+        /// If async is false then this parameter is ignored.
+        /// If async is true and inEngine is false, then the packet is sent directly to a
+        /// threadpool thread. 
+        /// If async is true and inEngine is true, then the packet is sent to the IncomingPacketAsyncHandlingEngine.
+        /// This may result in slower handling but reduces the risk of overloading the simulator when there are many
+        /// simultaneous async requests.
+        /// </param>
+        /// <returns>true if the handler was added.  This is currently always the case.</returns>
+        public bool AddLocalPacketHandler(PacketType packetType, PacketMethod handler, bool doAsync, bool inEngine)
+        {
             bool result = false;
             lock (m_packetHandlers)
             {
                 if (!m_packetHandlers.ContainsKey(packetType))
                 {
-                    m_packetHandlers.Add(packetType, new PacketProcessor() { method = handler, Async = doAsync });
+                    m_packetHandlers.Add(
+                        packetType, new PacketProcessor() { method = handler, Async = doAsync });
                     result = true;
                 }
             }
@@ -1174,11 +1199,14 @@ namespace OpenSim.Region.ClientStack.LindenUDP
 
         /// <summary>
         ///  Send the region heightmap to the client
+        ///  This method is only called when not doing intellegent terrain patch sending and
+        ///  is only called when the scene presence is initially created and sends all of the
+        ///  region's patches to the client.
         /// </summary>
         /// <param name="map">heightmap</param>
         public virtual void SendLayerData(float[] map)
         {
-            Util.FireAndForget(DoSendLayerData, map);
+            Util.FireAndForget(DoSendLayerData, m_scene.Heightmap.GetTerrainData());
 
             // Send it sync, and async. It's not that much data
             // and it improves user experience just so much!
@@ -1191,15 +1219,16 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// <param name="o"></param>
         private void DoSendLayerData(object o)
         {
-            float[] map = LLHeightFieldMoronize((float[])o);
+            TerrainData map = (TerrainData)o;
 
             try
             {
+                // Send LayerData in typerwriter pattern
                 for (int y = 0; y < 16; y++)
                 {
-                    for (int x = 0; x < 16; x+=4)
+                    for (int x = 0; x < 16; x++)
                     {
-                        SendLayerPacket(x, y, map);
+                        SendLayerData(x, y, map);
                     }
                 }
             }
@@ -1209,77 +1238,95 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             }
         }
 
-        /// <summary>
-        /// Sends a set of four patches (x, x+1, ..., x+3) to the client
-        /// </summary>
-        /// <param name="map">heightmap</param>
-        /// <param name="px">X coordinate for patches 0..12</param>
-        /// <param name="py">Y coordinate for patches 0..15</param>
-        private void SendLayerPacket(int x, int y, float[] map)
+        // Legacy form of invocation that passes around a bare data array.
+        // Just ignore what was passed and use the real terrain info that is part of the scene.
+        // As a HORRIBLE kludge in an attempt to not change the definition of IClientAPI, 
+        //    there is a special form for specifying multiple terrain patches to send.
+        //    The form is to pass 'px' as negative the number of patches to send and to
+        //    pass the float array as pairs of patch X and Y coordinates. So, passing 'px'
+        //    as -2 and map= [3, 5, 8, 4] would mean to send two terrain heightmap patches
+        //    and the patches to send are <3,5> and <8,4>.
+        public void SendLayerData(int px, int py, float[] map)
         {
-            int[] patches = new int[4];
-            patches[0] = x + 0 + y * 16;
-            patches[1] = x + 1 + y * 16;
-            patches[2] = x + 2 + y * 16;
-            patches[3] = x + 3 + y * 16;
+            if (px >= 0)
+            {
+                SendLayerData(px, py, m_scene.Heightmap.GetTerrainData());
+            }
+            else
+            {
+                int numPatches = -px;
+                int[] xPatches = new int[numPatches];
+                int[] yPatches = new int[numPatches];
+                for (int pp = 0; pp < numPatches; pp++)
+                {
+                    xPatches[pp] = (int)map[pp * 2];
+                    yPatches[pp] = (int)map[pp * 2 + 1];
+                }
 
-            float[] heightmap = (map.Length == 65536) ?
-                map :
-                LLHeightFieldMoronize(map);
+                // DebugSendingPatches("SendLayerData", xPatches, yPatches);
 
-            try
-            {
-                Packet layerpack = TerrainCompressor.CreateLandPacket(heightmap, patches);
-                OutPacket(layerpack, ThrottleOutPacketType.Land);
+                SendLayerData(xPatches, yPatches, m_scene.Heightmap.GetTerrainData());
             }
-            catch
+        }
+
+        private void DebugSendingPatches(string pWho, int[] pX, int[] pY)
+        {
+            if (m_log.IsDebugEnabled)
             {
-                for (int px = x ; px < x + 4 ; px++)
-                    SendLayerData(px, y, map);
+                int numPatches = pX.Length;
+                string Xs = "";
+                string Ys = "";
+                for (int pp = 0; pp < numPatches; pp++)
+                {
+                    Xs += String.Format("{0}", (int)pX[pp]) + ",";
+                    Ys += String.Format("{0}", (int)pY[pp]) + ",";
+                }
+                m_log.DebugFormat("{0} {1}: numPatches={2}, X={3}, Y={4}", LogHeader, pWho, numPatches, Xs, Ys);
             }
         }
 
