TEST_F(BodyTest, RotatingSerializationSuccess) {
EXPECT_FALSE(rotating_body_.is_massless());
EXPECT_FALSE(rotating_body_.is_oblate());
serialization::Body message;
RotatingBody<World> const* cast_rotating_body;
rotating_body_.WriteToMessage(&message);
EXPECT_TRUE(message.has_massive_body());
EXPECT_FALSE(message.has_massless_body());
EXPECT_TRUE(message.massive_body().HasExtension(
serialization::RotatingBody::rotating_body));
EXPECT_EQ(17, message.massive_body().gravitational_parameter().magnitude());
serialization::RotatingBody const rotating_body_extension =
message.massive_body().GetExtension(
serialization::RotatingBody::rotating_body);
EXPECT_EQ(3, rotating_body_extension.reference_angle().magnitude());
EXPECT_EQ(4,
rotating_body_extension.reference_instant().scalar().magnitude());
EXPECT_EQ(angular_velocity_,
AngularVelocity<World>::ReadFromMessage(
rotating_body_extension.angular_velocity()));
// Dispatching from |MassiveBody|.
not_null<std::unique_ptr<MassiveBody const>> const massive_body =
MassiveBody::ReadFromMessage(message);
EXPECT_EQ(rotating_body_.gravitational_parameter(),
massive_body->gravitational_parameter());
cast_rotating_body = dynamic_cast<RotatingBody<World> const*>(&*massive_body);
EXPECT_THAT(cast_rotating_body, NotNull());
EXPECT_EQ(rotating_body_.gravitational_parameter(),
cast_rotating_body->gravitational_parameter());
EXPECT_EQ(rotating_body_.angular_velocity(),
cast_rotating_body->angular_velocity());
EXPECT_EQ(rotating_body_.AngleAt(Instant()),
cast_rotating_body->AngleAt(Instant()));
// Dispatching from |Body|.
not_null<std::unique_ptr<Body const>> const body =
Body::ReadFromMessage(message);
cast_rotating_body = dynamic_cast<RotatingBody<World> const*>(&*body);
EXPECT_THAT(cast_rotating_body, NotNull());
EXPECT_EQ(rotating_body_.gravitational_parameter(),
cast_rotating_body->gravitational_parameter());
EXPECT_EQ(rotating_body_.angular_velocity(),
cast_rotating_body->angular_velocity());
EXPECT_EQ(rotating_body_.AngleAt(Instant()),
cast_rotating_body->AngleAt(Instant()));
}
void TestRotatingBody() {
using F = Frame<Tag, tag, true>;
AngularVelocity<F> const angular_velocity =
AngularVelocity<F>({-1 * Radian / Second,
2 * Radian / Second,
5 * Radian / Second});
auto const rotating_body =
RotatingBody<F>(17 * SIUnit<GravitationalParameter>(),
typename RotatingBody<F>::Parameters(
3 * Radian,
Instant() + 4 * Second,
angular_velocity));
serialization::Body message;
RotatingBody<F> const* cast_rotating_body;
rotating_body.WriteToMessage(&message);
EXPECT_TRUE(message.has_massive_body());
EXPECT_FALSE(message.has_massless_body());
EXPECT_TRUE(message.massive_body().HasExtension(
serialization::RotatingBody::rotating_body));
not_null<std::unique_ptr<MassiveBody const>> const massive_body =
MassiveBody::ReadFromMessage(message);
EXPECT_EQ(rotating_body.gravitational_parameter(),
massive_body->gravitational_parameter());
cast_rotating_body = dynamic_cast<RotatingBody<F> const*>(&*massive_body);
EXPECT_THAT(cast_rotating_body, NotNull());
}
TEST_F(ManœuvreTest, TargetΔv) {
Instant const t0 = Instant();
Vector<double, World> e_y({0, 1, 0});
Manœuvre<World> manœuvre(1 * Newton /*thrust*/,
2 * Kilogram /*initial_mass*/,
1 * Newton * Second / Kilogram /*specific_impulse*/,
e_y /*direction*/);
EXPECT_EQ(1 * Newton, manœuvre.thrust());
EXPECT_EQ(2 * Kilogram, manœuvre.initial_mass());
EXPECT_EQ(1 * Metre / Second, manœuvre.specific_impulse());
EXPECT_EQ(e_y, manœuvre.direction());
EXPECT_EQ(1 * Kilogram / Second, manœuvre.mass_flow());
