1 files changed, 1053 insertions, 85 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSShapes.cs b/OpenSim/Region/Physics/BulletSPlugin/BSShapes.cs
index ee18379..5a0a14c 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BSShapes.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSShapes.cs
@@ -29,115 +29,312 @@ using System;
 using System.Collections.Generic;
 using System.Text;
 
+using OpenSim.Framework;
+using OpenSim.Region.Physics.Manager;
+using OpenSim.Region.Physics.Meshing;
+using OpenSim.Region.Physics.ConvexDecompositionDotNet;
+
 using OMV = OpenMetaverse;
 
 namespace OpenSim.Region.Physics.BulletSPlugin
 {
 public abstract class BSShape
 {
+    private static string LogHeader = "[BULLETSIM SHAPE]";
+
     public int referenceCount { get; set; }
     public DateTime lastReferenced { get; set; }
+    public BulletShape physShapeInfo { get; set; }
 
     public BSShape()
     {
-        referenceCount = 0;
+        referenceCount = 1;
         lastReferenced = DateTime.Now;
+        physShapeInfo = new BulletShape();
     }
-
-    // Get a reference to a physical shape. Create if it doesn't exist
-    public static BSShape GetShapeReference(BSScene physicsScene, bool forceRebuild, BSPhysObject prim)
+    public BSShape(BulletShape pShape)
     {
-        BSShape ret = null;
-
-        if (prim.PreferredPhysicalShape == BSPhysicsShapeType.SHAPE_CAPSULE)
-        {
-            // an avatar capsule is close to a native shape (it is not shared)
-            ret = BSShapeNative.GetReference(physicsScene, prim, BSPhysicsShapeType.SHAPE_CAPSULE,
-                                        FixedShapeKey.KEY_CAPSULE);
-            physicsScene.DetailLog("{0},BSShape.GetShapeReference,avatarCapsule,shape={1}", prim.LocalID, ret);
-        }
-
-        // Compound shapes are handled special as they are rebuilt from scratch.
-        // This isn't too great a hardship since most of the child shapes will have already been created.
-        if (ret == null  && prim.PreferredPhysicalShape == BSPhysicsShapeType.SHAPE_COMPOUND)
-        {
-            // Getting a reference to a compound shape gets you the compound shape with the root prim shape added
-            ret = BSShapeCompound.GetReference(prim);
-            physicsScene.DetailLog("{0},BSShapeCollection.CreateGeom,compoundShape,shape={1}", prim.LocalID, ret);
-        }
-
-        // Avatars have their own unique shape
-        if (ret == null  && prim.PreferredPhysicalShape == BSPhysicsShapeType.SHAPE_AVATAR)
-        {
-            // Getting a reference to a compound shape gets you the compound shape with the root prim shape added
-            ret = BSShapeAvatar.GetReference(prim);
-            physicsScene.DetailLog("{0},BSShapeCollection.CreateGeom,avatarShape,shape={1}", prim.LocalID, ret);
-        }
+        referenceCount = 1;
+        lastReferenced = DateTime.Now;
+        physShapeInfo = pShape;
+    }
 
-        if (ret == null)
-            ret = GetShapeReferenceNonSpecial(physicsScene, forceRebuild, prim);
+    // Get another reference to this shape.
+    public abstract BSShape GetReference(BSScene pPhysicsScene, BSPhysObject pPrim);
 
-        return ret;
-    }
-    public static BSShape GetShapeReferenceNonSpecial(BSScene physicsScene, bool forceRebuild, BSPhysObject prim)
+    // Called when this shape is being used again.
+    // Used internally. External callers should call instance.GetReference() to properly copy/reference
+    //       the shape.
+    protected virtual void IncrementReference()
     {
-        return null;
+        referenceCount++;
+        lastReferenced = DateTime.Now;
     }
-    public static BSShape GetShapeReferenceNonNative(BSScene physicsScene, bool forceRebuild, BSPhysObject prim)
+
+    // Called when this shape is being used again.
+    protected virtual void DecrementReference()
     {
-        return null;
+        referenceCount--;
+        lastReferenced = DateTime.Now;
     }
 
     // Release the use of a physical shape.
     public abstract void Dereference(BSScene physicsScene);
 
-    // All shapes have a static call to get a reference to the physical shape
-    // protected abstract static BSShape GetReference();
+    // Return 'true' if there is an allocated physics physical shape under this class instance.
+    public virtual bool HasPhysicalShape
+    {
+        get
+        {
+            if (physShapeInfo != null)
+                return physShapeInfo.HasPhysicalShape;
+            return false;
+        }
+    }
+    public virtual BSPhysicsShapeType ShapeType
+    {
+        get
+        {
+            BSPhysicsShapeType ret = BSPhysicsShapeType.SHAPE_UNKNOWN;
+            if (physShapeInfo != null && physShapeInfo.HasPhysicalShape)
+                ret = physShapeInfo.shapeType;
+            return ret;
+        }
+    }
 
     // Returns a string for debugging that uniquily identifies the memory used by this instance
     public virtual string AddrString
     {
-        get { return "unknown"; }
+        get
+        {
+            if (physShapeInfo != null)
+                return physShapeInfo.AddrString;
+            return "unknown";
+        }
     }
 
