// Create terrain mesh from a heightmap.
        public BSTerrainMesh(BSScene physicsScene, Vector3 regionBase, uint id, float[] initialMap,
            Vector3 minCoords, Vector3 maxCoords)
            : base(physicsScene, regionBase, id)
        {
            int indicesCount;
            int[] indices;
            int verticesCount;
            float[] vertices;

            m_savedHeightMap = initialMap;

            m_sizeX = (int)(maxCoords.X - minCoords.X);
            m_sizeY = (int)(maxCoords.Y - minCoords.Y);

            bool meshCreationSuccess = false;
            if (BSParam.TerrainMeshMagnification == 1)
            {
                // If a magnification of one, use the old routine that is tried and true.
                meshCreationSuccess = BSTerrainMesh.ConvertHeightmapToMesh(PhysicsScene,
                    initialMap, m_sizeX, m_sizeY, // input size
                    Vector3.Zero, // base for mesh
                    out indicesCount, out indices, out verticesCount, out vertices);
            }
            else
            {
                // Other magnifications use the newer routine
                meshCreationSuccess = BSTerrainMesh.ConvertHeightmapToMesh2(PhysicsScene,
                    initialMap, m_sizeX, m_sizeY, // input size
                    BSParam.TerrainMeshMagnification,
                    physicsScene.TerrainManager.WorldMax,
                    Vector3.Zero, // base for mesh
                    out indicesCount, out indices, out verticesCount, out vertices);
            }
            if (!meshCreationSuccess)
            {
                // DISASTER!!
                PhysicsScene.DetailLog("{0},BSTerrainMesh.create,failedConversionOfHeightmap,id={1}",
                    BSScene.DetailLogZero, ID);
                PhysicsScene.Logger.ErrorFormat("{0} Failed conversion of heightmap to mesh! base={1}", LogHeader,
                    TerrainBase);
                // Something is very messed up and a crash is in our future.
                return;
            }

            PhysicsScene.DetailLog("{0},BSTerrainMesh.create,meshid,id={1},indices={2},indSz={3},vertices={4},vertSz={5}",
                BSScene.DetailLogZero, ID, indicesCount, indices.Length, verticesCount, vertices.Length);

            m_terrainShape = PhysicsScene.PE.CreateMeshShape(PhysicsScene.World, indicesCount, indices, verticesCount,
                vertices);

            if (!m_terrainShape.HasPhysicalShape)
            {
                // DISASTER!!
                PhysicsScene.DetailLog("{0},BSTerrainMesh.create,failedCreationOfShape,id={1}", BSScene.DetailLogZero,
                    ID);
                PhysicsScene.Logger.ErrorFormat("{0} Failed creation of terrain mesh! base={1}", LogHeader, TerrainBase);
                // Something is very messed up and a crash is in our future.
                return;
            }

            Vector3 pos = regionBase;
            Quaternion rot = Quaternion.Identity;

            m_terrainBody = PhysicsScene.PE.CreateBodyWithDefaultMotionState(m_terrainShape, ID, pos, rot);
            if (!m_terrainBody.HasPhysicalBody)
            {
                // DISASTER!!
                PhysicsScene.Logger.ErrorFormat("{0} Failed creation of terrain body! base={1}", LogHeader, TerrainBase);
                // Something is very messed up and a crash is in our future.
                return;
            }

            physicsScene.PE.SetShapeCollisionMargin(m_terrainShape, BSParam.TerrainCollisionMargin);

            // Set current terrain attributes
            PhysicsScene.PE.SetFriction(m_terrainBody, BSParam.TerrainFriction);
            PhysicsScene.PE.SetHitFraction(m_terrainBody, BSParam.TerrainHitFraction);
            PhysicsScene.PE.SetRestitution(m_terrainBody, BSParam.TerrainRestitution);
            PhysicsScene.PE.SetContactProcessingThreshold(m_terrainBody, BSParam.TerrainContactProcessingThreshold);
            PhysicsScene.PE.SetCollisionFlags(m_terrainBody, CollisionFlags.CF_STATIC_OBJECT);

            // Static objects are not very massive.
            PhysicsScene.PE.SetMassProps(m_terrainBody, 0f, Vector3.Zero);

            // Put the new terrain to the world of physical objects
            PhysicsScene.PE.AddObjectToWorld(PhysicsScene.World, m_terrainBody);

