implementing save trajectory

Cargo.toml

@@ -7,9 +7,11 @@ authors = ["thomas"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+bincode = "1.3"
 clap = { version = "4.5.39", features = ["derive"] }
 env_logger = "0.11.8"
 glam = { version = "0.30.4", features = ["serde"] }
+humantime = "2.2.0"
 indicatif = "0.17.11"
 log = "0.4.27"
 once_cell = "1.21.3"

config/planets.json

@@ -1,11 +1,29 @@
 {
     "bodies": [
+        {
+            "name": "Mercury",
+            "mass": 3.30104e23,
+            "position": [4.6000e10, 0, 0],
+            "velocity": [0, 58970, 0]
+        },
+        {
+            "name": "Venus",
+            "mass": 4.867e24,
+            "position": [1.08941e11, 0, 0],
+            "velocity": [0, 34780, 0]
+        },
         {
             "name": "Earth",
             "mass": 5.972e24,
             "position": [1.47095e11, 0, 0],
             "velocity": [0, 29290, 0]
         },
+        {
+            "name": "Moon",
+            "mass": 7.34767309e22,
+            "position": [149982270700, 0, 0],
+            "velocity": [0, 30822, 0]
+        },
         {
             "name": "Sun",
             "mass": 1.989e30,
@@ -13,4 +31,4 @@
             "velocity": [0, 0, 0]
         }
     ]
-} 
+} 

src/config.rs

@@ -1,7 +1,8 @@
 use crate::types;
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 
-#[derive(Debug, Deserialize)]
+
+#[derive(Debug, Deserialize, Serialize)]
 pub struct Body {
     pub name: String,
     pub mass: types::Mass,

src/main.rs

@@ -3,11 +3,13 @@ use std::error::Error;
 use std::fs::File;
 use std::io::BufReader;
 use std::path::Path;
+use std::time::Duration;
 
 // External crates
 use clap::Parser;
 use log::{info, warn, error, debug, trace};
 use indicatif::{ProgressBar, ProgressStyle};
+use humantime;
 
 // Internal modules
 mod types;
@@ -15,7 +17,9 @@ mod config;
 mod simulator;
 
 // Specific uses from modules
-use crate::simulator::Simulator;
+use crate::simulator::Simulation;
+use crate::types::{norm_mass, norm_pos, norm_vel, norm_time, real_pos, real_vel};
+
 
 #[derive(Parser, Debug)]
 #[command(
@@ -29,9 +33,21 @@ struct Args {
     #[arg(short, long)]
     config: String,
 
+    /// Time to run simulation for (e.g. 10s, 5m, 2h, 100d)
+    #[arg(short, long, value_parser = humantime::parse_duration)]
+    time: Duration,
+
     ///Step size for simulation (seconds)
-    #[arg(short, long, default_value_t = 10)]
-    step_size: u8,
+    #[arg(short, long, default_value_t = 10.0)]
+    step_size: f64,
+
+    ///How often to update progress bar and save (seconds)
+    #[arg(short = 'P', long, default_value_t = 1000)]
+    steps_per_save: usize,
+
+    /// Filename to save trajectory to
+    #[arg(short, long)]
+    output_file: String,
 }
 
 fn read_config<P: AsRef<Path>>(path: P) -> Result<config::ConfigFile, Box<dyn Error>> {
@@ -55,13 +71,22 @@ fn main() {
         info!("Loaded {} with mass {:.3e} kg", body.name, body.mass);
         debug!("R_i = {:?}, V_i = {:?}", body.position, body.velocity);
     }
-    let steps: usize = 10000000;
-    let pb = ProgressBar::new(steps.try_into().unwrap());
+
+    let n_steps = (args.time.as_secs() as f64 / args.step_size) as usize;
+
+
+    let pb = ProgressBar::new(n_steps.try_into().unwrap());
     pb.set_style(
-    ProgressStyle::with_template("[{elapsed_precise}] {bar:40.cyan/blue} {pos:>3}/{len:3} {msg}")
+    ProgressStyle::with_template("[{elapsed_precise}] {bar:40.cyan/blue} {percent_precise}% {eta} {msg}")
         .unwrap()
         .progress_chars("=>-"),
     );
-    let mut sim = Simulator::new(conf.bodies, 0.5, 10000);
-    sim.run(steps, Some(|| pb.inc(10000)));
+
+    let mut sim = Simulation::new(
+        conf.bodies, 
+        norm_time(args.step_size), 
+        args.steps_per_save,
+        args.output_file,
+    );
+    sim.run(n_steps, Some(|| pb.inc(args.steps_per_save as u64)));
 }

src/simulator.rs

@@ -1,17 +1,33 @@
+use std::fs::OpenOptions;
+use std::io::BufWriter;
+
+use serde::{Deserialize, Serialize};
 use log::{info, warn, error, debug, trace};
 use glam::DVec3;
 
 use crate::config::Body;
-use crate::types::{norm_mass, norm_pos, norm_vel, norm_time, real_pos, real_vel};
+use crate::types::{norm_mass, norm_pos, norm_vel, norm_time, real_pos, real_vel, real_time};
 