     public override string ToString()
     {
         StringBuilder buff = new StringBuilder();
-        buff.Append("<p=");
-        buff.Append(AddrString);
+        if (physShapeInfo == null)
+        {
+            buff.Append("<noPhys");
+        }
+        else
+        {
+            buff.Append("<phy=");
+            buff.Append(physShapeInfo.ToString());
+        }
         buff.Append(",c=");
         buff.Append(referenceCount.ToString());
         buff.Append(">");
         return buff.ToString();
     }
+
+    #region Common shape routines
+    // Create a hash of all the shape parameters to be used as a key for this particular shape.
+    public static System.UInt64 ComputeShapeKey(OMV.Vector3 size, PrimitiveBaseShape pbs, out float retLod)
+    {
+        // level of detail based on size and type of the object
+        float lod = BSParam.MeshLOD;
+        if (pbs.SculptEntry)
+            lod = BSParam.SculptLOD;
+
+        // Mega prims usually get more detail because one can interact with shape approximations at this size.
+        float maxAxis = Math.Max(size.X, Math.Max(size.Y, size.Z));
+        if (maxAxis > BSParam.MeshMegaPrimThreshold)
+            lod = BSParam.MeshMegaPrimLOD;
+
+        retLod = lod;
+        return pbs.GetMeshKey(size, lod);
+    }
+
+    // The creation of a mesh or hull can fail if an underlying asset is not available.
+    // There are two cases: 1) the asset is not in the cache and it needs to be fetched;
+    //     and 2) the asset cannot be converted (like failed decompression of JPEG2000s).
+    //     The first case causes the asset to be fetched. The second case requires
+    //     us to not loop forever.
+    // Called after creating a physical mesh or hull. If the physical shape was created,
+    //     just return.
+    public static BulletShape VerifyMeshCreated(BSScene physicsScene, BulletShape newShape, BSPhysObject prim)
+    {
+        // If the shape was successfully created, nothing more to do
+        if (newShape.HasPhysicalShape)
+            return newShape;
+
+        // VerifyMeshCreated is called after trying to create the mesh. If we think the asset had been
+        //    fetched but we end up here again, the meshing of the asset must have failed.
+        // Prevent trying to keep fetching the mesh by declaring failure.
+        if (prim.PrimAssetState == BSPhysObject.PrimAssetCondition.Fetched)
+        {
+            prim.PrimAssetState = BSPhysObject.PrimAssetCondition.FailedMeshing;
+            physicsScene.Logger.WarnFormat("{0} Fetched asset would not mesh. prim={1}, texture={2}",
+                                            LogHeader, UsefulPrimInfo(physicsScene, prim), prim.BaseShape.SculptTexture);
+            physicsScene.DetailLog("{0},BSShape.VerifyMeshCreated,setFailed,prim={1},tex={2}",
+                                            prim.LocalID, UsefulPrimInfo(physicsScene, prim), prim.BaseShape.SculptTexture);
+        }
+        else
+        {
+            // If this mesh has an underlying asset and we have not failed getting it before, fetch the asset
+            if (prim.BaseShape.SculptEntry
+                && prim.PrimAssetState != BSPhysObject.PrimAssetCondition.FailedAssetFetch
+                && prim.PrimAssetState != BSPhysObject.PrimAssetCondition.FailedMeshing
+                && prim.PrimAssetState != BSPhysObject.PrimAssetCondition.Waiting
+                && prim.BaseShape.SculptTexture != OMV.UUID.Zero
+                )
+            {
+                physicsScene.DetailLog("{0},BSShape.VerifyMeshCreated,fetchAsset,objNam={1},tex={2}",
+                                            prim.LocalID, prim.PhysObjectName, prim.BaseShape.SculptTexture);
+                // Multiple requestors will know we're waiting for this asset
+                prim.PrimAssetState = BSPhysObject.PrimAssetCondition.Waiting;
+
+                BSPhysObject xprim = prim;
+                Util.FireAndForget(delegate
+                    {
+                        // physicsScene.DetailLog("{0},BSShape.VerifyMeshCreated,inFireAndForget", xprim.LocalID);
+                        RequestAssetDelegate assetProvider = physicsScene.RequestAssetMethod;
+                        if (assetProvider != null)
+                        {
+                            BSPhysObject yprim = xprim; // probably not necessary, but, just in case.
+                            assetProvider(yprim.BaseShape.SculptTexture, delegate(AssetBase asset)
+                            {
+                                // physicsScene.DetailLog("{0},BSShape.VerifyMeshCreated,assetProviderCallback", xprim.LocalID);
+                                bool assetFound = false;
+                                string mismatchIDs = String.Empty;  // DEBUG DEBUG
+                                if (asset != null && yprim.BaseShape.SculptEntry)
+                                {
+                                    if (yprim.BaseShape.SculptTexture.ToString() == asset.ID)
+                                    {
+                                        yprim.BaseShape.SculptData = asset.Data;
+                                        // This will cause the prim to see that the filler shape is not the right
+                                        //    one and try again to build the object.
+                                        // No race condition with the normal shape setting since the rebuild is at taint time.
+                                        yprim.PrimAssetState = BSPhysObject.PrimAssetCondition.Fetched;
+                                        yprim.ForceBodyShapeRebuild(false /* inTaintTime */);
+                                        assetFound = true;
+                                    }
+                                    else
+                                    {
+                                        mismatchIDs = yprim.BaseShape.SculptTexture.ToString() + "/" + asset.ID;
+                                    }
+                                }
+                                if (!assetFound)
+                                {
+                                    yprim.PrimAssetState = BSPhysObject.PrimAssetCondition.FailedAssetFetch;
+                                }
+                                physicsScene.DetailLog("{0},BSShape.VerifyMeshCreated,fetchAssetCallback,found={1},isSculpt={2},ids={3}",
+                                            yprim.LocalID, assetFound, yprim.BaseShape.SculptEntry, mismatchIDs );
+                            });
+                        }
+                        else
+                        {
+                            xprim.PrimAssetState = BSPhysObject.PrimAssetCondition.FailedAssetFetch;
+                            physicsScene.Logger.ErrorFormat("{0} Physical object requires asset but no asset provider. Name={1}",
+                                                        LogHeader, physicsScene.Name);
+                        }
+                    });
+            }
+            else
+            {
+                if (prim.PrimAssetState == BSPhysObject.PrimAssetCondition.FailedAssetFetch)
+                {
+                    physicsScene.Logger.WarnFormat("{0} Mesh failed to fetch asset. prim={1}, texture={2}",
+                                                LogHeader, UsefulPrimInfo(physicsScene, prim), prim.BaseShape.SculptTexture);
+                    physicsScene.DetailLog("{0},BSShape.VerifyMeshCreated,wasFailed,prim={1},tex={2}",
+                                                prim.LocalID, UsefulPrimInfo(physicsScene, prim), prim.BaseShape.SculptTexture);
+                }
+                if (prim.PrimAssetState == BSPhysObject.PrimAssetCondition.FailedMeshing)
+                {
+                    physicsScene.Logger.WarnFormat("{0} Mesh asset would not mesh. prim={1}, texture={2}",
+                                                LogHeader, UsefulPrimInfo(physicsScene, prim), prim.BaseShape.SculptTexture);
+                    physicsScene.DetailLog("{0},BSShape.VerifyMeshCreated,wasFailedMeshing,prim={1},tex={2}",
+                                                prim.LocalID, UsefulPrimInfo(physicsScene, prim), prim.BaseShape.SculptTexture);
+                }
+            }
+         }
+
+        // While we wait for the mesh defining asset to be loaded, stick in a simple box for the object.
+        BSShape fillShape = BSShapeNative.GetReference(physicsScene, prim, BSPhysicsShapeType.SHAPE_BOX, FixedShapeKey.KEY_BOX);
+        physicsScene.DetailLog("{0},BSShape.VerifyMeshCreated,boxTempShape", prim.LocalID);
+
+        return fillShape.physShapeInfo;
+     }
+
+    public static String UsefulPrimInfo(BSScene pScene, BSPhysObject prim)
+    {
+        StringBuilder buff = new StringBuilder(prim.PhysObjectName);
+        buff.Append("/pos=");
+        buff.Append(prim.RawPosition.ToString());
+        if (pScene != null)
+        {
+            buff.Append("/rgn=");
+            buff.Append(pScene.Name);
+        }
+        return buff.ToString();
+    }
+
+    #endregion // Common shape routines
 }
 
+// ============================================================================================================
 public class BSShapeNull : BSShape
 {
     public BSShapeNull() : base()
     {
     }
     public static BSShape GetReference() { return new BSShapeNull();  }
+    public override BSShape GetReference(BSScene pPhysicsScene, BSPhysObject pPrim) { return new BSShapeNull();  }
     public override void Dereference(BSScene physicsScene) { /* The magic of garbage collection will make this go away */ }
 }
 
