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Finished AB 1

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Lorenz Stechauner
2022-03-17 13:53:41 +01:00
parent 971beaf1ae
commit 155dc74001
4 changed files with 107 additions and 216 deletions
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5
src/Aufgabe1Test.java
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@ -6,8 +6,6 @@ public class Aufgabe1Test {
//test classes Body and Vector3
/* TODO: remove this line
// create two bodies
Body sun = new Body(1.989e30,new Vector3(0,0,0),new Vector3(0,0,0));
Body earth = new Body(5.972e24,new Vector3(-1.394555e11,5.103346e10,0),new Vector3(-10308.53,-28169.38,0));
@ -29,9 +27,6 @@ public class Aufgabe1Test {
// check distance to target position (should be zero)
testValue(earth.distanceTo(targetPositionEarth), 0);
// TODO: remove this line */
}
public static void testComparison(Object first, Object second, boolean expected) {

61
src/Body.java
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@ -1,22 +1,20 @@
import codedraw.CodeDraw;
import java.awt.*;
// This class represents celestial bodies like stars, planets, asteroids, etc..
public class Body {
private double mass;
private Vector3 massCenter; // position of the mass center.
private Vector3 currentMovement;
//TODO: change modifiers.
public double mass;
public Vector3 massCenter; // position of the mass center.
public Vector3 currentMovement;
//TODO: define constructor.
public Body(double mass, Vector3 massCenter, Vector3 currentMovement) {
this.mass = mass;
this.massCenter = massCenter;
this.currentMovement = currentMovement;
}
// Returns the distance between the mass centers of this body and the specified body 'b'.
public double distanceTo(Body b) {
//TODO: implement method.
return 0;
return massCenter.distanceTo(b.massCenter);
}
// Returns a vector representing the gravitational force exerted by 'b' on this body.
@ -25,9 +23,11 @@ public class Body {
// and G being the gravitational constant.
// Hint: see simulation loop in Simulation.java to find out how this is done.
public Vector3 gravitationalForce(Body b) {
//TODO: implement method.
return null;
Vector3 direction = b.massCenter.minus(massCenter);
double distance = direction.length();
direction.normalize();
double force = Simulation.G * mass * b.mass / (distance * distance);
return direction.times(force);
}
// Moves this body to a new position, according to the specified force vector 'force' exerted
@ -35,25 +35,33 @@ public class Body {
// (Movement depends on the mass of this body, its current movement and the exerted force.)
// Hint: see simulation loop in Simulation.java to find out how this is done.
public void move(Vector3 force) {
// F = m*a -> a = F/m
Vector3 newPosition = massCenter.plus(force.times(1.0 / mass)).plus(currentMovement);
//TODO: implement method.
// new minus old position.
Vector3 newMovement = newPosition.minus(massCenter);
// update body state
massCenter = newPosition;
currentMovement = newMovement;
}
// Returns the approximate radius of this body.
// (It is assumed that the radius r is related to the mass m of the body by r = m ^ 0.5,
// where m and r measured in solar units.)
public double radius() {
//TODO: implement method.
return 0d;
return SpaceDraw.massToRadius(mass);
}
// Returns a new body that is formed by the collision of this body and 'b'. The impulse
// of the returned body is the sum of the impulses of 'this' and 'b'.
public Body merge(Body b) {
//TODO: implement method.
return null;
double mass = this.mass + b.mass;
return new Body(
mass,
massCenter.times(this.mass).plus(b.massCenter.times(b.mass)).times(1.0 / mass),
currentMovement.times(this.mass).plus(b.currentMovement.times(b.mass)).times(1.0 / mass)
);
}
// Draws the body to the specified canvas as a filled circle.
@ -62,17 +70,18 @@ public class Body {
// in 'Simulation.java').