         /// <summary>
-        /// Sends a specified patch to a client
+        /// Sends a terrain packet for the point specified.
+        /// This is a legacy call that has refarbed the terrain into a flat map of floats.
+        /// We just use the terrain from the region we know about.
         /// </summary>
         /// <param name="px">Patch coordinate (x) 0..15</param>
         /// <param name="py">Patch coordinate (y) 0..15</param>
         /// <param name="map">heightmap</param>
-        public void SendLayerData(int px, int py, float[] map)
+        public void SendLayerData(int px, int py, TerrainData terrData)
+        {
+            int[] xPatches = new[] { px };
+            int[] yPatches = new[] { py };
+            SendLayerData(xPatches, yPatches, terrData);
+        }
+
+        private void SendLayerData(int[] px, int[] py, TerrainData terrData)
         {
             try
             {
-                int[] patches = new int[] { py * 16 + px };
-                float[] heightmap = (map.Length == 65536) ?
-                    map :
-                    LLHeightFieldMoronize(map);
-
-                LayerDataPacket layerpack = TerrainCompressor.CreateLandPacket(heightmap, patches);
-                
-                // When a user edits the terrain, so much data is sent, the data queues up fast and presents a sub optimal editing experience.  
-                // To alleviate this issue, when the user edits the terrain, we start skipping the queues until they're done editing the terrain.
-                // We also make them unreliable because it's extremely likely that multiple packets will be sent for a terrain patch area 
-                // invalidating previous packets for that area.
-
-                // It's possible for an editing user to flood themselves with edited packets but the majority of use cases are such that only a 
-                // tiny percentage of users will be editing the terrain.     Other, non-editing users will see the edits much slower.
-                
-                // One last note on this topic, by the time users are going to be editing the terrain, it's extremely likely that the sim will 
-                // have rezzed already and therefore this is not likely going to cause any additional issues with lost packets, objects or terrain 
-                // patches.
+                /* test code using the terrain compressor in libOpenMetaverse
+                int[] patchInd = new int[1];
+                patchInd[0] = px + (py * Constants.TerrainPatchSize);
+                LayerDataPacket layerpack = TerrainCompressor.CreateLandPacket(terrData.GetFloatsSerialized(), patchInd);
+                 */
+                // Many, many patches could have been passed to us. Since the patches will be compressed
+                //   into variable sized blocks, we cannot pre-compute how many will fit into one
+                //   packet. While some fancy packing algorithm is possible, 4 seems to always fit.
+                int PatchesAssumedToFit = 4;
+                for (int pcnt = 0; pcnt < px.Length; pcnt += PatchesAssumedToFit)
+                {
+                    int remaining = Math.Min(px.Length - pcnt, PatchesAssumedToFit);
+                    int[] xPatches = new int[remaining];
+                    int[] yPatches = new int[remaining];
+                    for (int ii = 0; ii < remaining; ii++)
+                    {
+                        xPatches[ii] = px[pcnt + ii];
+                        yPatches[ii] = py[pcnt + ii];
+                    }
+                    LayerDataPacket layerpack = OpenSimTerrainCompressor.CreateLandPacket(terrData, xPatches, yPatches);
+                    // DebugSendingPatches("SendLayerDataInternal", xPatches, yPatches);
 
-                // m_justEditedTerrain is volatile, so test once and duplicate two affected statements so we only have one cache miss.
-                if (m_justEditedTerrain)
-                {
-                    layerpack.Header.Reliable = false;
-                    OutPacket(layerpack,
-                               ThrottleOutPacketType.Unknown );
-                }
-                else
-                {
-                    layerpack.Header.Reliable = true;
-                    OutPacket(layerpack,
-                               ThrottleOutPacketType.Task);
+                    SendTheLayerPacket(layerpack);
                 }
             }
             catch (Exception e)
@@ -1288,36 +1335,34 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             }
         }
 
-        /// <summary>
-        /// Munges heightfield into the LLUDP backed in restricted heightfield.
-        /// </summary>
-        /// <param name="map">float array in the base; Constants.RegionSize</param>
-        /// <returns>float array in the base 256</returns>
-        internal float[] LLHeightFieldMoronize(float[] map)
+        // When a user edits the terrain, so much data is sent, the data queues up fast and presents a
+        // sub optimal editing experience. To alleviate this issue, when the user edits the terrain, we
+        // start skipping the queues until they're done editing the terrain. We also make them
+        // unreliable because it's extremely likely that multiple packets will be sent for a terrain patch
+        // area invalidating previous packets for that area.
+
+        // It's possible for an editing user to flood themselves with edited packets but the majority
+        // of use cases are such that only a tiny percentage of users will be editing the terrain.
+        // Other, non-editing users will see the edits much slower.
+        
+        // One last note on this topic, by the time users are going to be editing the terrain, it's
+        // extremely likely that the sim will have rezzed already and therefore this is not likely going
+        // to cause any additional issues with lost packets, objects or terrain patches.
+
+        // m_justEditedTerrain is volatile, so test once and duplicate two affected statements so we
+        //    only have one cache miss.
+        private void SendTheLayerPacket(LayerDataPacket layerpack)
         {
-            if (map.Length == 65536)
-                return map;
+            if (m_justEditedTerrain)
+            {
+                layerpack.Header.Reliable = false;
+                OutPacket(layerpack, ThrottleOutPacketType.Unknown );
+            }
             else
             {
-                float[] returnmap = new float[65536];
-
-                if (map.Length < 65535)
-                {
-                    // rebase the vector stride to 256
-                    for (int i = 0; i < Constants.RegionSize; i++)
-                        Array.Copy(map, i * (int)Constants.RegionSize, returnmap, i * 256, (int)Constants.RegionSize);
-                }
-                else
-                {
-                    for (int i = 0; i < 256; i++)
-                        Array.Copy(map, i * (int)Constants.RegionSize, returnmap, i * 256, 256);
-                }
-
-                //Array.Copy(map,0,returnmap,0,(map.Length < 65536)? map.Length : 65536);
-
-                return returnmap;
+                layerpack.Header.Reliable = true;
+                OutPacket(layerpack, ThrottleOutPacketType.Land);
             }
-
         }
 
         /// <summary>
@@ -1346,21 +1391,22 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         {
             Vector2[] windSpeeds = (Vector2[])o;
             TerrainPatch[] patches = new TerrainPatch[2];
-            patches[0] = new TerrainPatch();
-            patches[0].Data = new float[16 * 16];
-            patches[1] = new TerrainPatch();
-            patches[1].Data = new float[16 * 16];
+            patches[0] = new TerrainPatch { Data = new float[16 * 16] };
+            patches[1] = new TerrainPatch { Data = new float[16 * 16] };
 
-            for (int y = 0; y < 16; y++)
+            for (int x = 0; x < 16 * 16; x++)
             {
-                for (int x = 0; x < 16; x++)
-                {
-                    patches[0].Data[y * 16 + x] = windSpeeds[y * 16 + x].X;
-                    patches[1].Data[y * 16 + x] = windSpeeds[y * 16 + x].Y;
-                }
+                patches[0].Data[x] = windSpeeds[x].X;
+                patches[1].Data[x] = windSpeeds[x].Y;
             }
 
