Code:

#include <irrlicht.h> #include <btBulletDynamicsCommon.h> class MotionState : public btMotionState { public:    MotionState(const btTransform& initalTransformation, irr::scene::ISceneNode* const node) :       node(node), initalTransformation(initalTransformation)    {    }    void getWorldTransform(btTransform& worldTrans) const    {       worldTrans = this->initalTransformation;    }    void setWorldTransform(const btTransform& worldTrans)    {       worldTrans.getOpenGLMatrix(matr.pointer());       this->node->setRotation(matr.getRotationDegrees());       this->node->setPosition(matr.getTranslation());    } private:    irr::scene::ISceneNode* const node;    irr::core::matrix4 matr;    btTransform initalTransformation; }; int main() {    irr::IrrlichtDevice* device = irr::createDevice();    irr::video::IVideoDriver* driver = device->getVideoDriver();    irr::scene::ISceneManager* smgr = device->getSceneManager();    btDbvtBroadphase* broadphase = new btDbvtBroadphase;    btDefaultCollisionConfiguration* collisionConfiguration = new btDefaultCollisionConfiguration;    btCollisionDispatcher* dispatcher = new btCollisionDispatcher(collisionConfiguration);    btSequentialImpulseConstraintSolver* solver = new btSequentialImpulseConstraintSolver;    btDiscreteDynamicsWorld* dynamicsWorld = new btDiscreteDynamicsWorld(dispatcher, broadphase, solver, collisionConfiguration);    dynamicsWorld->setGravity(btVector3(0, -9.80665, 0));    irr::scene::ICameraSceneNode* camera = smgr->addCameraSceneNode();    camera->setPosition(irr::core::vector3df(0.0f, 5.0f, -15.0f));    btCollisionShape* groundShape = new btStaticPlaneShape(btVector3(0.0, 1.0, 0.0), 1.0);    btDefaultMotionState* groundMotionState = new btDefaultMotionState(btTransform(btQuaternion(0, 0, 0, 1),btVector3(0,-1,0)));    btRigidBody::btRigidBodyConstructionInfo groundRigidBodyCI(0,groundMotionState,groundShape,btVector3(0.0, 0.0, 0.0));    btRigidBody* groundRigidBody = new btRigidBody(groundRigidBodyCI);    dynamicsWorld->addRigidBody(groundRigidBody);    irr::scene::IMeshSceneNode* sphere = smgr->addSphereSceneNode(1.0f);    sphere->setMaterialFlag(irr::video::EMF_LIGHTING, false);    btCollisionShape* fallShape = new btSphereShape(1.0);    MotionState* fallMotionState = new MotionState(btTransform(btQuaternion(0.0, 0.0, 0.0, 1.0), btVector3(0.0, 50.0, 0.0)), sphere);    btScalar mass = 1.0;    btVector3 inertia(0.0, 0.0, 0.0);    fallShape->calculateLocalInertia(mass, inertia);    btRigidBody::btRigidBodyConstructionInfo fallRigidBodyCI(mass, fallMotionState, fallShape, inertia);    btRigidBody* fallRigidBody = new btRigidBody(fallRigidBodyCI);    dynamicsWorld->addRigidBody(fallRigidBody);    irr::ITimer* const timer = device->getTimer();    irr::u32 then = timer->getTime();    while (device->run())    {       const irr::u32 now = timer->getTime();       const btScalar frameDeltaTime = (btScalar)(now - then)*0.001; // Time in seconds       then = now;       dynamicsWorld->stepSimulation(frameDeltaTime, 10);       driver->beginScene(true, true, irr::video::SColor(255, 133, 133, 133));       smgr->drawAll();       driver->endScene();    }    // Clean up behind ourselves like good little programmers    dynamicsWorld->removeRigidBody(fallRigidBody);    delete fallRigidBody->getMotionState();    delete fallRigidBody;    dynamicsWorld->removeRigidBody(groundRigidBody);    delete groundRigidBody->getMotionState();    delete groundRigidBody;    delete fallShape;    delete groundShape;    delete dynamicsWorld;    delete solver;    delete dispatcher;    delete collisionConfiguration;    delete broadphase;    device->drop();    return 0; } }