WIP - RESET THIS

WIP RESET THIS
This commit is contained in:
Cat Flynn 2022-09-05 22:13:53 +01:00
parent bc28d4d172
commit 5197362280
13 changed files with 176 additions and 79 deletions

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@ -1,7 +1,7 @@
[gd_scene load_steps=3 format=2] [gd_scene load_steps=3 format=2]
[ext_resource path="res://scenes/OrbitCamera.tscn" type="PackedScene" id=3] [ext_resource path="res://scenes/OrbitCamera.tscn" type="PackedScene" id=3]
[ext_resource path="res://scenes/orbits/OrbitSystem.tscn" type="PackedScene" id=4] [ext_resource path="res://scenes/orbits/Barycenter.tscn" type="PackedScene" id=4]
[node name="Main" type="Node2D"] [node name="Main" type="Node2D"]
@ -10,9 +10,8 @@ transform = Transform( 0.515898, 0.606099, -0.605386, -0.393123, 0.795389, 0.461
[node name="OrbitCamera" parent="." instance=ExtResource( 3 )] [node name="OrbitCamera" parent="." instance=ExtResource( 3 )]
[node name="Orbit System" parent="." instance=ExtResource( 4 )] [node name="Barycenter" parent="." instance=ExtResource( 4 )]
transform = Transform( 0.856869, 0.3292, -0.396741, 0.0949996, 0.655565, 0.749139, 0.506706, -0.679604, 0.53046, -0.599122, 0, 0 ) transform = Transform( 0.856869, 0.3292, -0.396741, 0.0949996, 0.655565, 0.749139, 0.506706, -0.679604, 0.53046, -0.599122, 0, 0 )
SemiMajorAxis = 6.166 SemiMajorAxis = 6.166
Eccentricity = 0.239 Eccentricity = 0.239
Period = 1.0
_speed = 0.877 _speed = 0.877

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@ -3,20 +3,17 @@
[ext_resource path="res://scripts/orbits/OrbitSystem.cs" type="Script" id=1] [ext_resource path="res://scripts/orbits/OrbitSystem.cs" type="Script" id=1]
[ext_resource path="res://scenes/orbits/Planet.tscn" type="PackedScene" id=2] [ext_resource path="res://scenes/orbits/Planet.tscn" type="PackedScene" id=2]
[node name="Orbit System" type="Spatial"] [node name="Barycenter" type="Spatial"]
script = ExtResource( 1 ) script = ExtResource( 1 )
SemiMajorAxis = 6.881 SemiMajorAxis = 6.881
Eccentricity = 0.399 Eccentricity = 0.399
Period = 10.0
_a = NodePath("Planet A") _a = NodePath("Planet A")
_b = NodePath("Planet B") _b = NodePath("Planet B")
_barycenter = NodePath("Barycenter") _barycenter = NodePath("")
[node name="Barycenter" type="Spatial" parent="."]
[node name="Planet A" parent="." instance=ExtResource( 2 )] [node name="Planet A" parent="." instance=ExtResource( 2 )]
transform = Transform( 0.999977, 0.00603502, 0.00319089, -0.00604282, 0.999979, 0.0024369, -0.00317609, -0.00245615, 0.999992, 0, 0, 0 ) transform = Transform( 0.999977, 0.00603502, 0.00319089, -0.00604282, 0.999979, 0.0024369, -0.00317609, -0.00245615, 0.999992, 0, 0, 0 )
[node name="Planet B" parent="." instance=ExtResource( 2 )] [node name="Planet B" parent="." instance=ExtResource( 2 )]
transform = Transform( 0.5, 0, 0, 0, 0.5, 0, 0, 0, 0.5, -8.44634, 0, -3.53339 ) transform = Transform( 0.5, 0, 0, 0, 0.5, 0, 0, 0, 0.5, -9.62645, 0, -0.0287273 )
Mass = 0.125 Mass = 0.125

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@ -3,5 +3,5 @@ using System;
public interface IMassive public interface IMassive
{ {
float Mass { get; } double Mass { get; }
} }

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@ -0,0 +1,4 @@
public static class IMassiveExtensions
{
public static double U(this IMassive m) => Kepler.U(m.Mass);
}

6
scripts/orbits/IOrbit.cs Normal file
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@ -0,0 +1,6 @@
using Vim.Math3d;
public interface IOrbit : IEllipse
{
DVector2 GetPosition(float t);
}

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@ -0,0 +1,13 @@
using Vim.Math3d;
using static System.Math;
public static class IOrbitalElementsExtensions
{
/// <summary>
/// Get the Cartesian position on the orbit for a given mean anomaly.
/// </summary>
/// <param name="M">Mean anomaly</param>
/// <returns>Position</returns>
public static DVector2 GetEccentricPosition2D(this OrbitalElements elements, double M) =>
Kepler.GetEccentricPosition2D(elements.e, elements.a, M);
}