-            LayerDataPacket layerpack = TerrainCompressor.CreateLayerDataPacket(patches, TerrainPatch.LayerType.Wind);
+            byte layerType = (byte)TerrainPatch.LayerType.Wind;
+            if (m_scene.RegionInfo.RegionSizeX > Constants.RegionSize || m_scene.RegionInfo.RegionSizeY > Constants.RegionSize)
+                layerType = (byte)TerrainPatch.LayerType.WindExtended;
+
+            // LayerDataPacket layerpack = TerrainCompressor.CreateLayerDataPacket(patches, (TerrainPatch.LayerType)layerType);
+            LayerDataPacket layerpack = OpenSimTerrainCompressor.CreateLayerDataPacket(patches, layerType,
+                                (int)m_scene.RegionInfo.RegionSizeX, (int)m_scene.RegionInfo.RegionSizeY);
             layerpack.Header.Zerocoded = true;
             OutPacket(layerpack, ThrottleOutPacketType.Wind);
         }
@@ -1384,7 +1430,13 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 }
             }
 
-            LayerDataPacket layerpack = TerrainCompressor.CreateLayerDataPacket(patches, TerrainPatch.LayerType.Cloud);
+            byte layerType = (byte)TerrainPatch.LayerType.Cloud;
+            if (m_scene.RegionInfo.RegionSizeX > Constants.RegionSize || m_scene.RegionInfo.RegionSizeY > Constants.RegionSize)
+                layerType = (byte)TerrainPatch.LayerType.CloudExtended;
+
+            // LayerDataPacket layerpack = TerrainCompressor.CreateLayerDataPacket(patches, (TerrainPatch.LayerType)layerType);
+            LayerDataPacket layerpack = OpenSimTerrainCompressor.CreateLayerDataPacket(patches, layerType,
+                                (int)m_scene.RegionInfo.RegionSizeX, (int)m_scene.RegionInfo.RegionSizeY);
             layerpack.Header.Zerocoded = true;
             OutPacket(layerpack, ThrottleOutPacketType.Cloud);
         }
@@ -1489,10 +1541,9 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 mapReply.Data[i].Access = mapBlocks2[i].Access;
                 mapReply.Data[i].Agents = mapBlocks2[i].Agents;
 
-                // TODO: hookup varregion sim size here
                 mapReply.Size[i] = new MapBlockReplyPacket.SizeBlock();
-                mapReply.Size[i].SizeX = 256;
-                mapReply.Size[i].SizeY = 256;
+                mapReply.Size[i].SizeX = mapBlocks2[i].SizeX;
+                mapReply.Size[i].SizeY = mapBlocks2[i].SizeY;
             }
             OutPacket(mapReply, ThrottleOutPacketType.Land);
         }
@@ -1657,15 +1708,6 @@ namespace OpenSim.Region.ClientStack.LindenUDP
 