+// ============================================================================================================
 public class BSShapeNative : BSShape
 {
     private static string LogHeader = "[BULLETSIM SHAPE NATIVE]";
-    public BSShapeNative() : base()
+    public BSShapeNative(BulletShape pShape) : base(pShape)
     {
     }
-    public static BSShape GetReference(BSScene physicsScene, BSPhysObject prim, 
-                    BSPhysicsShapeType shapeType, FixedShapeKey shapeKey) 
+
+    public static BSShape GetReference(BSScene physicsScene, BSPhysObject prim,
+                                            BSPhysicsShapeType shapeType, FixedShapeKey shapeKey)
     {
         // Native shapes are not shared and are always built anew.
-        //return new BSShapeNative(physicsScene, prim, shapeType, shapeKey);
-        return null;
+        return new BSShapeNative(CreatePhysicalNativeShape(physicsScene, prim, shapeType, shapeKey));
     }
 
-    private BSShapeNative(BSScene physicsScene, BSPhysObject prim,
-                    BSPhysicsShapeType shapeType, FixedShapeKey shapeKey)
+    public override BSShape GetReference(BSScene pPhysicsScene, BSPhysObject pPrim)
     {
+        // Native shapes are not shared so we return a new shape.
+        BSShape ret = null;
+        lock (physShapeInfo)
+        {
+            ret = new BSShapeNative(CreatePhysicalNativeShape(pPhysicsScene, pPrim,
+                                        physShapeInfo.shapeType, (FixedShapeKey)physShapeInfo.shapeKey));
+        }
+        return ret;
+    }
+
+    // Make this reference to the physical shape go away since native shapes are not shared.
+    public override void Dereference(BSScene physicsScene)
+    {
+        // Native shapes are not tracked and are released immediately
+        lock (physShapeInfo)
+        {
+            if (physShapeInfo.HasPhysicalShape)
+            {
+                physicsScene.DetailLog("{0},BSShapeNative.Dereference,deleteNativeShape,shape={1}", BSScene.DetailLogZero, this);
+                physicsScene.PE.DeleteCollisionShape(physicsScene.World, physShapeInfo);
+            }
+            physShapeInfo.Clear();
+            // Garbage collection will free up this instance.
+        }
+    }
+
+    private static BulletShape CreatePhysicalNativeShape(BSScene physicsScene, BSPhysObject prim,
+                                            BSPhysicsShapeType shapeType, FixedShapeKey shapeKey)
+    {
+        BulletShape newShape;
+
         ShapeData nativeShapeData = new ShapeData();
         nativeShapeData.Type = shapeType;
         nativeShapeData.ID = prim.LocalID;
@@ -146,84 +343,855 @@ public class BSShapeNative : BSShape
         nativeShapeData.MeshKey = (ulong)shapeKey;
         nativeShapeData.HullKey = (ulong)shapeKey;
 
-       
-        /*
         if (shapeType == BSPhysicsShapeType.SHAPE_CAPSULE)
         {
-            ptr = PhysicsScene.PE.BuildCapsuleShape(physicsScene.World, 1f, 1f, prim.Scale);
-            physicsScene.DetailLog("{0},BSShapeCollection.BuiletPhysicalNativeShape,capsule,scale={1}", prim.LocalID, prim.Scale);
+            newShape = physicsScene.PE.BuildCapsuleShape(physicsScene.World, 1f, 1f, prim.Scale);
+            physicsScene.DetailLog("{0},BSShapeNative,capsule,scale={1}", prim.LocalID, prim.Scale);
         }
         else
         {
-            ptr = PhysicsScene.PE.BuildNativeShape(physicsScene.World, nativeShapeData);
+            newShape = physicsScene.PE.BuildNativeShape(physicsScene.World, nativeShapeData);
         }
-        if (ptr == IntPtr.Zero)
+        if (!newShape.HasPhysicalShape)
         {
             physicsScene.Logger.ErrorFormat("{0} BuildPhysicalNativeShape failed. ID={1}, shape={2}",
                                     LogHeader, prim.LocalID, shapeType);
         }
-        type = shapeType;
-        key = (UInt64)shapeKey;
-         */
-    }
-    // Make this reference to the physical shape go away since native shapes are not shared.
-    public override void Dereference(BSScene physicsScene)
-    {
-        /*
-        // Native shapes are not tracked and are released immediately
-        physicsScene.DetailLog("{0},BSShapeCollection.DereferenceShape,deleteNativeShape,shape={1}", BSScene.DetailLogZero, this);
-        PhysicsScene.PE.DeleteCollisionShape(physicsScene.World, this);
-        ptr = IntPtr.Zero;
-        // Garbage collection will free up this instance.
-         */
+        newShape.shapeType = shapeType;
+        newShape.isNativeShape = true;
+        newShape.shapeKey = (UInt64)shapeKey;
+        return newShape;
     }
+
 }
 
+// ============================================================================================================
 public class BSShapeMesh : BSShape
 {
     private static string LogHeader = "[BULLETSIM SHAPE MESH]";
-    private static Dictionary<System.UInt64, BSShapeMesh> Meshes = new Dictionary<System.UInt64, BSShapeMesh>();
+    public static Dictionary<System.UInt64, BSShapeMesh> Meshes = new Dictionary<System.UInt64, BSShapeMesh>();
 
