Code:

btCollisionShape* boxShape = new btBoxShape(btVector3((M.x-m.x)*0.5f, (M.y-m.y)*0.5f, (M.z-m.z)*0.5f)); //need to give btVector3 of halfExtentsboxShape->setMargin(gCollisionMargin);s = mObjMgr->ObjInstances[i]->Scale;boxShape->setLocalScaling(btVector3(s, s, s));btRigidBody* BTWorld::LocalCreateRigidBody(float mass, const btTransform& startTransform, btCollisionShape* shape){//rigidbody is dynamic if and only if mass is non zero, otherwise staticbool isDynamic = (mass != 0.f);btVector3 localInertia(0,0,0);if (isDynamic)shape->calculateLocalInertia(mass,localInertia);//using motionstate is recommended, it provides interpolation capabilities, and only synchronizes 'active' objects//btMotionState allows the dynamics world to synchronize the updated world transforms with graphics objects//#define USE_MOTIONSTATE 1//#ifdef USE_MOTIONSTATEbtDefaultMotionState* myMotionState = new btDefaultMotionState(startTransform);myMotionState->setWorldTransform(startTransform);btRigidBody* body = new btRigidBody(mass,myMotionState,shape,localInertia);body->setCenterOfMassTransform(startTransform);//#else//btRigidBody* body = new btRigidBody(mass,startTransform,shape,localInertia);//#endifassert(mDynamicsWorld);assert(body);mDynamicsWorld->addRigidBody(body);return body;}