def check_margins(trojan1: CelestialBody, trojan2: CelestialBody,\
central: CelestialBody, margin: float) -> bool:
"""
Checks to see if two planets in a Trojan pair are within a given percent
margin of a 1:1 period resonance.
Parameters
----------
- trojan1 (CelestialBody): One member of the co-orbital pair.
- trojan2 (CelestialBody): The other member of the co-orbital pair.
- central (CelestialBody): The central body in the system.
- margin (float): The allowed percent deviation from a 1:1 period resonance.
Returns
-------
- in_margin (bool): True if within the margin, false if not.
"""
# Get the orbital periods of each planet.
P1 = trojan1.period(central)
P2 = trojan2.period(central)
# Compute the percent difference between the periods.
diff = abs(P1 - P2)
avg = np.average([P1, P2])
p_diff = (diff / avg) * 100
# Will return true if the percent difference exceeds the margin.
return not (p_diff > margin)
def test_ShouldMoveThreeBodiesOfEqualMassTowardsCenterOfMass(self):
body1 = CelestialBody("N",6e24,Vector(0,10e10,0),self.zero,self.zero)
body2 = CelestialBody("M",6e24,Vector(-6e10,-8e10,0),self.zero,self.zero)
body3 = CelestialBody("L",6e24,Vector(6e10,-8e10,0),self.zero,self.zero)
system = System("Tri-body", [body1,body2,body3])
system.update(1)
self.assertTrue(Vector.sumOfVectors([body1.velocity, body2.velocity,body3.velocity]) == Vector(0,0,0))
self.assertTrue(Vector.absolute(body1.position) == Vector.absolute(body2.position))
self.assertTrue(Vector.absolute(body1.position) == Vector.absolute(body3.position))
def test_ShouldAccelerateASmallBodyWithSmallStartingVelocityTowardsABigOne(self):
body1 = CelestialBody("N",6e24,Vector(0,0,0),self.zero,self.zero)
body2 = CelestialBody("M",1e3,Vector(1e7,0,0),Vector(0,1000,0),self.zero)
system = System("Dual Body", [body1,body2])
distance = 1e7
for _ in range(1,101):
system.update(1)
new_distance = CelestialBody.calcDistance(body1,body2)
self.assertTrue(new_distance < distance)
distance = new_distance
def test_ShouldAllowEscapeOfSmallBodyWithHighVelocity(self):
body1 = CelestialBody("N",6e24,Vector(0,0,0),self.zero,self.zero)
body2 = CelestialBody("M",1e3,Vector(1e7,0,0),Vector(0,3e8,0),self.zero)
system = System("Dual Body", [body1,body2])
distance = 1e7
for _ in range(1,101):
system.update(1)
new_distance = CelestialBody.calcDistance(body1,body2)
self.assertTrue(new_distance > distance)
distance = new_distance
def test_ShouldGiveSameOutputNoMatterTheTickFrequency(self):
body = CelestialBody("Sun", 1E26, self.nonZero, self.nonZero2,
self.nonZero3)
for _ in range(1, 11):
body.update(0.1)
print(body.position)
print(body.velocity)
self.assertAlmostEqual(body.position, Vector(14.5, 9.5, 8.5))
self.assertAlmostEqual(body.velocity, Vector(15, 10, 5))
def test_ShouldMoveTwoStationaryBodiesDirectlyTowardsEachOther(self):
body1 = CelestialBody("N",1e25,Vector(-100,0,0),self.zero,self.zero)
body2 = CelestialBody("M",1e25,Vector(100,0,0),self.zero,self.zero)
system = System("Dual Body", [body1,body2])
system.update(10)
self.assertTrue(body1.velocity == Vector.mult(-1,body2.velocity))
self.assertTrue(body1.velocity != body2.velocity)
self.assertTrue(Vector.add(body1.velocity,body2.velocity) == self.zero)
self.assertTrue(Vector.add(body1.position,body2.position) == self.zero)