-    public BSShapeMesh() : base()
+    public BSShapeMesh(BulletShape pShape) : base(pShape)
     {
     }
-    public static BSShape GetReference() { return new BSShapeNull();  }
-    public override void Dereference(BSScene physicsScene) { }
+    public static BSShape GetReference(BSScene physicsScene, bool forceRebuild, BSPhysObject prim)
+    {
+        float lod;
+        System.UInt64 newMeshKey = BSShape.ComputeShapeKey(prim.Size, prim.BaseShape, out lod);
+
+        BSShapeMesh retMesh = null;
+        lock (Meshes)
+        {
+            if (Meshes.TryGetValue(newMeshKey, out retMesh))
+            {
+                // The mesh has already been created. Return a new reference to same.
+                retMesh.IncrementReference();
+            }
+            else
+            {
+                retMesh = new BSShapeMesh(new BulletShape());
+                // An instance of this mesh has not been created. Build and remember same.
+                BulletShape newShape = retMesh.CreatePhysicalMesh(physicsScene, prim, newMeshKey, prim.BaseShape, prim.Size, lod);
+
+                // Check to see if mesh was created (might require an asset).
+                newShape = VerifyMeshCreated(physicsScene, newShape, prim);
+                if (!newShape.isNativeShape
+                            || prim.PrimAssetState == BSPhysObject.PrimAssetCondition.FailedMeshing
+                            || prim.PrimAssetState == BSPhysObject.PrimAssetCondition.FailedAssetFetch)
+                {
+                    // If a mesh was what was created, remember the built shape for later sharing.
+                    // Also note that if meshing failed we put it in the mesh list as there is nothing else to do about the mesh.
+                    Meshes.Add(newMeshKey, retMesh);
+                }
+
+                retMesh.physShapeInfo = newShape;
+            }
+        }
+        physicsScene.DetailLog("{0},BSShapeMesh,getReference,mesh={1},size={2},lod={3}", prim.LocalID, retMesh, prim.Size, lod);
+        return retMesh;
+    }
+    public override BSShape GetReference(BSScene pPhysicsScene, BSPhysObject pPrim)
+    {
+        BSShape ret = null;
+        // If the underlying shape is native, the actual shape has not been build (waiting for asset)
+        //     and we must create a copy of the native shape since they are never shared.
+        if (physShapeInfo.HasPhysicalShape && physShapeInfo.isNativeShape)
+        {
+            // TODO: decide when the native shapes should be freed. Check in Dereference?
+            ret = BSShapeNative.GetReference(pPhysicsScene, pPrim, BSPhysicsShapeType.SHAPE_BOX, FixedShapeKey.KEY_BOX);
+        }
+        else
+        {
+            // Another reference to this shape is just counted.
+            IncrementReference();
+            ret = this;
+        }
+        return ret;
+    }
+    public override void Dereference(BSScene physicsScene)
+    {
+        lock (Meshes)
+        {
+            this.DecrementReference();
+            physicsScene.DetailLog("{0},BSShapeMesh.Dereference,shape={1}", BSScene.DetailLogZero, this);
+            // TODO: schedule aging and destruction of unused meshes.
+        }
+    }
+    // Loop through all the known meshes and return the description based on the physical address.
+    public static bool TryGetMeshByPtr(BulletShape pShape, out BSShapeMesh outMesh)
+    {
+        bool ret = false;
+        BSShapeMesh foundDesc = null;
+        lock (Meshes)
+        {
+            foreach (BSShapeMesh sm in Meshes.Values)
+            {
+                if (sm.physShapeInfo.ReferenceSame(pShape))
+                {
+                    foundDesc = sm;
+                    ret = true;
+                    break;
+                }
+
+            }
+        }
+        outMesh = foundDesc;
+        return ret;
+    }
+
+    public delegate BulletShape CreateShapeCall(BulletWorld world, int indicesCount, int[] indices, int verticesCount, float[] vertices );
+    private BulletShape CreatePhysicalMesh(BSScene physicsScene, BSPhysObject prim, System.UInt64 newMeshKey,
+                                            PrimitiveBaseShape pbs, OMV.Vector3 size, float lod)
+    {
+        return BSShapeMesh.CreatePhysicalMeshShape(physicsScene, prim, newMeshKey, pbs, size, lod,
+                            (w, iC, i, vC, v) => physicsScene.PE.CreateMeshShape(w, iC, i, vC, v) );
+    }
+
+    // Code that uses the mesher to create the index/vertices info for a trimesh shape.
+    // This is used by the passed 'makeShape' call to create the Bullet mesh shape.
+    // The actual build call is passed so this logic can be used by several of the shapes that use a
+    //     simple mesh as their base shape.
+    public static BulletShape CreatePhysicalMeshShape(BSScene physicsScene, BSPhysObject prim, System.UInt64 newMeshKey,
+                                            PrimitiveBaseShape pbs, OMV.Vector3 size, float lod, CreateShapeCall makeShape)
+    {
+        BulletShape newShape = new BulletShape();
+
+        IMesh meshData = null;
+        lock (physicsScene.mesher)
+        {
+            meshData = physicsScene.mesher.CreateMesh(prim.PhysObjectName, pbs, size, lod,
+                                            false,  // say it is not physical so a bounding box is not built
+                                            false,   // do not cache the mesh and do not use previously built versions
+                                            false,
+                                            false
+                                            );
+        }
+
+        if (meshData != null)
+        {
+            if (prim.PrimAssetState == BSPhysObject.PrimAssetCondition.Fetched)
+            {
+                // Release the fetched asset data once it has been used.
+                pbs.SculptData = new byte[0];
+                prim.PrimAssetState = BSPhysObject.PrimAssetCondition.Unknown;
+            }
+
+            int[] indices = meshData.getIndexListAsInt();
+            int realIndicesIndex = indices.Length;
+            float[] verticesAsFloats = meshData.getVertexListAsFloat();
+
+            if (BSParam.ShouldRemoveZeroWidthTriangles)
+            {
+                // Remove degenerate triangles. These are triangles with two of the vertices
+                //    are the same. This is complicated by the problem that vertices are not
+                //    made unique in sculpties so we have to compare the values in the vertex.
+                realIndicesIndex = 0;
+                for (int tri = 0; tri < indices.Length; tri += 3)
+                {
+                    // Compute displacements into vertex array for each vertex of the triangle
+                    int v1 = indices[tri + 0] * 3;
+                    int v2 = indices[tri + 1] * 3;
+                    int v3 = indices[tri + 2] * 3;
+                // Check to see if any two of the vertices are the same
+                    if (!( (  verticesAsFloats[v1 + 0] == verticesAsFloats[v2 + 0]
+                           && verticesAsFloats[v1 + 1] == verticesAsFloats[v2 + 1]
+                           && verticesAsFloats[v1 + 2] == verticesAsFloats[v2 + 2])
+                        || (  verticesAsFloats[v2 + 0] == verticesAsFloats[v3 + 0]
+                           && verticesAsFloats[v2 + 1] == verticesAsFloats[v3 + 1]
+                           && verticesAsFloats[v2 + 2] == verticesAsFloats[v3 + 2])
+                        || (  verticesAsFloats[v1 + 0] == verticesAsFloats[v3 + 0]
+                           && verticesAsFloats[v1 + 1] == verticesAsFloats[v3 + 1]
+                           && verticesAsFloats[v1 + 2] == verticesAsFloats[v3 + 2]) )
+                    )
+                    {
+                        // None of the vertices of the triangles are the same. This is a good triangle;
+                        indices[realIndicesIndex + 0] = indices[tri + 0];
+                        indices[realIndicesIndex + 1] = indices[tri + 1];
+                        indices[realIndicesIndex + 2] = indices[tri + 2];
+                        realIndicesIndex += 3;
+                    }
+                }
+            }
+            physicsScene.DetailLog("{0},BSShapeMesh.CreatePhysicalMesh,key={1},origTri={2},realTri={3},numVerts={4}",
+                        BSScene.DetailLogZero, newMeshKey.ToString("X"), indices.Length / 3, realIndicesIndex / 3, verticesAsFloats.Length / 3);
+
+            if (realIndicesIndex != 0)
+            {
+                newShape = makeShape(physicsScene.World, realIndicesIndex, indices, verticesAsFloats.Length / 3, verticesAsFloats);
+            }
+            else
+            {
+                // Force the asset condition to 'failed' so we won't try to keep fetching and processing this mesh.
+                prim.PrimAssetState = BSPhysObject.PrimAssetCondition.FailedMeshing;
+                physicsScene.Logger.DebugFormat("{0} All mesh triangles degenerate. Prim={1}", LogHeader, UsefulPrimInfo(physicsScene, prim) );
+                physicsScene.DetailLog("{0},BSShapeMesh.CreatePhysicalMesh,allDegenerate,key={1}", prim.LocalID, newMeshKey);
+            }
+        }
+        newShape.shapeKey = newMeshKey;
+
+        return newShape;
+    }
 }
 
