BulletSim: complete code for managed code shape and body tracking. Not debugged.

Eliminate some null exceptions created adding the above code.
Add and remove some detailed logging statements.

1 files changed, 547 insertions, 70 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSShapeCollection.cs b/OpenSim/Region/Physics/BulletSPlugin/BSShapeCollection.cs
index eb4b2ad..7470d23 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BSShapeCollection.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSShapeCollection.cs
@@ -1,70 +1,547 @@
-/*

- * 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 copyrightD

- *       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.

- */

-using System;

-using System.Collections.Generic;

-using System.Text;

-using OMV = OpenMetaverse;

-

-namespace OpenSim.Region.Physics.BulletSPlugin

-{

-public class BSShapeCollection : IDisposable

-{

-    protected BSScene PhysicsScene { get; set; }

-

-    public BSShapeCollection(BSScene physScene)

-    {

-        PhysicsScene = physScene;

-    }

-

-    public void Dispose()

-    {

-    }

-

-    // Track another user of a body

-    public void ReferenceBody(BulletBody shape)

-    {

-    }

-

-    // Release the usage of a body

-    public void DereferenceBody(BulletBody shape)

-    {

-    }

-

-    // Track another user of the shape

-    public void ReferenceShape(BulletShape shape)

-    {

-    }

-

-    // Release the usage of a shape

-    public void DereferenceShape(BulletShape shape)