self.assertTrue(body1.position.y == body2.position.y)
self.assertTrue(body1.position.z == body2.position.z)
self.assertTrue(body1.position.y == 0)
self.assertTrue(body1.position.z == 0)
def test_ShouldConserveMomentum(self):
body1 = CelestialBody("N", 6e24, Vector(0, 10e10, 0), Vector(3,6,9), self.zero)
body2 = CelestialBody("M", 6e24, Vector(-6e10, -8e10, 0), Vector(5,12,3), self.zero)
body3 = CelestialBody("L", 6e24, Vector(6e10, -8e10, 0), Vector(9,2,19), self.zero)
bodies = [body1,body2,body3]
system = System("Tri-body", bodies)
totalMomentumBefore = Vector(0,0,0)
for body in bodies:
totalMomentumBefore = Vector.add(totalMomentumBefore, body.calcMomentum())
system.update(600)
totalMomentumAfter = Vector(0,0,0)
for body in bodies:
totalMomentumAfter = Vector.add(totalMomentumAfter, body.calcMomentum())
self.assertTrue(totalMomentumBefore == totalMomentumAfter)
def test_ShouldMoveAtConstantVelocitySingleMovingBody(self):
body = CelestialBody("N", 1e25, self.zero, Vector(10, 15, 50),
self.zero)
system = System("Single Body", [body])
system.update(10)
self.assertTrue(body.velocity == Vector(10, 15, 50))
self.assertTrue(body.position == Vector(100, 150, 500))
def __init__(self, dat_name, time_step=20000, satelite=False):
self.t = time_step
self.time = 0
self.energies = ([], [])
with open(dat_name + '.json') as json_dat:
dat = json.load(json_dat)
self.bodies = [CelestialBody(*[body] + dat[body]) for body in dat]
self.sat_target = self.bodies[4]
self.sat_reached = 0
self.sat_time = 0
for body in self.bodies:
body.update_acc(self.bodies, first=True)
def test_ShouldAccelerateASmallBodyTowardsABigOne(self):
body1 = CelestialBody("N",1e30,Vector(-100,0,0),self.zero,self.zero)
body2 = CelestialBody("M",1e23,Vector(100,0,0),self.zero,self.zero)
system = System("Dual Body", [body1,body2])
system.update(10)
self.assertTrue(body1.calcSpeed() - body2.calcSpeed() < 0)
self.assertTrue(body1.position.x + body2.position.x < 0)
self.assertTrue(body1.position.y == body2.position.y)
self.assertTrue(body1.position.z == body2.position.z)
self.assertTrue(body1.position.y == 0)
self.assertTrue(body1.position.z == 0)
def parse_line(line: str) -> CelestialBody:
"""
Parses a single line of text to produce a CelestialBody object.
Parameter
---------
- line (string): A line of text containing the information necessary to
construct a CelestialBody object.
Returns
-------
- body (CelestialBody): The CelestialBody object constructed from the
parameters given by the input line.
"""
params: List[str] = line.split(" ")
# Variables used to construct the CelestialBody object.
body_type: CelestialType = -1
body_is_trojan: bool = False
body_name: str = ""
body_mass: float = 0.0
body_radius: float = 0.0
body_position: np.array = np.zeros(3)
body_velocity: np.array = np.zeros(3)
# The parsing function cannot detect missing parameters.
for i, param in enumerate(params):
if i == 0:
# Each line should start by specifying the body type.
if params[0] == "STAR":
body_type = CelestialType.STAR
elif params[0] == "GIANT":
body_type = CelestialType.GIANT
elif params[0] == "TERRESTRIAL":
body_type = CelestialType.TERRESTRIAL
else:
raise Exception("Each line must start with a valid object type"\
+ " specification.")