         public void SendKillObject(List<uint> localIDs)
         {
-//            foreach (uint id in localIDs)
-//                m_log.DebugFormat("[CLIENT]: Sending KillObjectPacket to {0} for {1} in {2}", Name, id, regionHandle);
-
-            // remove pending entities
-            lock (m_entityProps.SyncRoot)
-                m_entityProps.Remove(localIDs);
-            lock (m_entityUpdates.SyncRoot)
-                m_entityUpdates.Remove(localIDs);
-
             KillObjectPacket kill = (KillObjectPacket)PacketPool.Instance.GetPacket(PacketType.KillObject);
             // TODO: don't create new blocks if recycling an old packet
             kill.ObjectData = new KillObjectPacket.ObjectDataBlock[localIDs.Count];
@@ -9087,6 +9129,19 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             TeleportLocationRequest handlerTeleportLocationRequest = OnTeleportLocationRequest;
             if (handlerTeleportLocationRequest != null)
             {
+                // Adjust teleport location to base of a larger region if requested to teleport to a sub-region
+                uint locX, locY;
+                Util.RegionHandleToWorldLoc(tpLocReq.Info.RegionHandle, out locX, out locY);
+                if ((locX >= m_scene.RegionInfo.WorldLocX)
+                            && (locX < (m_scene.RegionInfo.WorldLocX + m_scene.RegionInfo.RegionSizeX))
+                            && (locY >= m_scene.RegionInfo.WorldLocY)
+                            && (locY < (m_scene.RegionInfo.WorldLocY + m_scene.RegionInfo.RegionSizeY)) )
+                {
+                    tpLocReq.Info.RegionHandle = m_scene.RegionInfo.RegionHandle;
+                    tpLocReq.Info.Position.X += locX - m_scene.RegionInfo.WorldLocX;
+                    tpLocReq.Info.Position.Y += locY - m_scene.RegionInfo.WorldLocY;
+                }
+
                 handlerTeleportLocationRequest(this, tpLocReq.Info.RegionHandle, tpLocReq.Info.Position,
                                                tpLocReq.Info.LookAt, 16);
             }
diff --git a/OpenSim/Region/Framework/Scenes/TerrainCompressor.cs b/OpenSim/Region/Framework/Scenes/TerrainCompressor.cs
new file mode 100644
index 0000000..fc8f8cd
--- /dev/null
+++ b/OpenSim/Region/Framework/Scenes/TerrainCompressor.cs
@@ -0,0 +1,948 @@
+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSimulator Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* Freely adapted from the Aurora version of the terrain compressor.
+ * Copyright (c) Contributors, http://aurora-sim.org/, http://opensimulator.org/
+ */
+
+using System;
+using System.Reflection;
+
+using log4net;
+
+using OpenSim.Framework;
+using OpenSim.Region.Framework;
+using OpenSim.Region.Framework.Scenes;
+
+using OpenMetaverse;
+using OpenMetaverse.Packets;
+
+namespace OpenSim.Region.ClientStack.LindenUDP
+{
+    public static class OpenSimTerrainCompressor
+    {
+//        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+
+#pragma warning disable 414
+        private static string LogHeader = "[TERRAIN COMPRESSOR]";
+#pragma warning restore 414
+
+        public const int END_OF_PATCHES = 97;
+
+        private const float OO_SQRT2 = 0.7071067811865475244008443621049f;
+        private const int STRIDE = 264;
+
+        private const int ZERO_CODE = 0x0;
+        private const int ZERO_EOB = 0x2;
+        private const int POSITIVE_VALUE = 0x6;
+        private const int NEGATIVE_VALUE = 0x7;
+
+        private static readonly float[] DequantizeTable16 =
+            new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+
+        private static readonly float[] DequantizeTable32 =
+            new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+
+        private static readonly float[] CosineTable16 = new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+        //private static readonly float[] CosineTable32 = new float[Constants.TerrainPatchSize * Constants.TerrainPatchSize];
+        private static readonly int[] CopyMatrix16 = new int[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+        private static readonly int[] CopyMatrix32 = new int[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+
+        private static readonly float[] QuantizeTable16 =
+            new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+
+        static OpenSimTerrainCompressor()
+        {
+            // Initialize the decompression tables
+            BuildDequantizeTable16();
+            SetupCosines16();
+            BuildCopyMatrix16();
+            BuildQuantizeTable16();
+        }
+
+        // Used to send cloud and wind patches
+        public static LayerDataPacket CreateLayerDataPacket(TerrainPatch[] patches, byte type, int pRegionSizeX,
+                                                            int pRegionSizeY)
+        {
+            LayerDataPacket layer = new LayerDataPacket {LayerID = {Type = type}};
+
+            TerrainPatch.GroupHeader header = new TerrainPatch.GroupHeader
+                                                  {Stride = STRIDE, PatchSize = Constants.TerrainPatchSize};
+
+            // Should be enough to fit even the most poorly packed data
+            byte[] data = new byte[patches.Length*Constants.TerrainPatchSize*Constants.TerrainPatchSize*2];
+            BitPack bitpack = new BitPack(data, 0);
+            bitpack.PackBits(header.Stride, 16);
+            bitpack.PackBits(header.PatchSize, 8);
+            bitpack.PackBits(type, 8);
+
+            foreach (TerrainPatch t in patches)
+                CreatePatch(bitpack, t.Data, t.X, t.Y, pRegionSizeX, pRegionSizeY);
+
+            bitpack.PackBits(END_OF_PATCHES, 8);
+
+            layer.LayerData.Data = new byte[bitpack.BytePos + 1];
+            Buffer.BlockCopy(bitpack.Data, 0, layer.LayerData.Data, 0, bitpack.BytePos + 1);
+
+            return layer;
+        }
+
+        // Create a land packet for a single patch.
+        public static LayerDataPacket CreateLandPacket(TerrainData terrData, int patchX, int patchY)
+        {
+            int[] xPieces = new int[1];
+            int[] yPieces = new int[1];
+            xPieces[0] = patchX;  // patch X dimension
+            yPieces[0] = patchY;
+
+            return CreateLandPacket(terrData, xPieces, yPieces);
+        }
+
+        public static LayerDataPacket CreateLandPacket(TerrainData terrData, int[] xPieces, int[] yPieces)
+        {
+            byte landPacketType = (byte)TerrainPatch.LayerType.Land;
+            if (terrData.SizeX > Constants.RegionSize || terrData.SizeY > Constants.RegionSize)
+            {
+                landPacketType = (byte)TerrainPatch.LayerType.LandExtended;
+            }
+
+            return CreateLandPacket(terrData, xPieces, yPieces, landPacketType);
+        }
+
+        /// <summary>
+        ///     Creates a LayerData packet for compressed land data given a full
+        ///     simulator heightmap and an array of indices of patches to compress
+        /// </summary>
+        /// <param name="terrData">
+        ///     Terrain data that can result in a meter square heightmap.
+        /// </param>
+        /// <param name="x">
+        ///     Array of indexes in the grid of patches
+        ///     for this simulator.
+        ///     If creating a packet for multiple patches, there will be entries in
+        ///     both the X and Y arrays for each of the patches.
+        ///     For example if patches 1 and 17 are to be sent,
+        ///     x[] = {1,1} and y[] = {0,1} which specifies the patches at
+        ///     indexes <1,0> and <1,1> (presuming the terrain size is 16x16 patches).
+        /// </param>
+        /// <param name="y">