            // Redo its bounding box now that it is in the world
            PhysicsScene.PE.UpdateSingleAabb(PhysicsScene.World, m_terrainBody);

            m_terrainBody.collisionType = CollisionType.Terrain;
            m_terrainBody.ApplyCollisionMask(PhysicsScene);

            if (BSParam.UseSingleSidedMeshes)
            {
                PhysicsScene.DetailLog("{0},BSTerrainMesh.settingCustomMaterial,id={1}", BSScene.DetailLogZero, id);
                PhysicsScene.PE.AddToCollisionFlags(m_terrainBody, CollisionFlags.CF_CUSTOM_MATERIAL_CALLBACK);
            }

            // Make it so the terrain will not move or be considered for movement.
            PhysicsScene.PE.ForceActivationState(m_terrainBody, ActivationState.DISABLE_SIMULATION);
        }
        public override bool AddObjectToWorld(BulletWorld pWorld, BulletBody pBody)
        {
            DiscreteDynamicsWorld world = (pWorld as BulletWorldXNA).world;
            CollisionObject cbody = (pBody as BulletBodyXNA).body;
            RigidBody rbody = cbody as RigidBody;

            // Bullet resets several variables when an object is added to the world. In particular,
            //   BulletXNA resets position and rotation. Gravity is also reset depending on the static/dynamic
            //   type. Of course, the collision flags in the broadphase proxy are initialized to default.
            IndexedMatrix origPos = cbody.GetWorldTransform();
            if (rbody != null)
            {
                IndexedVector3 origGrav = rbody.GetGravity();
                world.AddRigidBody(rbody);
                rbody.SetGravity(origGrav);
            }
            else
            {
                world.AddCollisionObject(cbody);
            }
            cbody.SetWorldTransform(origPos);

            pBody.ApplyCollisionMask(pWorld.physicsScene);

            //if (body.GetBroadphaseHandle() != null)
            //    world.UpdateSingleAabb(body);
            return true;
        }
        // Create the initial instance of terrain and the underlying ground plane.
        // This is called from the initialization routine so we presume it is
        //    safe to call Bullet in real time. We hope no one is moving prims around yet.
        public void CreateInitialGroundPlaneAndTerrain()
        {
            DetailLog("{0},BSTerrainManager.CreateInitialGroundPlaneAndTerrain,region={1}", BSScene.DetailLogZero,
                PhysicsScene.RegionName);
            // The ground plane is here to catch things that are trying to drop to negative infinity
            BulletShape groundPlaneShape = PhysicsScene.PE.CreateGroundPlaneShape(BSScene.GROUNDPLANE_ID, 1f,
                BSParam.TerrainCollisionMargin);
            m_groundPlane = PhysicsScene.PE.CreateBodyWithDefaultMotionState(groundPlaneShape,
                BSScene.GROUNDPLANE_ID, Vector3.Zero, Quaternion.Identity);

            PhysicsScene.PE.AddObjectToWorld(PhysicsScene.World, m_groundPlane);
            PhysicsScene.PE.UpdateSingleAabb(PhysicsScene.World, m_groundPlane);
            // Ground plane does not move
            PhysicsScene.PE.ForceActivationState(m_groundPlane, ActivationState.DISABLE_SIMULATION);
            // Everything collides with the ground plane.
            m_groundPlane.collisionType = CollisionType.Groundplane;
            m_groundPlane.ApplyCollisionMask(PhysicsScene);

            m_terrain = new BSTerrainHeightmap(PhysicsScene, Vector3.Zero, BSScene.TERRAIN_ID, m_worldMax);
        }
        // =====================================================================================
        // btDynamicsWorld entries
        public override bool AddObjectToWorld(BulletWorld world, BulletBody obj)
        {
            BulletWorldUnman worldu = world as BulletWorldUnman;
            BulletBodyUnman bodyu = obj as BulletBodyUnman;

            // Bullet resets several variables when an object is added to the world.
            //   Gravity is reset to world default depending on the static/dynamic
            //   type. Of course, the collision flags in the broadphase proxy are initialized to default.
            Vector3 origGrav = BSAPICPP.GetGravity2(bodyu.ptr);

            bool ret = BSAPICPP.AddObjectToWorld2(worldu.ptr, bodyu.ptr);

            if (ret)
            {
                BSAPICPP.SetGravity2(bodyu.ptr, origGrav);
                obj.ApplyCollisionMask(world.physicsScene);
            }
            return ret;
        }