manœuvre.set_Δv(1 * Metre / Second);
EXPECT_EQ(1 * Metre / Second, manœuvre.Δv());
EXPECT_EQ((2 - 2 / e) * Second, manœuvre.duration());
EXPECT_EQ((2 - 2 / Sqrt(e)) * Second, manœuvre.time_to_half_Δv());
EXPECT_EQ((2 / e) * Kilogram, manœuvre.final_mass());
manœuvre.set_time_of_half_Δv(t0);
EXPECT_EQ(t0 - (2 - 2 / Sqrt(e)) * Second, manœuvre.initial_time());
EXPECT_EQ(t0 + (2 / Sqrt(e) - 2 / e) * Second, manœuvre.final_time());
EXPECT_EQ(t0, manœuvre.time_of_half_Δv());
EXPECT_EQ(
0 * Metre / Pow<2>(Second),
manœuvre.acceleration()(manœuvre.initial_time() - 1 * Second).Norm());
EXPECT_EQ(0.5 * Metre / Pow<2>(Second),
manœuvre.acceleration()(manœuvre.initial_time()).Norm());
EXPECT_EQ(Sqrt(e) / 2 * Metre / Pow<2>(Second),
manœuvre.acceleration()(manœuvre.time_of_half_Δv()).Norm());
EXPECT_EQ((e / 2) * Metre / Pow<2>(Second),
manœuvre.acceleration()(manœuvre.final_time()).Norm());
EXPECT_EQ(0 * Metre / Pow<2>(Second),
manœuvre.acceleration()(manœuvre.final_time() + 1 * Second).Norm());
}
std::unique_ptr<MassiveBody> SolarSystem<Frame>::MakeMassiveBody(
serialization::GravityModel::Body const& body) {
CHECK(body.has_gravitational_parameter());
CHECK_EQ(body.has_j2(), body.has_reference_radius());
CHECK_EQ(body.has_axis_declination(), body.has_axis_right_ascension());
MassiveBody::Parameters massive_body_parameters(
ParseQuantity<GravitationalParameter>(
body.gravitational_parameter()));
if (body.has_axis_declination()) {
// TODO(phl): Parse the additional parameters.
typename RotatingBody<Frame>::Parameters
rotating_body_parameters(
0 * Radian,
Instant(),
Bivector<double, Frame>(
RadiusLatitudeLongitude(
1.0,
ParseQuantity<Angle>(body.axis_declination()),
ParseQuantity<Angle>(body.axis_right_ascension())).
ToCartesian()) * Radian / Second);
if (body.has_j2()) {
typename OblateBody<Frame>::Parameters oblate_body_parameters(
ParseQuantity<double>(body.j2()),
ParseQuantity<Length>(body.reference_radius()));
return std::make_unique<OblateBody<Frame>>(massive_body_parameters,
rotating_body_parameters,
oblate_body_parameters);
} else {
return std::make_unique<RotatingBody<Frame>>(massive_body_parameters,
rotating_body_parameters);
}
} else {
return std::make_unique<MassiveBody>(massive_body_parameters);
}
}
double principia__IteratorGetTime(Iterator const* const iterator) {
journal::Method<journal::IteratorGetTime> m({iterator});
CHECK_NOTNULL(iterator);
auto const typed_iterator = check_not_null(
dynamic_cast<TypedIterator<DiscreteTrajectory<World>> const*>(iterator));
return m.Return(typed_iterator->Get<double>(
[](DiscreteTrajectory<World>::Iterator const& iterator) -> double {
return (iterator.time() - Instant()) / Second;
}));
}
Plugin* NewPlugin(double const initial_time,
int const sun_index,
double const sun_gravitational_parameter,
double const planetarium_rotation_in_degrees) {
LOG(INFO) << "Constructing Principia plugin";
std::unique_ptr<Plugin> result = std::make_unique<Plugin>(
Instant(initial_time * Second),
sun_index,
sun_gravitational_parameter * SIUnit<GravitationalParameter>(),
planetarium_rotation_in_degrees * Degree);
LOG(INFO) << "Plugin constructed";
return result.release();
}
void Ephemeris<Frame>::AppendMassiveBodiesState(
typename NewtonianMotionEquation::SystemState const& state) {
last_state_ = state;
int index = 0;
for (auto& trajectory : trajectories_) {
trajectory->Append(
state.time.value,
DegreesOfFreedom<Frame>(state.positions[index].value,
state.velocities[index].value));
++index;
}
// Record an intermediate state if we haven't done so for too long.