// Hint: call the method 'drawAsFilledCircle' implemented in 'Vector3'.
public void draw(CodeDraw cd) {
//TODO: implement method.
cd.setColor(SpaceDraw.massToColor(mass));
massCenter.drawAsFilledCircle(cd, SpaceDraw.massToRadius(mass));
}
// Returns a string with the information about this body including
// mass, position (mass center) and current movement. Example:
// "5.972E24 kg, position: [1.48E11,0.0,0.0] m, movement: [0.0,29290.0,0.0] m/s."
public String toString() {
//TODO: implement method.
return "";
return String.format(
"%f kg, position: %s m, movement: %s m/s.",
mass, massCenter.toString(), currentMovement.toString()
);
}
}

183
src/Simulation.java
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@ -3,7 +3,14 @@ import codedraw.CodeDraw;
import java.awt.*;
import java.util.Random;
// TODO: insert answers to questions (Zusatzfragen) in 'Aufgabenblatt1.md' as comment.
// 1. Datenkapselung: Zusammenfassen von Methoden und Variablen zu Einheit.
// Die `static` Methoden von `Simulation` nach `Body` oder `Vector3` verschieben.
// 2. Data Hiding: Verstecken vor Zugriffen von außen.
// Attribute von `Body` und `Vector3` auf `private` setzen.
// 3. Beim Methodenaufruf steht links vom `.` entweder das Objekt, oder die Klasse. In Java beginnen Variablennamen
// üblicherweise mit Kleinbuchstaben und Klassennamen üblicherweise mit einem Großbuchstaben.
// Simulates the formation of a massive solar system.
public class Simulation {
@ -32,9 +39,6 @@ public class Simulation {
// The main simulation method using instances of other classes.
public static void main(String[] args) {
//TODO: change implementation of this method according to 'Aufgabenblatt1.md'.
// simulation
CodeDraw cd = new CodeDraw();
Body[] bodies = new Body[NUMBER_OF_BODIES];
@ -43,18 +47,19 @@ public class Simulation {
Random random = new Random(2022);
for (int i = 0; i < bodies.length; i++) {
bodies[i] = new Body();
bodies[i].mass = Math.abs(random.nextGaussian()) * OVERALL_SYSTEM_MASS / bodies.length; // kg
bodies[i].massCenter = new Vector3();
bodies[i].currentMovement = new Vector3();
bodies[i].massCenter.x = 0.2 * random.nextGaussian() * AU;
bodies[i].massCenter.y = 0.2 * random.nextGaussian() * AU;
bodies[i].massCenter.z = 0.2 * random.nextGaussian() * AU;
bodies[i].currentMovement.x = 0 + random.nextGaussian() * 5e3;
bodies[i].currentMovement.y = 0 + random.nextGaussian() * 5e3;
bodies[i].currentMovement.z = 0 + random.nextGaussian() * 5e3;
bodies[i] = new Body(
Math.abs(random.nextGaussian()) * OVERALL_SYSTEM_MASS / bodies.length, // kg
new Vector3(
0.2 * random.nextGaussian() * AU,
0.2 * random.nextGaussian() * AU,
0.2 * random.nextGaussian() * AU
),
new Vector3(
0 + random.nextGaussian() * 5e3,
0 + random.nextGaussian() * 5e3,
0 + random.nextGaussian() * 5e3
)
);
}
double seconds = 0;
@ -66,9 +71,8 @@ public class Simulation {
// merge bodies that have collided
for (int i = 0; i < bodies.length; i++) {
for (int j = i + 1; j < bodies.length; j++) {
if (distance(bodies[j].massCenter, bodies[i].massCenter) <
SpaceDraw.massToRadius(bodies[j].mass) + SpaceDraw.massToRadius(bodies[i].mass)) {
bodies[i] = merge(bodies[i], bodies[j]);
if (bodies[j].distanceTo(bodies[i]) < bodies[j].radius() + bodies[i].radius()) {
bodies[i] = bodies[i].merge(bodies[j]);
Body[] bodiesOneRemoved = new Body[bodies.length - 1];
for (int k = 0; k < bodiesOneRemoved.length; k++) {
bodiesOneRemoved[k] = bodies[k < j ? k : k + 1];
@ -88,8 +92,8 @@ public class Simulation {
forceOnBody[i] = new Vector3(); // begin with zero
for (int j = 0; j < bodies.length; j++) {
if (i != j) {
Vector3 forceToAdd = gravitationalForce(bodies[i], bodies[j]);
forceOnBody[i] = plus(forceOnBody[i], forceToAdd);
Vector3 forceToAdd = bodies[i].gravitationalForce(bodies[j]);
forceOnBody[i] = forceOnBody[i].plus(forceToAdd);
}
}
}
@ -97,7 +101,7 @@ public class Simulation {
// for each body (with index i): move it according to the total force exerted on it.