-    {

-    }

-

-

-

-}

-}

+/*
+ * 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 copyrightD
+ *       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.
+ */
+using System;
+using System.Collections.Generic;
+using System.Text;
+using OMV = OpenMetaverse;
+using OpenSim.Framework;
+using OpenSim.Region.Physics.Manager;
+using OpenSim.Region.Physics.ConvexDecompositionDotNet;
+
+namespace OpenSim.Region.Physics.BulletSPlugin
+{
+public class BSShapeCollection : IDisposable
+{
+    protected BSScene PhysicsScene { get; set; }
+
+    private Object m_shapeActivityLock = new Object();
+
+    private struct MeshDesc
+    {
+        public IntPtr Ptr;
+        public int referenceCount;
+        public DateTime lastReferenced;
+        public IMesh meshData;
+    }
+
+    private struct HullDesc
+    {
+        public IntPtr Ptr;
+        public int referenceCount;
+        public DateTime lastReferenced;
+    }
+
+    private Dictionary<ulong, MeshDesc> Meshes = new Dictionary<ulong, MeshDesc>();
+    private Dictionary<ulong, HullDesc> Hulls = new Dictionary<ulong, HullDesc>();
+
+    public BSShapeCollection(BSScene physScene)
+    {
+        PhysicsScene = physScene;
+    }
+
+    public void Dispose()
+    {
+    }
+
+    // Called to update/change the body and shape for an object.
+    // First checks the shape and updates that if necessary then makes
+    //    sure the body is of the right type.
+    // Return 'true' if either the body or the shape changed.
+    // Called at taint-time!!
+    public bool GetBodyAndShape(bool forceRebuild, BulletSim sim, BSPrim prim, ShapeData shapeData, PrimitiveBaseShape pbs)
+    {
+        bool ret = false;
+
+        // Do we have the correct geometry for this type of object?
+        if (CreateGeom(forceRebuild, prim, shapeData, pbs))
+        {
+            // If we had to select a new shape geometry for the object,
+            //    rebuild the body around it.
+            CreateObject(true, prim, PhysicsScene.World, prim.BSShape, shapeData);
+            ret = true;
+        }
+
+        return ret;
+    }
+
+    // Track another user of a body
+    public void ReferenceBody(BulletBody shape)
+    {
+    }
+
+    // Release the usage of a body
+    public void DereferenceBody(BulletBody shape)
+    {
+    }
+
+    // Track another user of the shape
+    public void ReferenceShape(BulletShape shape)
+    {
+        ReferenceShape(shape, null);
+    }
+
+    // Track the datastructures and use count for a shape.
+    // When creating a hull, this is called first to reference the mesh
+    //     and then again to reference the hull.
+    // Meshes and hulls for the same shape have the same hash key.
+    private void ReferenceShape(BulletShape shape, IMesh meshData)
+    {
+        switch (shape.type)
+        {
+            case ShapeData.PhysicsShapeType.SHAPE_MESH:
+                MeshDesc meshDesc;
+                if (Meshes.TryGetValue(shape.shapeKey, out meshDesc))
+                {
+                    // There is an existing instance of this mesh.
+                    meshDesc.referenceCount++;
+                }
+                else
+                {
+                    // This is a new reference to a mesh
+                    meshDesc.Ptr = shape.Ptr;
+                    meshDesc.meshData = meshData;
+                    meshDesc.referenceCount = 1;
+
+                }
+                meshDesc.lastReferenced = System.DateTime.Now;
+                Meshes[shape.shapeKey] = meshDesc;
+                break;
+            case ShapeData.PhysicsShapeType.SHAPE_HULL:
+                HullDesc hullDesc;
+                if (Hulls.TryGetValue(shape.shapeKey, out hullDesc))
+                {
+                    // There is an existing instance of this mesh.
+                    hullDesc.referenceCount++;
+                }
+                else
+                {
+                    // This is a new reference to a mesh
+                    hullDesc.Ptr = shape.Ptr;
+                    hullDesc.referenceCount = 1;
+
+                }
+                hullDesc.lastReferenced = System.DateTime.Now;
+                Hulls[shape.shapeKey] = hullDesc;
+                break;
+            default:
+                break;
+        }
+    }
+
+    // Release the usage of a shape
+    public void DereferenceShape(BulletShape shape)
+    {
+        switch (shape.type)
+        {
+            case ShapeData.PhysicsShapeType.SHAPE_HULL:
+                DereferenceHull(shape);
+                // Hulls also include a mesh
+                DereferenceMesh(shape);
+                break;
+            case ShapeData.PhysicsShapeType.SHAPE_MESH:
+                DereferenceMesh(shape);
+                break;
+            default:
+                break;
+        }
+    }
+
+    // Count down the reference count for a mesh shape
+    private void DereferenceMesh(BulletShape shape)
+    {
+        MeshDesc meshDesc;
+        if (Meshes.TryGetValue(shape.shapeKey, out meshDesc))
+        {
+            meshDesc.referenceCount--;
+            // TODO: release the Bullet storage
+            meshDesc.lastReferenced = System.DateTime.Now;
+            Meshes[shape.shapeKey] = meshDesc;
+        }
+    }
+
+    // Count down the reference count for a hull shape
+    private void DereferenceHull(BulletShape shape)
+    {
+        HullDesc hullDesc;
+        if (Hulls.TryGetValue(shape.shapeKey, out hullDesc))
+        {
+            hullDesc.referenceCount--;
+            // TODO: release the Bullet storage (aging old entries?)
+            hullDesc.lastReferenced = System.DateTime.Now;
+            Hulls[shape.shapeKey] = hullDesc;
+        }
+    }
+
+    // Create the geometry information in Bullet for later use.
+    // The objects needs a hull if it's physical otherwise a mesh is enough.
+    // No locking here because this is done when we know physics is not simulating.
+    // if 'forceRebuild' is true, the geometry is rebuilt. Otherwise a previously built version is used.
+    // Returns 'true' if the geometry was rebuilt.
+    // Called at taint-time!
+    private bool CreateGeom(bool forceRebuild, BSPrim prim, ShapeData shapeData, PrimitiveBaseShape pbs)
+    {
+        bool ret = false;
+        bool haveShape = false;
+        bool nativeShapePossible = true;
+
+        BulletShape newShape = new BulletShape(IntPtr.Zero);
+
+        // If the object is dynamic, it must have a hull shape
+        if (prim.IsPhysical)
+            nativeShapePossible = false;
+
+        // If the prim attributes are simple, this could be a simple Bullet native shape
+        if (nativeShapePossible
+                && ((pbs.SculptEntry && !PhysicsScene.ShouldMeshSculptedPrim)
+                    || (pbs.ProfileBegin == 0 && pbs.ProfileEnd == 0
+                        && pbs.ProfileHollow == 0
+                        && pbs.PathTwist == 0 && pbs.PathTwistBegin == 0
+                        && pbs.PathBegin == 0 && pbs.PathEnd == 0
+                        && pbs.PathTaperX == 0 && pbs.PathTaperY == 0
+                        && pbs.PathScaleX == 100 && pbs.PathScaleY == 100
+                        && pbs.PathShearX == 0 && pbs.PathShearY == 0) ) )
+        {
+            if (pbs.ProfileShape == ProfileShape.HalfCircle && pbs.PathCurve == (byte)Extrusion.Curve1)
+            {
+                haveShape = true;
+                if (forceRebuild || (prim.BSShape.type != ShapeData.PhysicsShapeType.SHAPE_SPHERE))
+                {
+                    DetailLog("{0},BSShapeCollection.CreateGeom,sphere (force={1}", prim.LocalID, forceRebuild);
+                    newShape = AddNativeShapeToPrim(prim, shapeData, ShapeData.PhysicsShapeType.SHAPE_SPHERE);
+
+                    ret = true;
+                }
+            }
+            else
+            {
+                // m_log.DebugFormat("{0}: CreateGeom: Defaulting to box. lid={1}, type={2}, size={3}", LogHeader, LocalID, _shapeType, _size);
+                haveShape = true;
+                if (forceRebuild || (prim.BSShape.type != ShapeData.PhysicsShapeType.SHAPE_BOX))
+                {
+                    DetailLog("{0},BSShapeCollection.CreateGeom,box (force={1})", prim.LocalID, forceRebuild);
+                    newShape = AddNativeShapeToPrim(prim, shapeData, ShapeData.PhysicsShapeType.SHAPE_BOX);
+
+                    ret = true;
+                }
+            }
+        }
+        // If a simple shape isn't happening, create a mesh and possibly a hull
+        if (!haveShape)
+        {
+            if (prim.IsPhysical)
+            {
+                if (forceRebuild || !Hulls.ContainsKey(prim.BSShape.shapeKey))
+                {
+                    // physical objects require a hull for interaction.
+                    // This also creates the mesh if it doesn't already exist
+                    ret = CreateGeomHull(prim, shapeData, pbs);
+                }
+            }
+            else
