Code:

//***************************************************************// Bullet/irrlicht demo by Alan Witkowski// http://www.cs.utah.edu/~witkowsk// http://code.google.com/p/irrlamb///***************************************************************#include <irrlicht.h>#include <btBulletCollisionCommon.h>#include <btBulletDynamicsCommon.h>#include <cstdlib>using namespace irr;using namespace core;using namespace scene;using namespace video;using namespace io;using namespace gui;// Functionsstatic void CreateStartScene();static void CreateBox(const btVector3 &TPosition, const vector3df &TScale, btScalar TMass);static void CreateSphere(const btVector3 &TPosition, btScalar TRadius, btScalar TMass);static void UpdatePhysics(u32 TDeltaTime);static void UpdateRender(btRigidBody *TObject);static void ClearObjects();static int GetRandInt(int TMax) { return rand() % TMax; }// Globalsstatic bool Done = false;static btDiscreteDynamicsWorld *World;static IrrlichtDevice *irrDevice;static IVideoDriver *irrDriver;static ISceneManager *irrScene;static IGUIEnvironment *irrGUI;static IFileSystem *irrFile;static ITimer *irrTimer;static ILogger *irrLog;static list<btRigidBody *> Objects;// Event receiverclass EventReceiverClass : public IEventReceiver  {public:virtual bool OnEvent(const SEvent &TEvent) {if(TEvent.EventType == EET_KEY_INPUT_EVENT && !TEvent.KeyInput.PressedDown) {switch(TEvent.KeyInput.Key) {case KEY_ESCAPE:Done = true;break;case KEY_KEY_1:CreateBox(btVector3(GetRandInt(10) - 5.0f, 7.0f, GetRandInt(10) - 5.0f), vector3df(GetRandInt(3) + 0.5f, GetRandInt(3) + 0.5f, GetRandInt(3) + 0.5f), 1.0f);break;case KEY_KEY_2:CreateSphere(btVector3(GetRandInt(10) - 5.0f, 7.0f, GetRandInt(10) - 5.0f), GetRandInt(5) / 5.0f + 0.2f, 1.0f);break;case KEY_KEY_X:CreateStartScene();break;default:return false;break;}return true;}return false;}};int main() {// Initialize irrlichtEventReceiverClass Receiver;irrDevice = createDevice(video::EDT_OPENGL, dimension2d<u32>(800, 600), 32, false, false, false, &Receiver);irrGUI = irrDevice->getGUIEnvironment();irrTimer = irrDevice->getTimer();irrScene = irrDevice->getSceneManager();irrDriver = irrDevice->getVideoDriver();irrDevice->getCursorControl()->setVisible(0);// Initialize bulletbtDefaultCollisionConfiguration *CollisionConfiguration = new btDefaultCollisionConfiguration();btBroadphaseInterface *BroadPhase = new btAxisSweep3(btVector3(-1000, -1000, -1000), btVector3(1000, 1000, 1000));btCollisionDispatcher *Dispatcher = new btCollisionDispatcher(CollisionConfiguration);btSequentialImpulseConstraintSolver *Solver = new btSequentialImpulseConstraintSolver();World = new btDiscreteDynamicsWorld(Dispatcher, BroadPhase, Solver, CollisionConfiguration);// Add cameraICameraSceneNode *Camera = irrScene->addCameraSceneNodeFPS(0, 50, 0.02);Camera->setPosition(vector3df(0, 5, -5));Camera->setTarget(vector3df(0, 0, 0));// Create textIGUISkin *Skin = irrGUI->getSkin();Skin->setColor(EGDC_BUTTON_TEXT, SColor(255, 255, 255, 255));irrGUI->addStaticText(L"Hit 1 to create a box\nHit 2 to create a sphere\nHit x to reset", rect<s32>(0, 0, 200, 100), false);// Create the initial sceneirrScene->addLightSceneNode(0, core::vector3df(2, 5, -2), SColorf(4, 4, 4, 1));CreateStartScene();// Main loopu32 TimeStamp = irrTimer->getTime(), DeltaTime = 0;while(!Done) {DeltaTime = irrTimer->getTime() - TimeStamp;TimeStamp = irrTimer->getTime();UpdatePhysics(DeltaTime);irrDriver->beginScene(true, true, SColor(255, 20, 0, 0));irrScene->drawAll();irrGUI->drawAll();irrDriver->endScene();irrDevice->run();}ClearObjects();delete World;delete Solver;delete Dispatcher;delete BroadPhase;delete CollisionConfiguration;irrDevice->drop();return 0;}// Runs the physics simulation.