Physics Simulation Forum

#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;
}
}