+            {
+                if (forceRebuild || !Meshes.ContainsKey(prim.BSShape.shapeKey))
+                {
+                    // Static (non-physical) objects only need a mesh for bumping into
+                    ret = CreateGeomMesh(prim, shapeData, pbs);
+                }
+            }
+        }
+        return ret;
+    }
+
+    private BulletShape AddNativeShapeToPrim(BSPrim prim, ShapeData shapeData, ShapeData.PhysicsShapeType shapeType)
+    {
+        BulletShape newShape;
+
+        // Bullet native objects are scaled by the Bullet engine so pass the size in
+        prim.Scale = shapeData.Size;
+
+        // release any previous shape
+        DereferenceShape(prim.BSShape);
+
+        MeshDesc existingShapeDesc;
+        if (Meshes.TryGetValue(shapeData.MeshKey, out existingShapeDesc))
+        {
+            // If there is an existing allocated shape, use it
+            newShape = new BulletShape(existingShapeDesc.Ptr, shapeType);
+        }
+        else
+        {
+            // Shape of this discriptioin is not allocated. Create new.
+            newShape = new BulletShape(
+                        BulletSimAPI.BuildNativeShape2(PhysicsScene.World.Ptr,
+                                    (float)shapeType,
+                                    PhysicsScene.Params.collisionMargin,
+                                    prim.Scale),
+                        shapeType);
+        }
+        newShape.shapeKey = shapeData.MeshKey;
+        ReferenceShape(newShape);
+        prim.BSShape = newShape;
+        return newShape;
+    }
+
+    // No locking here because this is done when we know physics is not simulating
+    // Returns 'true' of a mesh was actually rebuild (we could also have one of these specs).
+    // Called at taint-time!
+    private bool CreateGeomMesh(BSPrim prim, ShapeData shapeData, PrimitiveBaseShape pbs)
+    {
+        BulletShape newShape = new BulletShape(IntPtr.Zero);
+
+        // level of detail based on size and type of the object
+        float lod = PhysicsScene.MeshLOD;
+        if (pbs.SculptEntry) 
+            lod = PhysicsScene.SculptLOD;
+
+        float maxAxis = Math.Max(shapeData.Size.X, Math.Max(shapeData.Size.Y, shapeData.Size.Z));
+        if (maxAxis > PhysicsScene.MeshMegaPrimThreshold) 
+            lod = PhysicsScene.MeshMegaPrimLOD;
+
+        ulong newMeshKey = (ulong)pbs.GetMeshKey(shapeData.Size, lod);
+        // m_log.DebugFormat("{0}: CreateGeomMesh: lID={1}, oldKey={2}, newKey={3}", LogHeader, LocalID, _meshKey, newMeshKey);
+
+        // if this new shape is the same as last time, don't recreate the mesh
+        if (prim.BSShape.shapeKey == newMeshKey) return false;
+
+        DetailLog("{0},BSShapeCollection.CreateGeomMesh,create,key={1}", prim.LocalID, newMeshKey);
+
+        // Since we're recreating new, get rid of the reference to the previous shape
+        DereferenceShape(prim.BSShape);
+
+        IMesh meshData = null;
+        IntPtr meshPtr;
+        MeshDesc meshDesc;
+        if (Meshes.TryGetValue(newMeshKey, out meshDesc))
+        {
+            // If the mesh has already been built just use it.
+            meshPtr = meshDesc.Ptr;
+        }
+        else
+        {
+            // always pass false for physicalness as this creates some sort of bounding box which we don't need
+            meshData = PhysicsScene.mesher.CreateMesh(prim.PhysObjectName, pbs, shapeData.Size, lod, false);
+
+            int[] indices = meshData.getIndexListAsInt();
+            List<OMV.Vector3> vertices = meshData.getVertexList();
+
+            float[] verticesAsFloats = new float[vertices.Count * 3];
+            int vi = 0;
+            foreach (OMV.Vector3 vv in vertices)
+            {
+                verticesAsFloats[vi++] = vv.X;
+                verticesAsFloats[vi++] = vv.Y;
+                verticesAsFloats[vi++] = vv.Z;
+            }
+
+            // m_log.DebugFormat("{0}: CreateGeomMesh: calling CreateMesh. lid={1}, key={2}, indices={3}, vertices={4}", 
+            //                  LogHeader, prim.LocalID, newMeshKey, indices.Length, vertices.Count);
+
+            meshPtr = BulletSimAPI.CreateMeshShape2(PhysicsScene.World.Ptr, 
+                                indices.GetLength(0), indices, vertices.Count, verticesAsFloats);
+        }
+        newShape = new BulletShape(meshPtr, ShapeData.PhysicsShapeType.SHAPE_MESH);
+        newShape.shapeKey = newMeshKey;
+
+        ReferenceShape(newShape, meshData);
+