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@ -2,22 +2,49 @@ using Godot;
using System; using System;
using Vim.Math3d; using Vim.Math3d;
public class Orbit public class Orbit : IOrbit
{ {
// The position of the primary body relative to the ellipse - the #region IEllipse
// orbit itself is presented as being centred on the primary, but public double a => Ellipse.a;
// all our math is elliptical. public double b => Ellipse.b;
private DVector2 PrimaryPosition => Ellipse.Focus0; public double e => Ellipse.e;
public DVector2[] Foci => Ellipse.Foci;
#endregion
public Ellipse Ellipse { get; set; } public IEllipse Ellipse { get; set; }
private double U => Kepler.U(_massive.Mass);
private readonly IMassive _massive;
private readonly ILocation _satellite;
/// <summary>
/// An orbit is treated as one stationary body at one focus of the orbit's ellipse.
/// The satellite is treated as a massless point.
/// </summary>
/// <param name="massive">Mass of the object being orbited</param>
/// <param name="satellite">The orbiting body</param>
public Orbit(IMassive massive, ILocation satellite)
{
// semi-major axis is distance of satellite from origin
var a = satellite.Position.Magnitude();
// TODO: determine eccentricity better
var e = 0.8f;
this.Ellipse = new Ellipse(a, e);
_massive = massive;
_satellite = satellite;
}
public DVector3 GetPosition(float t) public DVector3 GetPosition(float t)
{ {
var a = Ellipse.a;
var e = Ellipse.e;
Kepler.GetPeriod(a, U);
// TODO: determine period from mass of orbiting bodies // TODO: determine period from mass of orbiting bodies
var P = 10f; var P = 10f;
var a = Ellipse.a;
var e = Ellipse.e;
var M = Kepler.GetMeanAnomaly(t, P); var M = Kepler.GetMeanAnomaly(t, P);
var E = Kepler.GetEccentricAnomaly(e, M) + Math.PI; var E = Kepler.GetEccentricAnomaly(e, M) + Math.PI;
@ -45,7 +72,7 @@ public class Orbit
float t = i / (float)steps; float t = i / (float)steps;
float a = t * Mathf.Tau; float a = t * Mathf.Tau;
var v2 = Ellipse.Focus0 + Ellipse.GetPosition(a); var v2 = Ellipse.Foci[0] + Ellipse.GetPosition(a);
geo.AddVertex(new Godot.Vector3 geo.AddVertex(new Godot.Vector3
{ {

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@ -1,13 +1,13 @@
using Godot; using Godot;
using System; using System;
using System.Collections.Generic;
using Vim.Math3d; using Vim.Math3d;
[Tool] [Tool]
public class OrbitSystem : Node, IMassive, ILocation public class OrbitSystem : Node, IPointMass
{ {
[Export] private NodePath _a; [Export]
[Export] private NodePath _b; private NodePath[] _pointMassPaths;
[Export] private NodePath _barycenter;
private double _semiMajorAxis; private double _semiMajorAxis;
[Export] [Export]
@ -40,66 +40,37 @@ public class OrbitSystem : Node, IMassive, ILocation
} }
} }
#region Point Masses private IPointMass[] _pointMasses;
private IPointMass Primary public IPointMass[] Orbiters
{ {
get get
{ {
if (_pointMasses[0] == null) if (_pointMasses == null)
{ {
InitPointMasses(); _pointMasses = new IPointMass[_pointMassPaths.Length];
// give each body an orbit around ourselves
for (int i = 0; i < _pointMassPaths.Length; i++)
{
_pointMasses[i] = GetNode<IPointMass>(_pointMassPaths[i]);
}
} }
return _pointMasses[0]; return _pointMasses;
} }
} }
private IPointMass Secondary
public double Mass
{ {
get get
{ {
if (_pointMasses[1] == null) double mass = 0;
foreach (var pointMass in _pointMasses)
{ {
InitPointMasses(); mass += pointMass.Mass;
} }
return _pointMasses[1]; return mass;
} }
} }
private readonly IPointMass[] _pointMasses = new IPointMass[2]; public DVector3 Position { get; set; }
private void InitPointMasses()
{
var a = GetNode<IPointMass>(_a);
var b = GetNode<IPointMass>(_b);
if (a.Mass > b.Mass)
{
_pointMasses[0] = a;
_pointMasses[1] = b;
}
else
{
_pointMasses[0] = b;
_pointMasses[1] = a;
}
}
#endregion
public float Mass => Primary.Mass + Secondary.Mass;
public DVector3 Position
{
get => Barycenter;
set => Barycenter = value;
}
public DVector3 Barycenter
{
get
{
var p0 = Primary.Position;
var p1 = Secondary.Position;
return p0.Lerp(p1, .5f);
}
// TODO - make setting the berycenter do something sensible?
set => _ = value;
}
private Orbit _orbit = null; private Orbit _orbit = null;
private Orbit Orbit private Orbit Orbit
@ -148,6 +119,6 @@ public class OrbitSystem : Node, IMassive, ILocation
Orbit.Ellipse = new Ellipse(SemiMajorAxis, Eccentricity); Orbit.Ellipse = new Ellipse(SemiMajorAxis, Eccentricity);
Orbit.Draw(OrbitGeometry); Orbit.Draw(OrbitGeometry);
Secondary.Position = Orbit.GetPosition(_time); Orbiter.Position = Orbit.GetPosition(_time);
} }
} }

