// Get a reference to a physical shape. Create if it doesn't exist
        public static BSShape GetShapeReference(BSScene physicsScene, bool forceRebuild, BSPhysObject prim)
        {
            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);
            }

            if (ret == null)
            ret = GetShapeReferenceNonSpecial(physicsScene, forceRebuild, prim);

            return ret;
        }
        // Convert the passed heightmap to mesh information suitable for CreateMeshShape2().
        // Version that handles magnification.
        // Return 'true' if successfully created.
        public static bool ConvertHeightmapToMesh2( BSScene physicsScene,
                                float[] heightMap, int sizeX, int sizeY,    // parameters of incoming heightmap
                                int magnification,                          // number of vertices per heighmap step
                                Vector3 extent,                             // dimensions of the output mesh
                                Vector3 extentBase,                         // base to be added to all vertices
                                out int indicesCountO, out int[] indicesO,
                                out int verticesCountO, out float[] verticesO)
        {
            bool ret = false;

            int indicesCount = 0;
            int verticesCount = 0;
            int[] indices = new int[0];
            float[] vertices = new float[0];

            HeightMapGetter hmap = new HeightMapGetter(heightMap, sizeX, sizeY);

            // The vertices dimension of the output mesh
            int meshX = sizeX * magnification;
            int meshY = sizeY * magnification;
            // The output size of one mesh step
            float meshXStep = extent.X / meshX;
            float meshYStep = extent.Y / meshY;

            // Create an array of vertices that is meshX+1 by meshY+1 (note the loop
            //    from zero to <= meshX). The triangle indices are then generated as two triangles
            //    per heightmap point. There are meshX by meshY of these squares. The extra row and
            //    column of vertices are used to complete the triangles of the last row and column
            //    of the heightmap.
            try
            {
            // Vertices for the output heightmap plus one on the side and bottom to complete triangles
            int totalVertices = (meshX + 1) * (meshY + 1);
            vertices = new float[totalVertices * 3];
            int totalIndices = meshX * meshY * 6;
            indices = new int[totalIndices];

            if (physicsScene != null)
                physicsScene.DetailLog("{0},BSTerrainMesh.ConvertHeightMapToMesh2,inSize={1},outSize={2},totVert={3},totInd={4},extentBase={5}",
                                    BSScene.DetailLogZero, new Vector2(sizeX, sizeY), new Vector2(meshX, meshY),
                                    totalVertices, totalIndices, extentBase);

            float minHeight = float.MaxValue;
            // Note that sizeX+1 vertices are created since there is land between this and the next region.
            // Loop through the output vertices and compute the mediun height in between the input vertices
            for (int yy = 0; yy <= meshY; yy++)
            {
                for (int xx = 0; xx <= meshX; xx++)     // Hint: the "<=" means we go around sizeX + 1 times
                {
                    float offsetY = (float)yy * (float)sizeY / (float)meshY;     // The Y that is closest to the mesh point
                    int stepY = (int)offsetY;
                    float fractionalY = offsetY - (float)stepY;
                    float offsetX = (float)xx * (float)sizeX / (float)meshX;     // The X that is closest to the mesh point
                    int stepX = (int)offsetX;
                    float fractionalX = offsetX - (float)stepX;

                    // physicsScene.DetailLog("{0},BSTerrainMesh.ConvertHeightMapToMesh2,xx={1},yy={2},offX={3},stepX={4},fractX={5},offY={6},stepY={7},fractY={8}",
                    //                 BSScene.DetailLogZero, xx, yy, offsetX, stepX, fractionalX, offsetY, stepY, fractionalY);

                    // get the four corners of the heightmap square the mesh point is in
                    float heightUL = hmap.GetHeight(stepX    , stepY    );
                    float heightUR = hmap.GetHeight(stepX + 1, stepY    );
                    float heightLL = hmap.GetHeight(stepX    , stepY + 1);
                    float heightLR = hmap.GetHeight(stepX + 1, stepY + 1);

                    // bilinear interplolation
                    float height = heightUL * (1 - fractionalX) * (1 - fractionalY)
                                 + heightUR * fractionalX       * (1 - fractionalY)
                                 + heightLL * (1 - fractionalX) * fractionalY
                                 + heightLR * fractionalX       * fractionalY;

                    // physicsScene.DetailLog("{0},BSTerrainMesh.ConvertHeightMapToMesh2,heightUL={1},heightUR={2},heightLL={3},heightLR={4},heightMap={5}",
                    //                 BSScene.DetailLogZero, heightUL, heightUR, heightLL, heightLR, height);

                    minHeight = Math.Min(minHeight, height);

                    vertices[verticesCount + 0] = (float)xx * meshXStep + extentBase.X;
                    vertices[verticesCount + 1] = (float)yy * meshYStep + extentBase.Y;
                    vertices[verticesCount + 2] = height + extentBase.Z;
                    verticesCount += 3;
                }
            }
            // The number of vertices generated
            verticesCount /= 3;