+        ///     Array of indexes in the grid of patches.
+        /// </param>
+        /// <param name="type"></param>
+        /// <returns></returns>
+        public static LayerDataPacket CreateLandPacket(TerrainData terrData, int[] x, int[] y, byte type)
+        {
+            LayerDataPacket layer = new LayerDataPacket {LayerID = {Type = type}};
+
+            TerrainPatch.GroupHeader header = new TerrainPatch.GroupHeader
+                                                  {Stride = STRIDE, PatchSize = Constants.TerrainPatchSize};
+
+            byte[] data = new byte[x.Length * Constants.TerrainPatchSize * Constants.TerrainPatchSize * 2];
+            BitPack bitpack = new BitPack(data, 0);
+            bitpack.PackBits(header.Stride, 16);
+            bitpack.PackBits(header.PatchSize, 8);
+            bitpack.PackBits(type, 8);
+
+            for (int i = 0; i < x.Length; i++)
+                CreatePatchFromHeightmap(bitpack, terrData, x[i], y[i]);
+
+            bitpack.PackBits(END_OF_PATCHES, 8);
+
+            layer.LayerData.Data = new byte[bitpack.BytePos + 1];
+            Buffer.BlockCopy(bitpack.Data, 0, layer.LayerData.Data, 0, bitpack.BytePos + 1);
+
+            return layer;
+        }
+
+        // Unused: left for historical reference.
+        public static void CreatePatch(BitPack output, float[] patchData, int x, int y, int pRegionSizeX, int pRegionSizeY)
+        {
+            TerrainPatch.Header header = PrescanPatch(patchData);
+            header.QuantWBits = 136;
+            if (pRegionSizeX > Constants.RegionSize || pRegionSizeY > Constants.RegionSize)
+            {
+                header.PatchIDs = (y & 0xFFFF);
+                header.PatchIDs += (x << 16);
+            }
+            else
+            {
+                header.PatchIDs = (y & 0x1F);
+                header.PatchIDs += (x << 5);
+            }
+
+            // NOTE: No idea what prequant and postquant should be or what they do
+
+            int wbits;
+            int[] patch = CompressPatch(patchData, header, 10, out wbits);
+            wbits = EncodePatchHeader(output, header, patch, Constants.RegionSize, Constants.RegionSize, wbits);
+            EncodePatch(output, patch, 0, wbits);
+        }
+
+        /// <summary>
+        ///     Add a patch of terrain to a BitPacker
+        /// </summary>
+        /// <param name="output">BitPacker to write the patch to</param>
+        /// <param name="heightmap">
+        ///     Heightmap of the simulator. Presumed to be an sizeX*sizeY array.
+        /// </param>
+        /// <param name="patchX">
+        ///     X offset of the patch to create.
+        /// </param>
+        /// <param name="patchY">
+        ///     Y offset of the patch to create.
+        /// </param>
+        /// <param name="pRegionSizeX"></param>
+        /// <param name="pRegionSizeY"></param>
+        public static void CreatePatchFromHeightmap(BitPack output, TerrainData terrData, int patchX, int patchY)
+        {
+            TerrainPatch.Header header = PrescanPatch(terrData, patchX, patchY);
+            header.QuantWBits = 136;
+
+            // If larger than legacy region size, pack patch X and Y info differently.
+            if (terrData.SizeX > Constants.RegionSize || terrData.SizeY > Constants.RegionSize)
+            {
+                header.PatchIDs = (patchY & 0xFFFF);
+                header.PatchIDs += (patchX << 16);
+            }
+            else
+            {
+                header.PatchIDs = (patchY & 0x1F);
+                header.PatchIDs += (patchX << 5);
+            }
+
+            // m_log.DebugFormat("{0} CreatePatchFromHeightmap. patchX={1}, patchY={2}, DCOffset={3}, range={4}",
+            //                         LogHeader, patchX, patchY, header.DCOffset, header.Range);
+
+            // NOTE: No idea what prequant and postquant should be or what they do
+            int wbits;
+            int[] patch = CompressPatch(terrData, patchX, patchY, header, 10, out wbits);
+            wbits = EncodePatchHeader(output, header, patch, (uint)terrData.SizeX, (uint)terrData.SizeY, wbits);
+            EncodePatch(output, patch, 0, wbits);
+        }
+
+        private static TerrainPatch.Header PrescanPatch(float[] patch)
+        {
+            TerrainPatch.Header header = new TerrainPatch.Header();
+            float zmax = -99999999.0f;
+            float zmin = 99999999.0f;
+
+            for (int i = 0; i < Constants.TerrainPatchSize*Constants.TerrainPatchSize; i++)
+            {
+                float val = patch[i];
+                if (val > zmax) zmax = val;
+                if (val < zmin) zmin = val;
+            }
+
+            header.DCOffset = zmin;
+            header.Range = (int) ((zmax - zmin) + 1.0f);
+
+            return header;
+        }
+
+        // Scan the height info we're returning and return a patch packet header for this patch.
+        private static TerrainPatch.Header PrescanPatch(TerrainData terrData, int patchX, int patchY)
+        {
+            TerrainPatch.Header header = new TerrainPatch.Header();
+            float zmax = -99999999.0f;
+            float zmin = 99999999.0f;
+
+            for (int j = patchY*Constants.TerrainPatchSize; j < (patchY + 1)*Constants.TerrainPatchSize; j++)
+            {
+                for (int i = patchX*Constants.TerrainPatchSize; i < (patchX + 1)*Constants.TerrainPatchSize; i++)
+                {
+                    float val = terrData[i, j];
+                    if (val > zmax) zmax = val;
+                    if (val < zmin) zmin = val;
+                }
+            }
+
+            header.DCOffset = zmin;
+            header.Range = (int)((zmax - zmin) + 1.0f);
+
+            return header;
+        }
+
+        public static TerrainPatch.Header DecodePatchHeader(BitPack bitpack)
+        {
+            TerrainPatch.Header header = new TerrainPatch.Header {QuantWBits = bitpack.UnpackBits(8)};
+
+            // Quantized word bits
+            if (header.QuantWBits == END_OF_PATCHES)
+                return header;
+
+            // DC offset
+            header.DCOffset = bitpack.UnpackFloat();
+
+            // Range
+            header.Range = bitpack.UnpackBits(16);
+
+            // Patch IDs (10 bits)
+            header.PatchIDs = bitpack.UnpackBits(10);
+
+            // Word bits
+            header.WordBits = (uint) ((header.QuantWBits & 0x0f) + 2);
+
+            return header;
+        }
+
+        private static int EncodePatchHeader(BitPack output, TerrainPatch.Header header, int[] patch, uint pRegionSizeX,
+                                             uint pRegionSizeY, int wbits)
+        {
+            /*
+                    int temp;
+                    int wbits = (header.QuantWBits & 0x0f) + 2;
+                    uint maxWbits = (uint)wbits + 5;
+                    uint minWbits = ((uint)wbits >> 1);
+                    int wbitsMaxValue;
+        */
+            // goal is to determ minimum number of bits to use so all data fits
+            /*
+                    wbits = (int)minWbits;
+                    wbitsMaxValue = (1 << wbits);
+
+                    for (int i = 0; i < patch.Length; i++)
+                    {
+                        temp = patch[i];
+                        if (temp != 0)
+                        {
+                            // Get the absolute value
+                            if (temp < 0) temp *= -1;
+
+         no coments..
+
+                            for (int j = (int)maxWbits; j > (int)minWbits; j--)
+                            {
+                                if ((temp & (1 << j)) != 0)
+                                {