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@ -0,0 +1,46 @@
public struct OrbitalElements
{
private Ellipse _ellipse;
/// <summary>
/// Semi-major axis in AU
/// </summary>
public double a => _ellipse.a;
/// <summary>
/// Eccentricity
/// </summary>
public double e => _ellipse.e;
/// <summary>
/// Inclination in degrees
/// </summary>
public double i { get; private set; }
/// <summary>
/// Argument of ascending node in degrees
/// </summary>
public double W { get; private set; }
/// <summary>
/// Argument of periapsis in degrees
/// </summary>
public double p { get; private set; }
/// <summary>
/// Mean anomaly at epoch
/// </summary>
public double M0 { get; private set; }
/// <summary>
///
/// </summary>
/// <param name="a">Semi-major axis in AU</param>
/// <param name="e">eccentricity</param>
/// <param name="i">Inclination in degrees</param>
/// <param name="W">Argument of ascending node in degrees</param>
/// <param name="p">Argument of periapsis in degrees</param>
/// <param name="M0">Mean anomaly at epoch</param>
public OrbitalElements(double a, double e, double i, double W, double p, double M0)
{
_ellipse = new Ellipse(a, e);
this.i = i;
this.W = W;
this.p = p;
this.M0 = M0;
}
}

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@ -6,7 +6,7 @@ using Vim.Math3d;
public class Planet : Spatial, IPointMass public class Planet : Spatial, IPointMass
{ {
[Export] [Export]
public float Mass { get; set; } public double Mass { get; set; }
private DVector3? _position; private DVector3? _position;
public DVector3 Position public DVector3 Position

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@ -2,7 +2,7 @@ using Godot;
using System; using System;
using Vim.Math3d; using Vim.Math3d;
public struct Ellipse public struct Ellipse : IEllipse
{ {
public Ellipse(double a = 1, double e = 0) public Ellipse(double a = 1, double e = 0)
{ {
@ -12,6 +12,16 @@ public struct Ellipse
// TODO: this is an immutable struct, so initialise everything else // TODO: this is an immutable struct, so initialise everything else
// in the constructor to avoid recalculating properties whenever // in the constructor to avoid recalculating properties whenever
// they are accessed // they are accessed
Apisides = new Apisides(a, e);
b = Math.Sqrt(Apisides.max * Apisides.min);
var d = Math.Sqrt(a * a - b * b);
Foci = new DVector2[]
{
new DVector2(-d, 0),
new DVector2(d, 0)
};
} }
/// <summary> /// <summary>
@ -29,8 +39,7 @@ public struct Ellipse
/// <summary> /// <summary>
/// Semi-minor axis /// Semi-minor axis
/// </summary> /// </summary>
public double b => SemiMinorAxis; public double b { get; }
public double SemiMinorAxis => Math.Sqrt(Apisides.max * Apisides.min);
/// <summary> /// <summary>
/// Get a position on the auxiliary circle /// Get a position on the auxiliary circle
@ -40,13 +49,10 @@ public struct Ellipse
public DVector2 GetAuxiliaryPosition2D(double t = 0) => public DVector2 GetAuxiliaryPosition2D(double t = 0) =>
new DVector2(Math.Cos(t), Math.Sin(t)) * a; new DVector2(Math.Cos(t), Math.Sin(t)) * a;
private Apisides Apisides => new Apisides(a, e); private Apisides Apisides { get; }
public DVector2 GetPosition(double t) => public DVector2[] Foci { get; }
new DVector2(Math.Cos(t) * a, Math.Sin(t) * b);
public DVector2 Focus0 => new DVector2(-GetFocusDistance(), 0);
public DVector2 Focus1 => new DVector2(GetFocusDistance(), 0);
private double GetFocusDistance() => Math.Sqrt(a * a - b * b); private double GetFocusDistance() => Math.Sqrt(a * a - b * b);
} }

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@ -0,0 +1,20 @@
using Godot;
using System;
using Vim.Math3d;
public interface IEllipse
{
/// <summary>
/// Semi-major axis
/// </summary>
double a { get; }
double b { get; }
/// <summary>
/// Eccentricity
/// </summary>
double e { get; }
/// <summary>
/// Positions of the two foci of the ellipse
/// </summary>
DVector2[] Foci { get; }
}

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@ -0,0 +1,8 @@
using Vim.Math3d;
using System;
public static class IEllipseExtensions
{
public static DVector2 GetPosition(this IEllipse e, double t) =>
new DVector2(Math.Cos(t) * e.a, Math.Sin(t) * e.b);
}