            // Loop through all the heightmap squares and create indices for the two triangles for that square
            for (int yy = 0; yy < meshY; yy++)
            {
                for (int xx = 0; xx < meshX; xx++)
                {
                    int offset = yy * (meshX + 1) + xx;
                    // Each vertices is presumed to be the upper left corner of a box of two triangles
                    indices[indicesCount + 0] = offset;
                    indices[indicesCount + 1] = offset + 1;
                    indices[indicesCount + 2] = offset + meshX + 1; // accounting for the extra column
                    indices[indicesCount + 3] = offset + 1;
                    indices[indicesCount + 4] = offset + meshX + 2;
                    indices[indicesCount + 5] = offset + meshX + 1;
                    indicesCount += 6;
                }
            }

            ret = true;
            }
            catch (Exception e)
            {
            if (physicsScene != null)
                physicsScene.Logger.ErrorFormat("{0} Failed conversion of heightmap to mesh. For={1}/{2}, e={3}",
                                                LogHeader, physicsScene.RegionName, extentBase, e);
            }

            indicesCountO = indicesCount;
            indicesO = indices;
            verticesCountO = verticesCount;
            verticesO = vertices;

            return ret;
        }
        // Convert the passed heightmap to mesh information suitable for CreateMeshShape2().
        // Return 'true' if successfully created.
        public static bool ConvertHeightmapToMesh( BSScene physicsScene,
                                float[] heightMap, int sizeX, int sizeY,    // parameters of incoming heightmap
                                Vector3 extentBase,                         // base to be added to all vertices
                                out int indicesCountO, out int[] indicesO,
                                out int verticesCountO, out float[] verticesO)
        {
            bool ret = false;

            int indicesCount = 0;
            int verticesCount = 0;
            int[] indices = new int[0];
            float[] vertices = new float[0];

            // Simple mesh creation which assumes magnification == 1.
            // TODO: do a more general solution that scales, adds new vertices and smoothes the result.

            // Create an array of vertices that is sizeX+1 by sizeY+1 (note the loop
            //    from zero to <= sizeX). The triangle indices are then generated as two triangles
            //    per heightmap point. There are sizeX by sizeY of these squares. The extra row and
            //    column of vertices are used to complete the triangles of the last row and column
            //    of the heightmap.
            try
            {
            // One vertice per heightmap value plus the vertices off the side and bottom edge.
            int totalVertices = (sizeX + 1) * (sizeY + 1);
            vertices = new float[totalVertices * 3];
            int totalIndices = sizeX * sizeY * 6;
            indices = new int[totalIndices];

            if (physicsScene != null)
                physicsScene.DetailLog("{0},BSTerrainMesh.ConvertHeightMapToMesh,totVert={1},totInd={2},extentBase={3}",
                                    BSScene.DetailLogZero, totalVertices, totalIndices, extentBase);
            float minHeight = float.MaxValue;
            // Note that sizeX+1 vertices are created since there is land between this and the next region.
            for (int yy = 0; yy <= sizeY; yy++)
            {
                for (int xx = 0; xx <= sizeX; xx++)     // Hint: the "<=" means we go around sizeX + 1 times
                {
                    int offset = yy * sizeX + xx;
                    // Extend the height with the height from the last row or column
                    if (yy == sizeY) offset -= sizeX;
                    if (xx == sizeX) offset -= 1;
                    float height = heightMap[offset];
                    minHeight = Math.Min(minHeight, height);
                    vertices[verticesCount + 0] = (float)xx + extentBase.X;
                    vertices[verticesCount + 1] = (float)yy + extentBase.Y;
                    vertices[verticesCount + 2] = height + extentBase.Z;
                    verticesCount += 3;
                }
            }
            verticesCount = verticesCount / 3;

            for (int yy = 0; yy < sizeY; yy++)
            {
                for (int xx = 0; xx < sizeX; xx++)
                {
                    int offset = yy * (sizeX + 1) + xx;
                    // Each vertices is presumed to be the upper left corner of a box of two triangles
                    indices[indicesCount + 0] = offset;
                    indices[indicesCount + 1] = offset + 1;
                    indices[indicesCount + 2] = offset + sizeX + 1; // accounting for the extra column
                    indices[indicesCount + 3] = offset + 1;
                    indices[indicesCount + 4] = offset + sizeX + 2;
                    indices[indicesCount + 5] = offset + sizeX + 1;
                    indicesCount += 6;
                }
            }

            ret = true;
            }
            catch (Exception e)
            {
            if (physicsScene != null)
                physicsScene.Logger.ErrorFormat("{0} Failed conversion of heightmap to mesh. For={1}/{2}, e={3}",
                                                LogHeader, physicsScene.RegionName, extentBase, e);
            }

            indicesCountO = indicesCount;
            indicesO = indices;
            verticesCountO = verticesCount;
            verticesO = vertices;

            return ret;
        }