+// ============================================================================================================
 public class BSShapeHull : BSShape
 {
     private static string LogHeader = "[BULLETSIM SHAPE HULL]";
-    private static Dictionary<System.UInt64, BSShapeHull> Hulls = new Dictionary<System.UInt64, BSShapeHull>();
+    public static Dictionary<System.UInt64, BSShapeHull> Hulls = new Dictionary<System.UInt64, BSShapeHull>();
 
-    public BSShapeHull() : base()
+    public BSShapeHull(BulletShape pShape) : base(pShape)
     {
     }
-    public static BSShape GetReference() { return new BSShapeNull();  }
-    public override void Dereference(BSScene physicsScene) { }
+    public static BSShape GetReference(BSScene physicsScene, bool forceRebuild, BSPhysObject prim)
+    {
+        float lod;
+        System.UInt64 newHullKey = BSShape.ComputeShapeKey(prim.Size, prim.BaseShape, out lod);
+
+        BSShapeHull retHull = null;
+        lock (Hulls)
+        {
+            if (Hulls.TryGetValue(newHullKey, out retHull))
+            {
+                // The mesh has already been created. Return a new reference to same.
+                retHull.IncrementReference();
+            }
+            else
+            {
+                retHull = new BSShapeHull(new BulletShape());
+                // An instance of this mesh has not been created. Build and remember same.
+                BulletShape newShape = retHull.CreatePhysicalHull(physicsScene, prim, newHullKey, prim.BaseShape, prim.Size, lod);
+
+                // Check to see if hull was created (might require an asset).
+                newShape = VerifyMeshCreated(physicsScene, newShape, prim);
+                if (!newShape.isNativeShape
+                            || prim.PrimAssetState == BSPhysObject.PrimAssetCondition.FailedMeshing
+                            || prim.PrimAssetState == BSPhysObject.PrimAssetCondition.FailedAssetFetch)
+                {
+                    // If a mesh was what was created, remember the built shape for later sharing.
+                    Hulls.Add(newHullKey, retHull);
+                }
+                retHull.physShapeInfo = newShape;
+            }
+        }
+        physicsScene.DetailLog("{0},BSShapeHull,getReference,hull={1},size={2},lod={3}", prim.LocalID, retHull, prim.Size, lod);
+        return retHull;
+    }
+    public override BSShape GetReference(BSScene pPhysicsScene, BSPhysObject pPrim)
+    {
+        BSShape ret = null;
+        // If the underlying shape is native, the actual shape has not been build (waiting for asset)
+        //     and we must create a copy of the native shape since they are never shared.
+        if (physShapeInfo.HasPhysicalShape && physShapeInfo.isNativeShape)
+        {
+            // TODO: decide when the native shapes should be freed. Check in Dereference?
+            ret = BSShapeNative.GetReference(pPhysicsScene, pPrim, BSPhysicsShapeType.SHAPE_BOX, FixedShapeKey.KEY_BOX);
+        }
+        else
+        {
+            // Another reference to this shape is just counted.
+            IncrementReference();
+            ret = this;
+        }
+        return ret;
+    }
+    public override void Dereference(BSScene physicsScene)
+    {
+        lock (Hulls)
+        {
+            this.DecrementReference();
+            physicsScene.DetailLog("{0},BSShapeHull.Dereference,shape={1}", BSScene.DetailLogZero, this);
+            // TODO: schedule aging and destruction of unused meshes.
+        }
+    }
+    List<ConvexResult> m_hulls;
+    private BulletShape CreatePhysicalHull(BSScene physicsScene, BSPhysObject prim, System.UInt64 newHullKey,
+                                            PrimitiveBaseShape pbs, OMV.Vector3 size, float lod)
+    {
+        BulletShape newShape = new BulletShape();
+
+        IMesh meshData = null;
+        List<List<OMV.Vector3>> allHulls = null;
+        lock (physicsScene.mesher)
+        {
+            // Pass true for physicalness as this prevents the creation of bounding box which is not needed
+            meshData = physicsScene.mesher.CreateMesh(prim.PhysObjectName, pbs, size, lod, true /* isPhysical */, false /* shouldCache */, false, false);
+
+            // If we should use the asset's hull info, fetch it out of the locked mesher
+            if (meshData != null && BSParam.ShouldUseAssetHulls)
+            {
+                Meshmerizer realMesher = physicsScene.mesher as Meshmerizer;
+                if (realMesher != null)
+                {
+                    allHulls = realMesher.GetConvexHulls(size);
+                }
+                if (allHulls == null)
+                {
+                    physicsScene.DetailLog("{0},BSShapeHull.CreatePhysicalHull,assetHulls,noAssetHull", prim.LocalID);
+                }
+            }
+        }
+
+        // If there is hull data in the mesh asset, build the hull from that
+        if (allHulls != null && BSParam.ShouldUseAssetHulls)
+        {
+            int hullCount = allHulls.Count;
+            int totalVertices = 1;      // include one for the count of the hulls
+            // Using the structure described for HACD hulls, create the memory sturcture
+            //     to pass the hull data to the creater.
+            foreach (List<OMV.Vector3> hullVerts in allHulls)
+            {
+                totalVertices += 4;                     // add four for the vertex count and centroid
+                totalVertices += hullVerts.Count * 3;   // one vertex is three dimensions
+            }
+            float[] convHulls = new float[totalVertices];
+
+            convHulls[0] = (float)hullCount;
+            int jj = 1;
+            foreach (List<OMV.Vector3> hullVerts in allHulls)
+            {
+                convHulls[jj + 0] = hullVerts.Count;
+                convHulls[jj + 1] = 0f;   // centroid x,y,z
+                convHulls[jj + 2] = 0f;
+                convHulls[jj + 3] = 0f;
+                jj += 4;
+                foreach (OMV.Vector3 oneVert in hullVerts)
+                {
+                    convHulls[jj + 0] = oneVert.X;
+                    convHulls[jj + 1] = oneVert.Y;
+                    convHulls[jj + 2] = oneVert.Z;
+                    jj += 3;
+                }
+            }
+
+            // create the hull data structure in Bullet
+            newShape = physicsScene.PE.CreateHullShape(physicsScene.World, hullCount, convHulls);
+
+            physicsScene.DetailLog("{0},BSShapeHull.CreatePhysicalHull,assetHulls,hulls={1},totVert={2},shape={3}",
+                                        prim.LocalID, hullCount, totalVertices, newShape);
+        }
+
+        // If no hull specified in the asset and we should use Bullet's HACD approximation...
+        if (!newShape.HasPhysicalShape && BSParam.ShouldUseBulletHACD)
+        {
+            // Build the hull shape from an existing mesh shape.
+            // The mesh should have already been created in Bullet.
+            physicsScene.DetailLog("{0},BSShapeHull.CreatePhysicalHull,bulletHACD,entry", prim.LocalID);
+            BSShape meshShape = BSShapeMesh.GetReference(physicsScene, true, prim);
+
+            if (meshShape.physShapeInfo.HasPhysicalShape)
+            {
+                HACDParams parms;
+                parms.maxVerticesPerHull = BSParam.BHullMaxVerticesPerHull;
+                parms.minClusters = BSParam.BHullMinClusters;
+                parms.compacityWeight = BSParam.BHullCompacityWeight;
+                parms.volumeWeight = BSParam.BHullVolumeWeight;