-pub struct Simulator {
+pub struct Simulation {
     bodies: Vec<Body>,
     step_size: f64,
     steps_per_save: usize,
+    save_file: String 
 }
 
-impl Simulator {
-    pub fn new(mut bodies: Vec<Body>, mut step_size: f64, steps_per_save: usize) -> Self {
+#[derive(Serialize)]
+struct Snapshot<'a> {
+    time: f64,
+    bodies: &'a [Body],
+}
+
+impl Simulation {
+    pub fn new(
+        mut bodies: Vec<Body>, 
+        mut step_size: f64, 
+        steps_per_save: usize,
+        save_file: String,
+    ) -> Self {
         let n = bodies.len();
         for i in 0..n {
             bodies[i].mass = norm_mass(bodies[i].mass);
@@ -19,17 +35,31 @@ impl Simulator {
             bodies[i].velocity = norm_vel(bodies[i].velocity);
         }
         step_size = norm_time(step_size);
-        Self {bodies, step_size, steps_per_save}
+        Self {bodies, step_size, steps_per_save, save_file}
     }
 
     pub fn run<F>(&mut self, steps: usize, mut on_step: Option<F>)
     where F: FnMut() {
+        let file = OpenOptions::new()
+            .create(true)
+            .append(true)
+            .open(&self.save_file);
+        let mut writer = BufWriter::new(file.unwrap());
+
         for i in 0..steps {
             debug!("Step: {}", i);
             self.reset_accelerations();
             self.caclulate_accelerations();
             self.step_bodies();
-            if (i%self.steps_per_save == 0) {
+            if i % self.steps_per_save == 0 {
+                //save the state
+                let snapshot = Snapshot {
+                    time: real_time(i as f64*self.step_size),
+                    bodies: &self.bodies,
+                };
+
+                bincode::serialize_into(&mut writer, &snapshot);  
+                //Do the progress bar
                 if let Some(f) = &mut on_step {
                     f();
                 }

src/types.rs

@@ -1,3 +1,4 @@
+#![allow(unused)]
 use glam::DVec3;
 use once_cell::sync::Lazy;
 
@@ -23,62 +24,62 @@ const SUN_MASS: f64 = 1.989e30; //kg
 const SUN_RADIUS: f64 = 6.957e8; //meters
 
 const G: f64 = 6.67430e-11;
-const r_0: f64 = EARTH_RADIUS;
-const m_0: f64 = EARTH_MASS;
+const R_0: f64 = EARTH_RADIUS;
+const M_0: f64 = EARTH_MASS;
 
-static t_0: Lazy<f64> = Lazy::new(|| {
-    (r_0.powf(3.0) / (G * m_0)).sqrt()
+static T_0: Lazy<f64> = Lazy::new(|| {
+    (R_0.powf(3.0) / (G * M_0)).sqrt()
 });
 
 
 #[inline]
 pub fn norm_pos(pos: Position) -> Position {
-    pos / r_0
+    pos / R_0
 }
 
 #[inline]
 pub fn real_pos(pos: Position) -> Position {
-    pos * r_0
+    pos * R_0
 }
 
 #[inline]
 pub fn norm_mass(mass: Mass) -> Mass {
-    mass / m_0
+    mass / M_0
 }
 
 #[inline]
 pub fn real_mass(mass: Mass) -> Mass {
-    mass * m_0
+    mass * M_0
 }
 
 #[inline]
 pub fn norm_time(time: Time) -> Time {
-    time / *t_0
+    time / *T_0
 }
 
 #[inline]
 pub fn real_time(time: Time) -> Time {
-    time * *t_0
+    time * *T_0
 }
 
 #[inline]
 pub fn norm_vel(vel: Velocity) -> Velocity {
-    vel / (r_0 / *t_0)
+    vel / (R_0 / *T_0)
 }
 
 #[inline]
 pub fn real_vel(vel: Velocity) -> Velocity {
-    vel * (r_0 / *t_0)
+    vel * (R_0 / *T_0)
 }
 
 #[inline]
 pub fn norm_acc(acc: Acceleration) -> Acceleration {
-    acc / (r_0 / (*t_0 * *t_0))
+    acc / (R_0 / (*T_0 * *T_0))
 }
 
 #[inline]
 pub fn real_acc(acc: Acceleration) -> Acceleration {
-    acc * (r_0 / (*t_0 * *t_0))
+    acc * (R_0 / (*T_0 * *T_0))
 }
 
 #[inline]