+        // meshes are already scaled by the meshmerizer
+        prim.Scale = new OMV.Vector3(1f, 1f, 1f);
+        prim.BSShape = newShape;
+        return true;        // 'true' means a new shape has been added to this prim
+    }
+
+    // No locking here because this is done when we know physics is not simulating
+    // Returns 'true' of a mesh was actually rebuild (we could also have one of these specs).
+    List<ConvexResult> m_hulls;
+    private bool CreateGeomHull(BSPrim prim, ShapeData shapeData, PrimitiveBaseShape pbs)
+    {
+        BulletShape newShape;
+
+        float lod = pbs.SculptEntry ? PhysicsScene.SculptLOD : PhysicsScene.MeshLOD;
+        ulong newHullKey = (ulong)pbs.GetMeshKey(shapeData.Size, lod);
+        // m_log.DebugFormat("{0}: CreateGeomHull: lID={1}, oldKey={2}, newKey={3}", LogHeader, LocalID, _hullKey, newHullKey);
+
+        // if the hull hasn't changed, don't rebuild it
+        if (newHullKey == prim.BSShape.shapeKey) return false;
+
+        DetailLog("{0},BSShapeCollection.CreateGeomHull,create,oldKey={1},newKey={2}", prim.LocalID, newHullKey, newHullKey);
+
+        // remove references to any previous shape
+        DereferenceShape(prim.BSShape);
+
+        // Make sure the underlying mesh exists and is correct
+        // Since we're in the hull code, we know CreateGeomMesh() will not create a native shape.
+        CreateGeomMesh(prim, shapeData, pbs);
+        MeshDesc meshDesc = Meshes[newHullKey];
+
+        IntPtr hullPtr;
+        HullDesc hullDesc;
+        if (Hulls.TryGetValue(newHullKey, out hullDesc))
+        {
+            hullPtr = hullDesc.Ptr;
+        }
+        else
+        {
+            int[] indices = meshDesc.meshData.getIndexListAsInt();
+            List<OMV.Vector3> vertices = meshDesc.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));
+            }
+
+            // setup and do convex hull conversion
+            m_hulls = new List<ConvexResult>();
+            DecompDesc dcomp = new DecompDesc();
+            dcomp.mIndices = convIndices;
+            dcomp.mVertices = convVertices;
+            ConvexBuilder convexBuilder = new ConvexBuilder(HullReturn);
+            // create the hull into the _hulls variable
+            convexBuilder.process(dcomp);
+
+            // 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
+            // m_log.DebugFormat("{0}: CreateGeom: calling CreateHull. lid={1}, key={2}, hulls={3}", LogHeader, LocalID, _hullKey, hullCount);
+            hullPtr = BulletSimAPI.CreateHullShape2(PhysicsScene.World.Ptr, hullCount, convHulls);
+        }
+        newShape = new BulletShape(hullPtr, ShapeData.PhysicsShapeType.SHAPE_HULL);
+        newShape.shapeKey = newHullKey;
+
+        ReferenceShape(newShape);
+
+        // meshes are already scaled by the meshmerizer
+        prim.Scale = new OMV.Vector3(1f, 1f, 1f);
+        prim.BSShape = newShape;
+        return true;        // 'true' means a new shape has been added to this prim
+    }
+
+    // Callback from convex hull creater with a newly created hull.
+    // Just add it to the collection of hulls for this shape.
+    private void HullReturn(ConvexResult result)
+    {
+        m_hulls.Add(result);
+        return;
+    }
+
+    // Create an object in Bullet if it has not already been created
+    // No locking here because this is done when the physics engine is not simulating
+    // Returns 'true' if an object was actually created.
+    private bool CreateObject(bool forceRebuild, BSPrim prim, BulletSim sim, BulletShape shape, ShapeData shapeData)
+    {
+        // the mesh or hull must have already been created in Bullet
+        // m_log.DebugFormat("{0}: CreateObject: lID={1}, shape={2}", LogHeader, LocalID, shape.Type);
+
+        DereferenceBody(prim.BSBody);
+
+        BulletBody aBody;
+        IntPtr bodyPtr = IntPtr.Zero;
+        if (prim.IsSolid)
+        {
+            bodyPtr = BulletSimAPI.CreateBodyFromShape2(sim.Ptr, shape.Ptr, shapeData.Position, shapeData.Rotation);
+        }
+        else
+        {
+            bodyPtr = BulletSimAPI.CreateGhostFromShape2(sim.Ptr, shape.Ptr, shapeData.Position, shapeData.Rotation);
+        }
+        aBody = new BulletBody(shapeData.ID, bodyPtr);
+
+        ReferenceBody(aBody);
+
+        prim.BSBody = aBody;
+        return true;
+    }
+
+    private void DetailLog(string msg, params Object[] args)
+    {
+        PhysicsScene.PhysicsLogging.Write(msg, args);
+    }
+
+
+
+
+
+}
+}