+                parms.concavity = BSParam.BHullConcavity;
+                parms.addExtraDistPoints = BSParam.NumericBool(BSParam.BHullAddExtraDistPoints);
+                parms.addNeighboursDistPoints = BSParam.NumericBool(BSParam.BHullAddNeighboursDistPoints);
+                parms.addFacesPoints = BSParam.NumericBool(BSParam.BHullAddFacesPoints);
+                parms.shouldAdjustCollisionMargin = BSParam.NumericBool(BSParam.BHullShouldAdjustCollisionMargin);
+
+                physicsScene.DetailLog("{0},BSShapeHull.CreatePhysicalHull,hullFromMesh,beforeCall", prim.LocalID, newShape.HasPhysicalShape);
+                newShape = physicsScene.PE.BuildHullShapeFromMesh(physicsScene.World, meshShape.physShapeInfo, parms);
+                physicsScene.DetailLog("{0},BSShapeHull.CreatePhysicalHull,hullFromMesh,shape={1}", prim.LocalID, newShape);
+
+                // Now done with the mesh shape.
+                meshShape.Dereference(physicsScene);
+            }
+            physicsScene.DetailLog("{0},BSShapeHull.CreatePhysicalHull,bulletHACD,exit,hasBody={1}", prim.LocalID, newShape.HasPhysicalShape);
+        }
+
+        // If no other hull specifications, use our HACD hull approximation.
+        if (!newShape.HasPhysicalShape && meshData != null)
+        {
+            if (prim.PrimAssetState == BSPhysObject.PrimAssetCondition.Fetched)
+            {
+                // Release the fetched asset data once it has been used.
+                pbs.SculptData = new byte[0];
+                prim.PrimAssetState = BSPhysObject.PrimAssetCondition.Unknown;
+            }
+
+            int[] indices = meshData.getIndexListAsInt();
+            List<OMV.Vector3> vertices = meshData.getVertexList();
+
+            //format conversion from IMesh format to DecompDesc format
+            List<int> convIndices = new List<int>();
+            List<float3> convVertices = new List<float3>();
+            for (int ii = 0; ii < indices.GetLength(0); ii++)
+            {
+                convIndices.Add(indices[ii]);
+            }
+            foreach (OMV.Vector3 vv in vertices)
+            {
+                convVertices.Add(new float3(vv.X, vv.Y, vv.Z));
+            }
+
+            uint maxDepthSplit = (uint)BSParam.CSHullMaxDepthSplit;
+            if (BSParam.CSHullMaxDepthSplit != BSParam.CSHullMaxDepthSplitForSimpleShapes)
+            {
+                // Simple primitive shapes we know are convex so they are better implemented with
+                //    fewer hulls.
+                // Check for simple shape (prim without cuts) and reduce split parameter if so.
+                if (BSShapeCollection.PrimHasNoCuts(pbs))
+                {
+                    maxDepthSplit = (uint)BSParam.CSHullMaxDepthSplitForSimpleShapes;
+                }
+            }
+
+            // setup and do convex hull conversion
+            m_hulls = new List<ConvexResult>();
+            DecompDesc dcomp = new DecompDesc();
+            dcomp.mIndices = convIndices;
+            dcomp.mVertices = convVertices;
+            dcomp.mDepth = maxDepthSplit;
+            dcomp.mCpercent = BSParam.CSHullConcavityThresholdPercent;
+            dcomp.mPpercent = BSParam.CSHullVolumeConservationThresholdPercent;
+            dcomp.mMaxVertices = (uint)BSParam.CSHullMaxVertices;
+            dcomp.mSkinWidth = BSParam.CSHullMaxSkinWidth;
+            ConvexBuilder convexBuilder = new ConvexBuilder(HullReturn);
+            // create the hull into the _hulls variable
+            convexBuilder.process(dcomp);
+
+            physicsScene.DetailLog("{0},BSShapeCollection.CreatePhysicalHull,key={1},inVert={2},inInd={3},split={4},hulls={5}",
+                                BSScene.DetailLogZero, newHullKey, indices.GetLength(0), vertices.Count, maxDepthSplit, m_hulls.Count);
+
+            // Convert the vertices and indices for passing to unmanaged.
+            // The hull information is passed as a large floating point array.
+            // The format is:
+            //  convHulls[0] = number of hulls
+            //  convHulls[1] = number of vertices in first hull
+            //  convHulls[2] = hull centroid X coordinate
+            //  convHulls[3] = hull centroid Y coordinate
+            //  convHulls[4] = hull centroid Z coordinate
+            //  convHulls[5] = first hull vertex X
+            //  convHulls[6] = first hull vertex Y
+            //  convHulls[7] = first hull vertex Z
+            //  convHulls[8] = second hull vertex X
+            //  ...
+            //  convHulls[n] = number of vertices in second hull
+            //  convHulls[n+1] = second hull centroid X coordinate
+            //  ...
+            //
+            // TODO: is is very inefficient. Someday change the convex hull generator to return
+            //   data structures that do not need to be converted in order to pass to Bullet.
+            //   And maybe put the values directly into pinned memory rather than marshaling.
+            int hullCount = m_hulls.Count;
+            int totalVertices = 1;          // include one for the count of the hulls
+            foreach (ConvexResult cr in m_hulls)
+            {
+                totalVertices += 4;                         // add four for the vertex count and centroid
+                totalVertices += cr.HullIndices.Count * 3;  // we pass just triangles
+            }
+            float[] convHulls = new float[totalVertices];
+
+            convHulls[0] = (float)hullCount;
+            int jj = 1;
+            foreach (ConvexResult cr in m_hulls)
+            {
+                // copy vertices for index access
+                float3[] verts = new float3[cr.HullVertices.Count];
+                int kk = 0;
+                foreach (float3 ff in cr.HullVertices)
+                {
+                    verts[kk++] = ff;
+                }
+
+                // add to the array one hull's worth of data
+                convHulls[jj++] = cr.HullIndices.Count;
+                convHulls[jj++] = 0f;   // centroid x,y,z
+                convHulls[jj++] = 0f;
+                convHulls[jj++] = 0f;
+                foreach (int ind in cr.HullIndices)
+                {
+                    convHulls[jj++] = verts[ind].x;
+                    convHulls[jj++] = verts[ind].y;
+                    convHulls[jj++] = verts[ind].z;
+                }
+            }
+            // create the hull data structure in Bullet
+            newShape = physicsScene.PE.CreateHullShape(physicsScene.World, hullCount, convHulls);
+        }
+        newShape.shapeKey = newHullKey;
+        return newShape;
+    }
+    // Callback from convex hull creater with a newly created hull.
+    // Just add it to our collection of hulls for this shape.
+    private void HullReturn(ConvexResult result)
+    {
+        m_hulls.Add(result);
+        return;
+    }
+    // Loop through all the known hulls and return the description based on the physical address.
+    public static bool TryGetHullByPtr(BulletShape pShape, out BSShapeHull outHull)
+    {
+        bool ret = false;
+        BSShapeHull foundDesc = null;
+        lock (Hulls)
+        {
+            foreach (BSShapeHull sh in Hulls.Values)
+            {
+                if (sh.physShapeInfo.ReferenceSame(pShape))
+                {
+                    foundDesc = sh;
+                    ret = true;
+                    break;
+                }
+
+            }
+        }
+        outHull = foundDesc;
+        return ret;
+    }
 }
 