for (int i = 0; i < bodies.length; i++) {
move(bodies[i], forceOnBody[i]);
bodies[i].move(forceOnBody[i]);
}
// show all movements in the canvas only every hour (to speed up the simulation)
@ -107,7 +111,7 @@ public class Simulation {
// draw new positions
for (Body body : bodies) {
draw(cd, body);
body.draw(cd);
}
// show new positions
@ -117,137 +121,4 @@ public class Simulation {
}
}
//TODO: remove static methods below.
// Draws a body in the 'cd' canvas showing a projection onto the (x,y)-plane. The body's mass
// center coordinates and its radius are transformed into canvas coordinates. The color of
// the body corresponds to the temperature of the body, assuming the relation of mass and
// temperature of a main sequence star.
// The canvas is assumed to show a quadratic SECTION_SIZE x SECTION_SIZE
// section of space centered arround (x, y) = (0, 0).
public static void draw(CodeDraw cd, Body b) {
cd.setColor(SpaceDraw.massToColor(b.mass));
drawAsFilledCircle(cd, b.massCenter, SpaceDraw.massToRadius(b.mass));
}
// Draws a filled circle in the 'cd' canvas unsing the (x,y)-coordinates of 'center'
// Coordinates and 'radius' are transformed into canvas coordinates. The canvas is assumed
// to show a quadratic SECTION_SIZE x SECTION_SIZE projection of space centered arround (x, y) =
// (0, 0).
public static void drawAsFilledCircle(CodeDraw cd, Vector3 center, double radius) {
double x = cd.getWidth() * (center.x + Simulation.SECTION_SIZE / 2) / Simulation.SECTION_SIZE;
double y = cd.getWidth() * (center.y + Simulation.SECTION_SIZE / 2) / Simulation.SECTION_SIZE;
radius = cd.getWidth() * radius / Simulation.SECTION_SIZE;
cd.fillCircle(x, y, Math.max(radius, 1.5));
}
// Returns a vector representing the gravitational force exerted by body 'b2' on body 'b1'.
// The gravitational Force F is calculated by F = G*(m1*m2)/(r*r), with m1 and m2 being the masses of the objects
// interacting, r being the distance between the centers of the masses and G being the gravitational constant.
// To calculate the force exerted on b1, simply multiply the normalized vector pointing from b1 to b2 with the
// calculated force.
public static Vector3 gravitationalForce(Body b1, Body b2) {
Vector3 direction = minus(b2.massCenter, b1.massCenter);
double distance = length(direction);
normalize(direction);
double force = G * b1.mass * b2.mass / (distance * distance);
return times(direction, force);
}
// Returns a new body that is formed by the collision of 'b1' and 'b2'. The impulse
// of the returned body is the sum of the impulses of 'b1' and 'b2'.
public static Body merge(Body b1, Body b2) {
Body result = new Body();
result.mass = b1.mass + b2.mass;
result.massCenter = times(plus(times(b1.massCenter, b1.mass), times(b2.massCenter,
b2.mass)),
1 / result.mass);
result.currentMovement =
times(plus(times(b1.currentMovement, b1.mass), times(b2.currentMovement, b2.mass)),
1.0 / result.mass);
return result;
}
// Move the body 'b' according to the 'force' excerted on it.
public static void move(Body b, Vector3 force) {
Vector3 newPosition = plus(
plus(b.massCenter,
times(force, 1 / b.mass)
// F = m*a -> a = F/m
),
b.currentMovement
);
// new minus old position.