// - TDeltaTime tells the simulation how much time has passed since the last frame so the simulation can run independently of the frame rate.void UpdatePhysics(u32 TDeltaTime) {World->stepSimulation(TDeltaTime * 0.001f, 60);// Relay the object's orientation to irrlichtfor(list<btRigidBody *>::Iterator Iterator = Objects.begin(); Iterator != Objects.end(); ++Iterator) {UpdateRender(*Iterator);}}// Creates a base boxvoid CreateStartScene() {ClearObjects();CreateBox(btVector3(0.0f, 0.0f, 0.0f), vector3df(10.0f, 0.5f, 10.0f), 0.0f);}// Create a box rigid bodyvoid CreateBox(const btVector3 &TPosition, const vector3df &TScale, btScalar TMass) {ISceneNode *Node = irrScene->addCubeSceneNode(1.0f);Node->setScale(TScale);Node->setMaterialFlag(EMF_LIGHTING, 1);Node->setMaterialFlag(EMF_NORMALIZE_NORMALS, true);// Set the initial position of the objectbtTransform Transform;Transform.setIdentity();Transform.setOrigin(TPosition);btDefaultMotionState *MotionState = new btDefaultMotionState(Transform);// Create the shapebtVector3 HalfExtents(TScale.X * 0.5f, TScale.Y * 0.5f, TScale.Z * 0.5f);btCollisionShape *Shape = new btBoxShape(HalfExtents);// Add massbtVector3 LocalInertia;Shape->calculateLocalInertia(TMass, LocalInertia);// Create the rigid body objectbtRigidBody *RigidBody = new btRigidBody(TMass, MotionState, Shape, LocalInertia);// Store a pointer to the irrlicht node so we can update it laterRigidBody->setUserPointer((void *)(Node));// Add it to the worldWorld->addRigidBody(RigidBody);Objects.push_back(RigidBody);}// Create a sphere rigid bodyvoid CreateSphere(const btVector3 &TPosition, btScalar TRadius, btScalar TMass) {ISceneNode *Node = irrScene->addSphereSceneNode(TRadius, 32);Node->setMaterialFlag(EMF_LIGHTING, 1);Node->setMaterialFlag(EMF_NORMALIZE_NORMALS, true);// Set the initial position of the objectbtTransform Transform;Transform.setIdentity();Transform.setOrigin(TPosition);btDefaultMotionState *MotionState = new btDefaultMotionState(Transform);// Create the shapebtCollisionShape *Shape = new btSphereShape(TRadius);// Add massbtVector3 LocalInertia;Shape->calculateLocalInertia(TMass, LocalInertia);// Create the rigid body objectbtRigidBody *RigidBody = new btRigidBody(TMass, MotionState, Shape, LocalInertia);// Store a pointer to the irrlicht node so we can update it laterRigidBody->setUserPointer((void *)(Node));// Add it to the worldWorld->addRigidBody(RigidBody);Objects.push_back(RigidBody);}// Passes bullet's orientation to irrlichtvoid UpdateRender(btRigidBody *TObject) {ISceneNode *Node = static_cast<ISceneNode *>(TObject->getUserPointer());// Set positionbtVector3 Point = TObject->getCenterOfMassPosition();Node->setPosition(vector3df((f32)Point[0], (f32)Point[1], (f32)Point[2]));// Set rotationvector3df Euler;const btQuaternion& TQuat = TObject->getOrientation();quaternion q(TQuat.getX(), TQuat.getY(), TQuat.getZ(), TQuat.getW());q.toEuler(Euler);Euler *= RADTODEG;Node->setRotation(Euler);}// Removes all objects from the worldvoid ClearObjects() {for(list<btRigidBody *>::Iterator Iterator = Objects.begin(); Iterator != Objects.end(); ++Iterator) {btRigidBody *Object = *Iterator;// Delete irrlicht nodeISceneNode *Node = static_cast<ISceneNode *>(Object->getUserPointer());Node->remove();// Remove the object from the worldWorld->removeRigidBody(Object);// Free memorydelete Object->getMotionState();delete Object->getCollisionShape();delete Object;}Objects.clear();}