+// ============================================================================================================
 public class BSShapeCompound : BSShape
 {
     private static string LogHeader = "[BULLETSIM SHAPE COMPOUND]";
-    public BSShapeCompound() : base()
+    public BSShapeCompound(BulletShape pShape) : base(pShape)
     {
     }
-    public static BSShape GetReference(BSPhysObject prim) 
-    { 
-        return new BSShapeNull();
+    public static BSShape GetReference(BSScene physicsScene)
+    {
+        // Base compound shapes are not shared so this returns a raw shape.
+        // A built compound shape can be reused in linksets.
+        return new BSShapeCompound(CreatePhysicalCompoundShape(physicsScene));
+    }
+    public override BSShape GetReference(BSScene physicsScene, BSPhysObject prim)
+    {
+        // Calling this reference means we want another handle to an existing compound shape
+        //     (usually linksets) so return this copy.
+        IncrementReference();
+        return this;
+    }
+    // Dereferencing a compound shape releases the hold on all the child shapes.
+    public override void Dereference(BSScene physicsScene)
+    {
+        lock (physShapeInfo)
+        {
+            this.DecrementReference();
+            physicsScene.DetailLog("{0},BSShapeCompound.Dereference,shape={1}", BSScene.DetailLogZero, this);
+            if (referenceCount <= 0)
+            {
+                if (!physicsScene.PE.IsCompound(physShapeInfo))
+                {
+                    // Failed the sanity check!!
+                    physicsScene.Logger.ErrorFormat("{0} Attempt to free a compound shape that is not compound!! type={1}, ptr={2}",
+                                                LogHeader, physShapeInfo.shapeType, physShapeInfo.AddrString);
+                    physicsScene.DetailLog("{0},BSShapeCollection.DereferenceCompound,notACompoundShape,type={1},ptr={2}",
+                                                BSScene.DetailLogZero, physShapeInfo.shapeType, physShapeInfo.AddrString);
+                    return;
+                }
+
+                int numChildren = physicsScene.PE.GetNumberOfCompoundChildren(physShapeInfo);
+                physicsScene.DetailLog("{0},BSShapeCollection.DereferenceCompound,shape={1},children={2}",
+                                        BSScene.DetailLogZero, physShapeInfo, numChildren);
+
+                // Loop through all the children dereferencing each.
+                for (int ii = numChildren - 1; ii >= 0; ii--)
+                {
+                    BulletShape childShape = physicsScene.PE.RemoveChildShapeFromCompoundShapeIndex(physShapeInfo, ii);
+                    DereferenceAnonCollisionShape(physicsScene, childShape);
+                }
+                physicsScene.PE.DeleteCollisionShape(physicsScene.World, physShapeInfo);
+            }
+        }
+    }
+    private static BulletShape CreatePhysicalCompoundShape(BSScene physicsScene)
+    {
+        BulletShape cShape = physicsScene.PE.CreateCompoundShape(physicsScene.World, false);
+        return cShape;
+    }
+    // Sometimes we have a pointer to a collision shape but don't know what type it is.
+    // Figure out type and call the correct dereference routine.
+    // Called at taint-time.
+    private void DereferenceAnonCollisionShape(BSScene physicsScene, BulletShape pShape)
+    {
+        // TODO: figure a better way to go through all the shape types and find a possible instance.
+        BSShapeMesh meshDesc;
+        if (BSShapeMesh.TryGetMeshByPtr(pShape, out meshDesc))
+        {
+            meshDesc.Dereference(physicsScene);
+        }
+        else
+        {
+            BSShapeHull hullDesc;
+            if (BSShapeHull.TryGetHullByPtr(pShape, out hullDesc))
+            {
+                hullDesc.Dereference(physicsScene);
+            }
+            else
+            {
+                BSShapeConvexHull chullDesc;
+                if (BSShapeConvexHull.TryGetHullByPtr(pShape, out chullDesc))
+                {
+                    chullDesc.Dereference(physicsScene);
+                }
+                else
+                {
+                    BSShapeGImpact gImpactDesc;
+                    if (BSShapeGImpact.TryGetGImpactByPtr(pShape, out gImpactDesc))
+                    {
+                        gImpactDesc.Dereference(physicsScene);
+                    }
+                    else
+                    {
+                        // Didn't find it in the lists of specific types. It could be compound.
+                        if (physicsScene.PE.IsCompound(pShape))
+                        {
+                            BSShapeCompound recursiveCompound = new BSShapeCompound(pShape);
+                            recursiveCompound.Dereference(physicsScene);
+                        }
+                        else
+                        {
+                            // If none of the above, maybe it is a simple native shape.
+                            if (physicsScene.PE.IsNativeShape(pShape))
+                            {
+                                BSShapeNative nativeShape = new BSShapeNative(pShape);
+                                nativeShape.Dereference(physicsScene);
+                            }
+                        }
+                    }
+                }
+            }
+        }
     }
-    public override void Dereference(BSScene physicsScene) { }
 }
 
