#include <iostream>
#include <btBulletDynamicsCommon.h>

int main(int argc, char *argv[])
{
    btBroadphaseInterface * broadphase = new btDbvtBroadphase();
    btDefaultCollisionConfiguration * collision_configuration = new btDefaultCollisionConfiguration();
    btCollisionDispatcher * dispatcher = new btCollisionDispatcher(collision_configuration);
    btSequentialImpulseConstraintSolver * solver = new btSequentialImpulseConstraintSolver;
    btDiscreteDynamicsWorld * dynamics_world = new btDiscreteDynamicsWorld(dispatcher, broadphase, solver, collision_configuration);
    dynamics_world->setGravity(btVector3(0, -9.8, 0));

    btCollisionShape * ground_shape = new btStaticPlaneShape(btVector3(0, 1, 0), 1);
    btCollisionShape * fall_shape = new btSphereShape(1);

    btDefaultMotionState * ground_motion_state =
        new btDefaultMotionState(btTransform(btQuaternion(0, 0, 0, 1), btVector3(0, -1, 0)));
    btRigidBody::btRigidBodyConstructionInfo
        ground_rigid_body_ci(0, ground_motion_state, ground_shape, btVector3(0, 0, 0));
    btRigidBody * ground_rigid_body = new btRigidBody(ground_rigid_body_ci);

    dynamics_world->addRigidBody(ground_rigid_body);

    btDefaultMotionState * fall_motion_state =
        new btDefaultMotionState(btTransform(btQuaternion(0, 0, 0, 1), btVector3(0, 50, 0)));

    btScalar mass = 1;
    btVector3 fall_inertia(0, 0, 0);
    fall_shape->calculateLocalInertia(mass, fall_inertia);
    btRigidBody::btRigidBodyConstructionInfo
        fall_rigid_body_ci(mass, fall_motion_state, fall_shape, fall_inertia);
    btRigidBody * fall_rigid_body = new btRigidBody(fall_rigid_body_ci);

    dynamics_world->addRigidBody(fall_rigid_body);

    for (int i = 0; i < 300; i++)
    {
        dynamics_world->stepSimulation(1.0 / 60.0, 10);

        btTransform trans;
        fall_rigid_body->getMotionState()->getWorldTransform(trans);

        std::cout << "sphere height: " << trans.getOrigin().getY() << std::endl;
    }

    delete fall_rigid_body;
    delete fall_motion_state;

    delete ground_rigid_body;
    delete ground_motion_state;

    delete fall_shape;
    delete ground_shape;

    delete dynamics_world;
    delete solver;
    delete dispatcher;
    delete collision_configuration;
    delete broadphase;

    return 0;
}