+                                    if (j > wbits) wbits = j;
+                                    break;
+                                }
+                            }
+ 
+                            while (temp > wbitsMaxValue)
+                                {
+                                wbits++;
+                                if (wbits == maxWbits)
+                                    goto Done;
+                                wbitsMaxValue = 1 << wbits;
+                                }
+                        }
+                    }
+
+                Done:
+
+                    //            wbits += 1;
+         */
+            // better check
+            if (wbits > 17)
+                wbits = 16;
+            else if (wbits < 3)
+                wbits = 3;
+
+            header.QuantWBits &= 0xf0;
+
+            header.QuantWBits |= (wbits - 2);
+
+            output.PackBits(header.QuantWBits, 8);
+            output.PackFloat(header.DCOffset);
+            output.PackBits(header.Range, 16);
+            if (pRegionSizeX > Constants.RegionSize || pRegionSizeY > Constants.RegionSize)
+                output.PackBits(header.PatchIDs, 32);
+            else
+                output.PackBits(header.PatchIDs, 10);
+
+            return wbits;
+        }
+
+        private static void IDCTColumn16(float[] linein, float[] lineout, int column)
+        {
+            for (int n = 0; n < Constants.TerrainPatchSize; n++)
+            {
+                float total = OO_SQRT2*linein[column];
+
+                for (int u = 1; u < Constants.TerrainPatchSize; u++)
+                {
+                    int usize = u*Constants.TerrainPatchSize;
+                    total += linein[usize + column]*CosineTable16[usize + n];
+                }
+
+                lineout[Constants.TerrainPatchSize*n + column] = total;
+            }
+        }
+
+        private static void IDCTLine16(float[] linein, float[] lineout, int line)
+        {
+            const float oosob = 2.0f/Constants.TerrainPatchSize;
+            int lineSize = line*Constants.TerrainPatchSize;
+
+            for (int n = 0; n < Constants.TerrainPatchSize; n++)
+            {
+                float total = OO_SQRT2*linein[lineSize];
+
+                for (int u = 1; u < Constants.TerrainPatchSize; u++)
+                {
+                    total += linein[lineSize + u]*CosineTable16[u*Constants.TerrainPatchSize + n];
+                }
+
+                lineout[lineSize + n] = total*oosob;
+            }
+        }
+
+/*
+        private static void DCTLine16(float[] linein, float[] lineout, int line)
+        {
+            float total = 0.0f;
+            int lineSize = line * Constants.TerrainPatchSize;
+
+            for (int n = 0; n < Constants.TerrainPatchSize; n++)
+            {
+                total += linein[lineSize + n];
+            }
+
+            lineout[lineSize] = OO_SQRT2 * total;
+
+            int uptr = 0;
+            for (int u = 1; u < Constants.TerrainPatchSize; u++)
+            {
+                total = 0.0f;
+                uptr += Constants.TerrainPatchSize;
+
+                for (int n = 0; n < Constants.TerrainPatchSize; n++)
+                {
+                    total += linein[lineSize + n] * CosineTable16[uptr + n];
+                }
+
+                lineout[lineSize + u] = total;
+            }
+        }
+*/
+
+        private static void DCTLine16(float[] linein, float[] lineout, int line)
+        {
+            // outputs transpose data (lines exchanged with coluns )
+            // so to save a bit of cpu when doing coluns
+            float total = 0.0f;
+            int lineSize = line*Constants.TerrainPatchSize;
+
+            for (int n = 0; n < Constants.TerrainPatchSize; n++)
+            {
+                total += linein[lineSize + n];
+            }
+
+            lineout[line] = OO_SQRT2*total;
+
+            for (int u = Constants.TerrainPatchSize;
+                 u < Constants.TerrainPatchSize*Constants.TerrainPatchSize;
+                 u += Constants.TerrainPatchSize)
+            {
+                total = 0.0f;
+                for (int ptrn = lineSize, ptru = u; ptrn < lineSize + Constants.TerrainPatchSize; ptrn++,ptru++)
+                {
+                    total += linein[ptrn]*CosineTable16[ptru];
+                }
+
+                lineout[line + u] = total;
+            }
+        }
+
+
+        /*
+                private static void DCTColumn16(float[] linein, int[] lineout, int column)
+                {
+                    float total = 0.0f;
+        //            const float oosob = 2.0f / Constants.TerrainPatchSize;
+
+                    for (int n = 0; n < Constants.TerrainPatchSize; n++)
+                    {
+                        total += linein[Constants.TerrainPatchSize * n + column];
+                    }
+
+        //            lineout[CopyMatrix16[column]] = (int)(OO_SQRT2 * total * oosob * QuantizeTable16[column]);
+                    lineout[CopyMatrix16[column]] = (int)(OO_SQRT2 * total * QuantizeTable16[column]);
+
+                    for (int uptr = Constants.TerrainPatchSize; uptr < Constants.TerrainPatchSize * Constants.TerrainPatchSize; uptr += Constants.TerrainPatchSize)
+                    {
+                        total = 0.0f;
+
+                        for (int n = 0; n < Constants.TerrainPatchSize; n++)
+                        {
+                            total += linein[Constants.TerrainPatchSize * n + column] * CosineTable16[uptr + n];
+                        }
+
+        //                lineout[CopyMatrix16[Constants.TerrainPatchSize * u + column]] = (int)(total * oosob * QuantizeTable16[Constants.TerrainPatchSize * u + column]);
+                        lineout[CopyMatrix16[uptr + column]] = (int)(total * QuantizeTable16[uptr + column]);
+                        }
+                }
+
+        private static void DCTColumn16(float[] linein, int[] lineout, int column)
+        {
+            // input columns are in fact stored in lines now
+
+            float total = 0.0f;
+//            const float oosob = 2.0f / Constants.TerrainPatchSize;
+            int inlinesptr = Constants.TerrainPatchSize*column;
+
+            for (int n = 0; n < Constants.TerrainPatchSize; n++)
+            {
+                total += linein[inlinesptr + n];
+            }
+
+            //            lineout[CopyMatrix16[column]] = (int)(OO_SQRT2 * total * oosob * QuantizeTable16[column]);
+            lineout[CopyMatrix16[column]] = (int) (OO_SQRT2*total*QuantizeTable16[column]);
+
+            for (int uptr = Constants.TerrainPatchSize;
+                 uptr < Constants.TerrainPatchSize*Constants.TerrainPatchSize;
+                 uptr += Constants.TerrainPatchSize)
+            {
+                total = 0.0f;
+
+                for (int n = inlinesptr, ptru = uptr; n < inlinesptr + Constants.TerrainPatchSize; n++, ptru++)
+                {
+                    total += linein[n]*CosineTable16[ptru];
+                }
+
+//                lineout[CopyMatrix16[Constants.TerrainPatchSize * u + column]] = (int)(total * oosob * QuantizeTable16[Constants.TerrainPatchSize * u + column]);
+                lineout[CopyMatrix16[uptr + column]] = (int) (total*QuantizeTable16[uptr + column]);
+            }
+        }
+        */
+
+        private static int DCTColumn16Wbits(float[] linein, int[] lineout, int column, int wbits, int maxwbits)
+        {
+            // input columns are in fact stored in lines now
+
+            bool dowbits = wbits != maxwbits;
+            int wbitsMaxValue = 1 << wbits;
+
+            float total = 0.0f;