+// ============================================================================================================
+public class BSShapeConvexHull : BSShape
+{
+    private static string LogHeader = "[BULLETSIM SHAPE CONVEX HULL]";
+    public static Dictionary<System.UInt64, BSShapeConvexHull> ConvexHulls = new Dictionary<System.UInt64, BSShapeConvexHull>();
+
+    public BSShapeConvexHull(BulletShape pShape) : base(pShape)
+    {
+    }
+    public static BSShape GetReference(BSScene physicsScene, bool forceRebuild, BSPhysObject prim)
+    {
+        float lod;
+        System.UInt64 newMeshKey = BSShape.ComputeShapeKey(prim.Size, prim.BaseShape, out lod);
+
+        physicsScene.DetailLog("{0},BSShapeConvexHull,getReference,newKey={1},size={2},lod={3}",
+                                prim.LocalID, newMeshKey.ToString("X"), prim.Size, lod);
+
+        BSShapeConvexHull retConvexHull = null;
+        lock (ConvexHulls)
+        {
+            if (ConvexHulls.TryGetValue(newMeshKey, out retConvexHull))
+            {
+                // The mesh has already been created. Return a new reference to same.
+                retConvexHull.IncrementReference();
+            }
+            else
+            {
+                retConvexHull = new BSShapeConvexHull(new BulletShape());
+                BulletShape convexShape = null;
+
+                // Get a handle to a mesh to build the hull from
+                BSShape baseMesh = BSShapeMesh.GetReference(physicsScene, false /* forceRebuild */, prim);
+                if (baseMesh.physShapeInfo.isNativeShape)
+                {
+                    // We get here if the mesh was not creatable. Could be waiting for an asset from the disk.
+                    // In the short term, we return the native shape and a later ForceBodyShapeRebuild should
+                    //     get back to this code with a buildable mesh.
+                    // TODO: not sure the temp native shape is freed when the mesh is rebuilt. When does this get freed?
+                    convexShape = baseMesh.physShapeInfo;
+                }
+                else
+                {
+                    convexShape = physicsScene.PE.BuildConvexHullShapeFromMesh(physicsScene.World, baseMesh.physShapeInfo);
+                    convexShape.shapeKey = newMeshKey;
+                    ConvexHulls.Add(convexShape.shapeKey, retConvexHull);
+                }
+
+                // Done with the base mesh
+                baseMesh.Dereference(physicsScene);
+
+                retConvexHull.physShapeInfo = convexShape;
+            }
+        }
+        return retConvexHull;
+    }
+    public override BSShape GetReference(BSScene physicsScene, BSPhysObject prim)
+    {
+        // Calling this reference means we want another handle to an existing shape
+        //     (usually linksets) so return this copy.
+        IncrementReference();
+        return this;
+    }
+    // Dereferencing a compound shape releases the hold on all the child shapes.
+    public override void Dereference(BSScene physicsScene)
+    {
+        lock (ConvexHulls)
+        {
+            this.DecrementReference();
+            physicsScene.DetailLog("{0},BSShapeConvexHull.Dereference,shape={1}", BSScene.DetailLogZero, this);
+            // TODO: schedule aging and destruction of unused meshes.
+        }
+    }
+    // Loop through all the known hulls and return the description based on the physical address.
+    public static bool TryGetHullByPtr(BulletShape pShape, out BSShapeConvexHull outHull)
+    {
+        bool ret = false;
+        BSShapeConvexHull foundDesc = null;
+        lock (ConvexHulls)
+        {
+            foreach (BSShapeConvexHull sh in ConvexHulls.Values)
+            {
+                if (sh.physShapeInfo.ReferenceSame(pShape))
+                {
+                    foundDesc = sh;
+                    ret = true;
+                    break;
+                }
+
+            }
+        }
+        outHull = foundDesc;
+        return ret;
+    }
+}
+// ============================================================================================================
+public class BSShapeGImpact : BSShape
+{
+    private static string LogHeader = "[BULLETSIM SHAPE GIMPACT]";
+    public static Dictionary<System.UInt64, BSShapeGImpact> GImpacts = new Dictionary<System.UInt64, BSShapeGImpact>();
+
+    public BSShapeGImpact(BulletShape pShape) : base(pShape)
+    {
+    }
+    public static BSShape GetReference(BSScene physicsScene, bool forceRebuild, BSPhysObject prim)
+    {
+        float lod;
+        System.UInt64 newMeshKey = BSShape.ComputeShapeKey(prim.Size, prim.BaseShape, out lod);
+
+        physicsScene.DetailLog("{0},BSShapeGImpact,getReference,newKey={1},size={2},lod={3}",
+                                prim.LocalID, newMeshKey.ToString("X"), prim.Size, lod);
+
+        BSShapeGImpact retGImpact = null;
+        lock (GImpacts)
+        {
+            if (GImpacts.TryGetValue(newMeshKey, out retGImpact))
+            {
+                // The mesh has already been created. Return a new reference to same.
+                retGImpact.IncrementReference();
+            }
+            else
+            {
+                retGImpact = new BSShapeGImpact(new BulletShape());
+                BulletShape newShape = retGImpact.CreatePhysicalGImpact(physicsScene, prim, newMeshKey, prim.BaseShape, prim.Size, lod);
+
+                // Check to see if mesh was created (might require an asset).
+                newShape = VerifyMeshCreated(physicsScene, newShape, prim);
+                newShape.shapeKey = newMeshKey;
+                if (!newShape.isNativeShape 
+                            || prim.PrimAssetState == BSPhysObject.PrimAssetCondition.FailedMeshing
+                            || prim.PrimAssetState == BSPhysObject.PrimAssetCondition.FailedAssetFetch)
+                {
+                    // If a mesh was what was created, remember the built shape for later sharing.
+                    // Also note that if meshing failed we put it in the mesh list as there is nothing
+                    //         else to do about the mesh.
+                    GImpacts.Add(newMeshKey, retGImpact);
+                }
+
+                retGImpact.physShapeInfo = newShape;
+            }
+        }
+        return retGImpact;
+    }
+
+    private BulletShape CreatePhysicalGImpact(BSScene physicsScene, BSPhysObject prim, System.UInt64 newMeshKey,
+                                            PrimitiveBaseShape pbs, OMV.Vector3 size, float lod)
+    {
+        return BSShapeMesh.CreatePhysicalMeshShape(physicsScene, prim, newMeshKey, pbs, size, lod,
+                            (w, iC, i, vC, v) => physicsScene.PE.CreateGImpactShape(w, iC, i, vC, v) );
+    }
+
+    public override BSShape GetReference(BSScene pPhysicsScene, BSPhysObject pPrim)
+    {
+        BSShape ret = null;
+        // If the underlying shape is native, the actual shape has not been build (waiting for asset)
+        //     and we must create a copy of the native shape since they are never shared.
+        if (physShapeInfo.HasPhysicalShape && physShapeInfo.isNativeShape)
+        {
+            // TODO: decide when the native shapes should be freed. Check in Dereference?
+            ret = BSShapeNative.GetReference(pPhysicsScene, pPrim, BSPhysicsShapeType.SHAPE_BOX, FixedShapeKey.KEY_BOX);
+        }
+        else
+        {
+            // Another reference to this shape is just counted.
+            IncrementReference();
+            ret = this;
+        }
+        return ret;
+    }
+    // Dereferencing a compound shape releases the hold on all the child shapes.
+    public override void Dereference(BSScene physicsScene)
+    {
+        lock (GImpacts)
+        {
+            this.DecrementReference();
+            physicsScene.DetailLog("{0},BSShapeGImpact.Dereference,shape={1}", BSScene.DetailLogZero, this);
+            // TODO: schedule aging and destruction of unused meshes.
+        }
+    }
+    // Loop through all the known hulls and return the description based on the physical address.
+    public static bool TryGetGImpactByPtr(BulletShape pShape, out BSShapeGImpact outHull)
+    {
+        bool ret = false;
+        BSShapeGImpact foundDesc = null;
+        lock (GImpacts)
+        {
+            foreach (BSShapeGImpact sh in GImpacts.Values)
+            {
+                if (sh.physShapeInfo.ReferenceSame(pShape))
+                {
+                    foundDesc = sh;
+                    ret = true;
+                    break;
+                }
+
+            }
+        }
+        outHull = foundDesc;
+        return ret;
+    }
+}
+
+// ============================================================================================================
 public class BSShapeAvatar : BSShape
 {
     private static string LogHeader = "[BULLETSIM SHAPE AVATAR]";
     public BSShapeAvatar() : base()
     {
     }
-    public static BSShape GetReference(BSPhysObject prim) 
-    { 
+    public static BSShape GetReference(BSPhysObject prim)
+    {
+        return new BSShapeNull();
+    }
+    public override BSShape GetReference(BSScene pPhysicsScene, BSPhysObject pPrim)
+    {
         return new BSShapeNull();
     }
     public override void Dereference(BSScene physicsScene) { }