else:
tokens = param.split("=")
if tokens[0] == "trojan":
body_is_trojan = tokens[1] == "True"
elif tokens[0] == "name":
body_name = tokens[1]
elif tokens[0] == "mass":
body_mass = float(tokens[1])
elif tokens[0] == "radius":
body_radius = float(tokens[1])
elif tokens[0] == "position":
vals = tokens[1].split(",")
if len(vals) != 3:
raise Exception("Position must be specified by three"\
+ " comma-separated floats")
body_position = np.array([float(vals[0]), float(vals[1]),\
float(vals[2])])
elif tokens[0] == "velocity":
vals = tokens[1].split(",")
if len(vals) != 3:
raise Exception("Velocity must be specified by three"\
+ " comma-separated floats")
body_velocity = np.array([float(vals[0]), float(vals[1]),\
float(vals[2])])
else:
raise Exception("Invalid token detected while parsing input"\
+ " file.")
body = CelestialBody(type=body_type, trojan=body_is_trojan, name=body_name,\
mass=body_mass, radius=body_radius, position=body_position,\
velocity=body_velocity)
return body
def test_ShouldNeverMoveSingleStationaryBody(self):
body = CelestialBody("N",1e25,Vector(4,7,9),self.zero,self.zero)
system = System("Single Body", [body])
system.update(10000)
self.assertTrue(body.position == Vector(4,7,9))
def test_ShouldReturnKineticEnergyWhenGivenMassAndVelocity(self):
body = CelestialBody("Sun", 1E26, self.nonZero, Vector(4e4, 0, 0),
self.nonZero3)
print(body.calcKineticEnergy())
self.assertTrue(
System.nearly_equal(body.calcKineticEnergy(), 8e34, 1e-4))
def test_ShouldNotMoveAtZeroVelocityAndAcceleration(self):
body = CelestialBody("Sun", 1E26, self.zero, self.zero, self.zero)
body.update(10000)
self.assertTrue(body.position == self.zero)
def test_ShouldMoveAtIncreasingRateOfChangeOfPositionWithConstantAcceleration(
self):
body = CelestialBody("Sun", 1E26, self.nonZero, self.nonZero2,
self.nonZero3)
body.update(1)
self.assertTrue(body.position == Vector(14.5, 9.5, 8.5))
def test_ShouldMoveAtIncreasingVelocityWithConstantAcceleration(self):
body = CelestialBody("Sun", 1E26, self.nonZero, self.nonZero2,
self.nonZero3)
body.update(1)
self.assertTrue(body.velocity == Vector(15, 10, 5))
def test_ShouldMoveInSmallTimeIntervalAtZeroAcceleration(self):
body = CelestialBody("Sun", 1E26, self.nonZero, self.nonZero2,
self.zero)
body.update(0.25)
self.assertTrue(body.position == Vector(5, 4.25, 5.5))
def test_ShouldReturnMomentumWhenGivenMassAndVelocity(self):
body = CelestialBody("Sun", 1E26, self.nonZero, Vector(4e4, 0, 0),
self.nonZero3)
self.assertTrue(body.calcMomentum() == Vector(4e30, 0, 0))
pygame.display.set_caption("Orbital Simulator")
# Set up the drawing window
WIDTH = 1000
HEIGHT = 1000
screen = pygame.display.set_mode((WIDTH, HEIGHT))
alpha_surf = pygame.Surface(screen.get_size(),
pygame.SRCALPHA) # alpha surface for trails
FramePerSec = pygame.time.Clock()
font = pygame.font.SysFont('Arial', 20)
# Adding Planets
# earth
planetsList.append(
CelestialBody("Earth", Vector2(500, 500 + normalize_distance(147100000)),
5.97219e24, 0, (0, 0, 255), normalize_distance(30.29), 0, 5))
# moon
# mercury
planetsList.append(
CelestialBody("Mercury", Vector2(500, 500 + normalize_distance(46000000)),
3.285e23, 1, (200, 100, 30), normalize_distance(58.98), 0,
3))
# venus
planetsList.append(
CelestialBody("Venus", Vector2(500, 500 + normalize_distance(107476000)),
4.867e24, 2, (234, 213, 191), normalize_distance(35.26), 0,
4))
# mars
planetsList.append(
CelestialBody("Mars", Vector2(500, 500 + normalize_distance(206600000)),
6.39e23, 3, (200, 20, 20), normalize_distance(26.50), 0, 4))