+            //            const float oosob = 2.0f / Constants.TerrainPatchSize;
+            int inlinesptr = Constants.TerrainPatchSize*column;
+
+            for (int n = 0; n < Constants.TerrainPatchSize; n++)
+            {
+                total += linein[inlinesptr + n];
+            }
+
+            //            lineout[CopyMatrix16[column]] = (int)(OO_SQRT2 * total * oosob * QuantizeTable16[column]);
+            int tmp = (int) (OO_SQRT2*total*QuantizeTable16[column]);
+            lineout[CopyMatrix16[column]] = tmp;
+
+            if (dowbits)
+            {
+                if (tmp < 0) tmp *= -1;
+                while (tmp > wbitsMaxValue)
+                {
+                    wbits++;
+                    wbitsMaxValue = 1 << wbits;
+                    if (wbits == maxwbits)
+                    {
+                        dowbits = false;
+                        break;
+                    }
+                }
+            }
+
+            for (int uptr = Constants.TerrainPatchSize;
+                 uptr < Constants.TerrainPatchSize*Constants.TerrainPatchSize;
+                 uptr += Constants.TerrainPatchSize)
+            {
+                total = 0.0f;
+
+                for (int n = inlinesptr, ptru = uptr; n < inlinesptr + Constants.TerrainPatchSize; n++, ptru++)
+                {
+                    total += linein[n]*CosineTable16[ptru];
+                }
+
+                tmp = (int) (total*QuantizeTable16[uptr + column]);
+                lineout[CopyMatrix16[uptr + column]] = tmp;
+
+                if (dowbits)
+                {
+                    if (tmp < 0) tmp *= -1;
+                    while (tmp > wbitsMaxValue)
+                    {
+                        wbits++;
+                        wbitsMaxValue = 1 << wbits;
+                        if (wbits == maxwbits)
+                        {
+                            dowbits = false;
+                            break;
+                        }
+                    }
+                }
+            }
+            return wbits;
+        }
+
+        public static void DecodePatch(int[] patches, BitPack bitpack, TerrainPatch.Header header, int size)
+        {
+            for (int n = 0; n < size*size; n++)
+            {
+                // ?
+                int temp = bitpack.UnpackBits(1);
+                if (temp != 0)
+                {
+                    // Value or EOB
+                    temp = bitpack.UnpackBits(1);
+                    if (temp != 0)
+                    {
+                        // Value
+                        temp = bitpack.UnpackBits(1);
+                        if (temp != 0)
+                        {
+                            // Negative
+                            temp = bitpack.UnpackBits((int) header.WordBits);
+                            patches[n] = temp*-1;
+                        }
+                        else
+                        {
+                            // Positive
+                            temp = bitpack.UnpackBits((int) header.WordBits);
+                            patches[n] = temp;
+                        }
+                    }
+                    else
+                    {
+                        // Set the rest to zero
+                        // TODO: This might not be necessary
+                        for (int o = n; o < size*size; o++)
+                        {
+                            patches[o] = 0;
+                        }
+                        break;
+                    }
+                }
+                else
+                {
+                    patches[n] = 0;
+                }
+            }
+        }
+
+        private static void EncodePatch(BitPack output, int[] patch, int postquant, int wbits)
+        {
+            int maxwbitssize = (1 << wbits) - 1;
+
+            if (postquant > Constants.TerrainPatchSize*Constants.TerrainPatchSize || postquant < 0)
+            {
+                Logger.Log("Postquant is outside the range of allowed values in EncodePatch()", Helpers.LogLevel.Error);
+                return;
+            }
+
+            if (postquant != 0) patch[Constants.TerrainPatchSize*Constants.TerrainPatchSize - postquant] = 0;
+
+            for (int i = 0; i < Constants.TerrainPatchSize*Constants.TerrainPatchSize; i++)
+            {
+                int temp = patch[i];
+
+                if (temp == 0)
+                {
+                    bool eob = true;
+
+                    for (int j = i; j < Constants.TerrainPatchSize*Constants.TerrainPatchSize - postquant; j++)
+                    {
+                        if (patch[j] != 0)
+                        {
+                            eob = false;
+                            break;
+                        }
+                    }
+
+                    if (eob)
+                    {
+                        output.PackBits(ZERO_EOB, 2);
+                        return;
+                    }
+                    output.PackBits(ZERO_CODE, 1);
+                }
+                else
+                {
+                    if (temp < 0)
+                    {
+                        temp *= -1;
+
+                        if (temp > maxwbitssize) temp = maxwbitssize;
+
+                        output.PackBits(NEGATIVE_VALUE, 3);
+                        output.PackBits(temp, wbits);
+                    }
+                    else
+                    {
+                        if (temp > maxwbitssize) temp = maxwbitssize;
+
+                        output.PackBits(POSITIVE_VALUE, 3);
+                        output.PackBits(temp, wbits);
+                    }
+                }
+            }
+        }
+
+        public static float[] DecompressPatch(int[] patches, TerrainPatch.Header header, TerrainPatch.GroupHeader group)
+        {
+            float[] block = new float[group.PatchSize*group.PatchSize];
+            float[] output = new float[group.PatchSize*group.PatchSize];
+            int prequant = (header.QuantWBits >> 4) + 2;
+            int quantize = 1 << prequant;
+            float ooq = 1.0f/quantize;
+            float mult = ooq*header.Range;
+            float addval = mult*(1 << (prequant - 1)) + header.DCOffset;
+
+            if (group.PatchSize == Constants.TerrainPatchSize)
+            {
+                for (int n = 0; n < Constants.TerrainPatchSize*Constants.TerrainPatchSize; n++)
+                {
+                    block[n] = patches[CopyMatrix16[n]]*DequantizeTable16[n];
+                }
+
+                float[] ftemp = new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+
+                for (int o = 0; o < Constants.TerrainPatchSize; o++)
+                    IDCTColumn16(block, ftemp, o);
+                for (int o = 0; o < Constants.TerrainPatchSize; o++)
+                    IDCTLine16(ftemp, block, o);
+            }
+            else
+            {
+                for (int n = 0; n < Constants.TerrainPatchSize*2*Constants.TerrainPatchSize*2; n++)
+                {
+                    block[n] = patches[CopyMatrix32[n]]*DequantizeTable32[n];
+                }
+
+                Logger.Log("Implement IDCTPatchLarge", Helpers.LogLevel.Error);
+            }
+
+            for (int j = 0; j < block.Length; j++)
+            {
+                output[j] = block[j]*mult + addval;
+            }
+
+            return output;
+        }
+
+        private static int[] CompressPatch(float[] patchData, TerrainPatch.Header header, int prequant, out int wbits)
+        {
+            float[] block = new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+            int wordsize = (prequant - 2) & 0x0f;