Vector3 newMovement = minus(newPosition, b.massCenter);
// update body state
b.massCenter = newPosition;
b.currentMovement = newMovement;
}
// Returns the norm of v1-v2.
public static double distance(Vector3 v1, Vector3 v2) {
double dX = v1.x - v2.x;
double dY = v1.y - v2.y;
double dZ = v1.z - v2.z;
return Math.sqrt(dX * dX + dY * dY + dZ * dZ);
}
// Returns v1+v2.
public static Vector3 plus(Vector3 v1, Vector3 v2) {
Vector3 result = new Vector3();
result.x = v1.x + v2.x;
result.y = v1.y + v2.y;
result.z = v1.z + v2.z;
return result;
}
// Returns v1-v2.
public static Vector3 minus(Vector3 v1, Vector3 v2) {
Vector3 result = new Vector3();
result.x = v1.x - v2.x;
result.y = v1.y - v2.y;
result.z = v1.z - v2.z;
return result;
}
// Returns v*d.
public static Vector3 times(Vector3 v, double d) {
Vector3 result = new Vector3();
result.x = v.x * d;
result.y = v.y * d;
result.z = v.z * d;
return result;
}
// Returns the norm of 'v'.
public static double length(Vector3 v) {
return distance(v, new Vector3()); // distance to origin.
}
// Normalizes the specified vector 'v': changes the length of the vector such that its length
// becomes one. The direction and orientation of the vector is not affected.
public static void normalize(Vector3 v) {
double length = length(v);
v.x /= length;
v.y /= length;
v.z /= length;
}
}

74
src/Vector3.java
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@ -1,73 +1,89 @@
import codedraw.CodeDraw;
import java.awt.*;
// This class represents vectors in a 3D vector space.
public class Vector3 {
//TODO: change modifiers.
public double x;
public double y;
public double z;
private double x;
private double y;
private double z;
//TODO: define constructor.
public Vector3() {
this(0);
}
public Vector3(double v) {
this(v, v, v);
}
public Vector3(double x, double y, double z) {
this.x = x;
this.y = y;
this.z = z;
}
// Returns the sum of this vector and vector 'v'.
public Vector3 plus(Vector3 v) {
//TODO: implement method.
return null;
Vector3 result = new Vector3();
result.x = x + v.x;
result.y = y + v.y;
result.z = z + v.z;
return result;
}
// Returns the product of this vector and 'd'.
public Vector3 times(double d) {
//TODO: implement method.
return null;
Vector3 result = new Vector3();
result.x = x * d;
result.y = y * d;
result.z = z * d;
return result;
}
// Returns the sum of this vector and -1*v.
public Vector3 minus(Vector3 v) {
//TODO: implement method.
return null;
Vector3 result = new Vector3();
result.x = x - v.x;
result.y = y - v.y;
result.z = z - v.z;
return result;
}
// Returns the Euclidean distance of this vector
// to the specified vector 'v'.
public double distanceTo(Vector3 v) {
//TODO: implement method.
return -1d;
double dX = x - v.x;
double dY = y - v.y;
double dZ = z - v.z;
return Math.sqrt(dX * dX + dY * dY + dZ * dZ);
}
// Returns the length (norm) of this vector.
public double length() {
//TODO: implement method.
return 0;
return distanceTo(new Vector3());
}
// Normalizes this vector: changes the length of this vector such that it becomes 1.
// The direction and orientation of the vector is not affected.
public void normalize() {
//TODO: implement method.
double length = length();
x /= length;
y /= length;
z /= length;
}
// Draws a filled circle with a specified radius centered at the (x,y) coordinates of this vector
// in the canvas associated with 'cd'. The z-coordinate is not used.
public void drawAsFilledCircle(CodeDraw cd, double radius) {
//TODO: implement method.
double x = cd.getWidth() * (this.x + Simulation.SECTION_SIZE / 2) / Simulation.SECTION_SIZE;
double y = cd.getWidth() * (this.y + Simulation.SECTION_SIZE / 2) / Simulation.SECTION_SIZE;
radius = cd.getWidth() * radius / Simulation.SECTION_SIZE;
cd.fillCircle(x, y, Math.max(radius, 1.5));
}
// Returns the coordinates of this vector in brackets as a string
// in the form "[x,y,z]", e.g., "[1.48E11,0.0,0.0]".
public String toString() {
//TODO: implement method.
return "";
return String.format("[%f,%f,%f]", x, y, z);
}
}