CHECK(!trajectories_.empty());
Instant const t_last_intermediate_state =
checkpoints_.empty()
? Instant() - std::numeric_limits<double>::infinity() * Second
: checkpoints_.back().system_state.time.value;
if (t_max() - t_last_intermediate_state > max_time_between_checkpoints) {
checkpoints_.push_back(GetCheckpoint());
}
}
void AdvanceTime(Plugin* const plugin,
double const t,
double const planetarium_rotation) {
CHECK_NOTNULL(plugin)->AdvanceTime(Instant(t * Second),
planetarium_rotation * Degree);
}
MockPlugin::MockPlugin()
: Plugin(Instant(),
Angle()) {}
TEST_F(SolarSystemTest, RealSolarSystem) {
solar_system_.Initialize(
SOLUTION_DIR / "astronomy" / "gravity_model.proto.txt",
SOLUTION_DIR / "astronomy" /
"initial_state_jd_2433282_500000000.proto.txt");
EXPECT_EQ(Instant() - 50 * 365.25 * Day, solar_system_.epoch());
EXPECT_THAT(solar_system_.names(),
ElementsAreArray({"Ariel",
"Callisto",
"Ceres",
"Charon",
"Deimos",
"Dione",
"Earth",
"Enceladus",
"Eris",
"Europa",
"Ganymede",
"Iapetus",
"Io",
"Jupiter",
"Mars",
"Mercury",
"Mimas",
"Miranda",
"Moon",
"Neptune",
"Oberon",
"Phobos",
"Pluto",
"Rhea",
"Saturn",
"Sun",
"Tethys",
"Titan",
"Titania",
"Triton",
"Umbriel",
"Uranus",
"Venus",
"Vesta"}));
EXPECT_EQ(1, solar_system_.index("Callisto"));
EXPECT_EQ(32, solar_system_.index("Venus"));
auto const ephemeris = solar_system_.MakeEphemeris(
/*fitting_tolerance=*/1 * Metre,
Ephemeris<ICRFJ2000Equator>::FixedStepParameters(
integrators::McLachlanAtela1992Order4Optimal<
Position<ICRFJ2000Equator>>(),
/*step=*/1 * Second));
auto const earth = solar_system_.massive_body(*ephemeris, "Earth");
EXPECT_LT(RelativeError(5.97258 * Yotta(Kilogram), earth->mass()), 6E-9);
auto const& earth_trajectory = solar_system_.trajectory(*ephemeris, "Earth");
EXPECT_TRUE(earth_trajectory.empty());
auto const& sun_initial_state = solar_system_.initial_state_message("Sun");
EXPECT_EQ("+1.309126697236264E+05 km", sun_initial_state.x());
EXPECT_EQ("-7.799754996220354E-03 km/s", sun_initial_state.vx());
auto const& sun_gravity_model = solar_system_.gravity_model_message("Sun");
EXPECT_EQ("286.13 deg", sun_gravity_model.axis_right_ascension());
EXPECT_EQ("63.87 deg", sun_gravity_model.axis_declination());
}