+            float oozrange = 1.0f/header.Range;
+            float range = (1 << prequant);
+            float premult = oozrange*range;
+            float sub = (1 << (prequant - 1)) + header.DCOffset*premult;
+
+            header.QuantWBits = wordsize;
+            header.QuantWBits |= wordsize << 4;
+
+            int k = 0;
+            for (int j = 0; j < Constants.TerrainPatchSize; j++)
+            {
+                for (int i = 0; i < Constants.TerrainPatchSize; i++)
+                    block[k++] = patchData[j*Constants.TerrainPatchSize + i]*premult - sub;
+            }
+
+            float[] ftemp = new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+            int[] itemp = new int[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+
+
+            int maxWbits = prequant + 5;
+            wbits = (prequant >> 1);
+
+            for (int o = 0; o < Constants.TerrainPatchSize; o++)
+                DCTLine16(block, ftemp, o);
+            for (int o = 0; o < Constants.TerrainPatchSize; o++)
+                wbits = DCTColumn16Wbits(ftemp, itemp, o, wbits, maxWbits);
+
+            return itemp;
+        }
+
+        private static int[] CompressPatch(float[,] patchData, TerrainPatch.Header header, int prequant, out int wbits)
+        {
+            float[] block = new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+            float oozrange = 1.0f/header.Range;
+            float range = (1 << prequant);
+            float premult = oozrange*range;
+            float sub = (1 << (prequant - 1)) + header.DCOffset*premult;
+            int wordsize = (prequant - 2) & 0x0f;
+
+            header.QuantWBits = wordsize;
+            header.QuantWBits |= wordsize << 4;
+
+            int k = 0;
+            for (int j = 0; j < Constants.TerrainPatchSize; j++)
+            {
+                for (int i = 0; i < Constants.TerrainPatchSize; i++)
+                    block[k++] = patchData[j, i]*premult - sub;
+            }
+
+            float[] ftemp = new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+            int[] itemp = new int[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+
+            int maxWbits = prequant + 5;
+            wbits = (prequant >> 1);
+
+            for (int o = 0; o < Constants.TerrainPatchSize; o++)
+                DCTLine16(block, ftemp, o);
+            for (int o = 0; o < Constants.TerrainPatchSize; o++)
+                wbits = DCTColumn16Wbits(ftemp, itemp, o, wbits, maxWbits);
+
+            return itemp;
+        }
+
+        private static int[] CompressPatch(TerrainData terrData, int patchX, int patchY, TerrainPatch.Header header,
+                                                               int prequant, out int wbits)
+        {
+            float[] block = new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+            int wordsize = prequant;
+            float oozrange = 1.0f/header.Range;
+            float range = (1 << prequant);
+            float premult = oozrange*range;
+            float sub = (1 << (prequant - 1)) + header.DCOffset*premult;
+
+            header.QuantWBits = wordsize - 2;
+            header.QuantWBits |= (prequant - 2) << 4;
+
+            int k = 0;
+
+            int yPatchLimit = patchY >= (terrData.SizeY / Constants.TerrainPatchSize) ?
+                            (terrData.SizeY - Constants.TerrainPatchSize) / Constants.TerrainPatchSize : patchY;
+            yPatchLimit = (yPatchLimit + 1) * Constants.TerrainPatchSize;
+
+            int xPatchLimit = patchX >= (terrData.SizeX / Constants.TerrainPatchSize) ?
+                            (terrData.SizeX - Constants.TerrainPatchSize) / Constants.TerrainPatchSize : patchX;
+            xPatchLimit = (xPatchLimit + 1) * Constants.TerrainPatchSize;
+
+            for (int yy = patchY * Constants.TerrainPatchSize; yy < yPatchLimit; yy++)
+            {
+                for (int xx = patchX * Constants.TerrainPatchSize; xx < xPatchLimit; xx++)
+                {
+                    block[k++] = terrData[xx, yy] * premult - sub;
+                }
+            }
+
+            float[] ftemp = new float[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+            int[] itemp = new int[Constants.TerrainPatchSize*Constants.TerrainPatchSize];
+
+            int maxWbits = prequant + 5;
+            wbits = (prequant >> 1);
+
+            for (int o = 0; o < Constants.TerrainPatchSize; o++)
+                DCTLine16(block, ftemp, o);
+            for (int o = 0; o < Constants.TerrainPatchSize; o++)
+                wbits = DCTColumn16Wbits(ftemp, itemp, o, wbits, maxWbits);
+
+            return itemp;
+        }
+
+        #region Initialization
+
+        private static void BuildDequantizeTable16()
+        {
+            for (int j = 0; j < Constants.TerrainPatchSize; j++)
+            {
+                for (int i = 0; i < Constants.TerrainPatchSize; i++)
+                {
+                    DequantizeTable16[j*Constants.TerrainPatchSize + i] = 1.0f + 2.0f*(i + j);
+                }
+            }
+        }
+
+        private static void BuildQuantizeTable16()
+        {
+            const float oosob = 2.0f/Constants.TerrainPatchSize;
+            for (int j = 0; j < Constants.TerrainPatchSize; j++)
+            {
+                for (int i = 0; i < Constants.TerrainPatchSize; i++)
+                {
+//                    QuantizeTable16[j * Constants.TerrainPatchSize + i] = 1.0f / (1.0f + 2.0f * ((float)i + (float)j));
+                    QuantizeTable16[j*Constants.TerrainPatchSize + i] = oosob/(1.0f + 2.0f*(i + (float) j));
+                }
+            }
+        }
+
+        private static void SetupCosines16()
+        {
+            const float hposz = (float) Math.PI*0.5f/Constants.TerrainPatchSize;
+
+            for (int u = 0; u < Constants.TerrainPatchSize; u++)
+            {
+                for (int n = 0; n < Constants.TerrainPatchSize; n++)
+                {
+                    CosineTable16[u*Constants.TerrainPatchSize + n] = (float) Math.Cos((2.0f*n + 1.0f)*u*hposz);
+                }
+            }
+        }
+
+        private static void BuildCopyMatrix16()
+        {
+            bool diag = false;
+            bool right = true;
+            int i = 0;
+            int j = 0;
+            int count = 0;
+
+            while (i < Constants.TerrainPatchSize && j < Constants.TerrainPatchSize)
+            {
+                CopyMatrix16[j*Constants.TerrainPatchSize + i] = count++;
+
+                if (!diag)
+                {
+                    if (right)
+                    {
+                        if (i < Constants.TerrainPatchSize - 1) i++;
+                        else j++;
+
+                        right = false;
+                        diag = true;
+                    }
+                    else
+                    {
+                        if (j < Constants.TerrainPatchSize - 1) j++;
+                        else i++;
+
+                        right = true;
+                        diag = true;
+                    }
+                }
+                else
+                {
+                    if (right)
+                    {
+                        i++;
+                        j--;
+                        if (i == Constants.TerrainPatchSize - 1 || j == 0) diag = false;
+                    }
+                    else
+                    {
+                        i--;
+                        j++;
+                        if (j == Constants.TerrainPatchSize - 1 || i == 0) diag = false;
+                    }
+                }
+            }
+        }
+
+        #endregion Initialization
+    }
+}