set moon orbit phases according to real time clock

src/commands.rs

@@ -19,6 +19,7 @@ use crate::{actor, camera, chat, hud, nature, shading, skeleton, var, world};
 use regex::Regex;
 use std::f32::consts::PI;
 use std::f64::consts::PI as PI64;
+use std::time::SystemTime;
 
 pub struct CommandsPlugin;
 impl Plugin for CommandsPlugin {
@@ -68,6 +69,9 @@ struct ParserState {
     is_sun: bool,
     is_moon: bool,
     is_point_of_interest: bool,
+    orbit_distance: Option<f64>,
+    orbit_object_id: Option<String>,
+    orbit_phase: Option<f64>,
     has_physics: bool,
     has_ring: bool,
     wants_maxrotation: Option<f64>,
@@ -119,6 +123,9 @@ impl Default for ParserState {
             is_sun: false,
             is_moon: false,
             is_point_of_interest: false,
+            orbit_distance: None,
+            orbit_object_id: None,
+            orbit_phase: None,
             has_physics: true,
             has_ring: false,
             wants_maxrotation: None,
@@ -227,14 +234,20 @@ pub fn load_defs(
             ["relativeto", id] => {
                 state.relative_to = Some(id.to_string());
             }
+            ["orbitaround", object_id, radius_str] => {
+                if let Ok(r) = radius_str.parse::<f64>() {
+                    state.orbit_distance = Some(r);
+                    state.orbit_object_id = Some(object_id.to_string());
+                }
+                else {
+                    error!("Can't parse float: {line}");
+                    continue;
+                }
+            }
             ["orbit", radius_str, phase_str] => {
                 if let (Ok(r), Ok(phase)) = (radius_str.parse::<f64>(), phase_str.parse::<f64>()) {
-                    let phase_deg = phase * PI64 * 2.0;
+                    state.orbit_distance = Some(r);
-                    state.pos = DVec3::new(
+                    state.orbit_phase = Some(phase * PI64 * 2.0);
-                        state.pos.x + r * phase_deg.cos(),
-                        state.pos.y,
-                        state.pos.z + r * phase_deg.sin(),
-                    );
                 }
                 else {
                     error!("Can't parse float: {line}");
@@ -492,7 +505,7 @@ fn spawn_entities(
         let state = &state_wrapper.0;
         if state.class == DefClass::Actor {
             // Preprocessing
-            let relative_pos = if let Some(id) = &state.relative_to {
+            let mut absolute_pos = if let Some(id) = &state.relative_to {
                 match id2pos.0.get(&id.to_string()) {
                     Some(pos) => {
                         state.pos + *pos
@@ -505,6 +518,30 @@ fn spawn_entities(
             } else {
                 state.pos
             };
+            if let Some(r) = state.orbit_distance {
+                let phase_radians: f64 = if let Some(phase_radians) = state.orbit_phase {
+                    phase_radians
+                } else if let Some(id) = &state.orbit_object_id {
+                    let mass = match id.as_str() {
+                        "jupiter" => nature::JUPITER_MASS,
+                        _ => {
+                            error!("Found no mass for object `{id}`");
+                            continue;
+                        }
+                    };
+                    let orbital_period = nature::simple_orbital_period(mass, r);
+                    if let Ok(epoch) = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
+                        PI64 * 2.0 * (epoch.as_secs_f64() % orbital_period) / orbital_period
+                    } else {
+                        error!("Can't determine current time `{id}`");
+                        0.0
+                    }
+                } else {
+                    error!("if state.orbit_distance is set, then either state.orbit_object_id or state.orbit_phase must be set as well.");
+                    continue;
+                };
+                absolute_pos += nature::phase_dist_to_coords(phase_radians, r);
+            }
             let scale = Vec3::splat(if state.is_sun {
                 5.0
             } else if state.is_moon && settings.large_moons {
@@ -526,7 +563,7 @@ fn spawn_entities(
             actor.insert(SleepingDisabled);
             actor.insert(world::DespawnOnPlayerDeath);
             actor.insert(actor::HitPoints::default());
-            actor.insert(Position::from(relative_pos));
+            actor.insert(Position::from(absolute_pos));
             actor.insert(Rotation::from(state.rotation));
             if state.is_sphere {
                 let sphere_texture_handle = if let Some(model) = &state.model {
@@ -653,7 +690,7 @@ fn spawn_entities(
             }
             if !state.id.is_empty() {
                 actor.insert(actor::Identifier(state.id.clone()));
-                id2pos.0.insert(state.id.clone(), relative_pos);
+                id2pos.0.insert(state.id.clone(), absolute_pos);
             }
             if !state.chat.is_empty() {
                 actor.insert(chat::Talker {
@@ -730,10 +767,10 @@ fn spawn_entities(
                             ring_radius: nature::JUPITER_RING_RADIUS as f32,
                             jupiter_radius: nature::JUPITER_RADIUS as f32,
                         }),
-                        transform: Transform::from_translation(relative_pos.as_vec3()),
+                        transform: Transform::from_translation(absolute_pos.as_vec3()),
                         ..default()
                     },
-                    Position::new(relative_pos),
+                    Position::new(absolute_pos),
                     Rotation::from(Quat::IDENTITY),
                     //Rotation::from(Quat::from_rotation_x(-0.3f32.to_radians())),
                     NotShadowCaster,

src/data/defs.txt

@@ -152,7 +152,7 @@ actor 0 0 0 io
     name Io
     id io
     relativeto jupiter
-    orbit 421700e3 0.65
+    orbitaround jupiter 421700e3
     scale 1822e3
     rotationy -0.40
     rotationx -0.50
@@ -165,7 +165,7 @@ actor 0 0 0 europa
     name Europa
     id europa
     relativeto jupiter
-    orbit 670900e3 0.35
+    orbitaround jupiter 670900e3
     scale 1561e3
     rotationy 0.20
     rotationx -0.50
@@ -178,7 +178,7 @@ actor 0 0 0 ganymede
     name Ganymede
     id ganymede
     relativeto jupiter
-    orbit 1070400e3 0.93
+    orbitaround jupiter 1070400e3
     scale 2634e3
     rotationy -0.40
     rotationx -0.50
@@ -191,7 +191,7 @@ actor 0 0 0 callisto
     name Callisto
     id callisto
     relativeto jupiter
-    orbit 1882700e3 0.45
+    orbitaround jupiter 1882700e3
     scale 2410e3
     rotationy -0.40
     rotationx -0.50
@@ -204,7 +204,7 @@ actor 0 0 0 moonlet
     name Thebe
     relativeto jupiter
     id thebe
-    orbit 221900e3 0.66
+    orbitaround jupiter 221900e3
     scale 50e3
     angularmomentum 0 0.025 0
     actor -55e3 44e3 0 suitv2
@@ -226,7 +226,7 @@ actor 0 0 0 moonlet
     name Metis
     relativeto jupiter
     id metis
-    orbit 128000e3 0.8
+    orbitaround jupiter 128000e3
     scale 21.5e3
     angularmomentum 0 0.025 0
 
@@ -234,7 +234,7 @@ actor 0 0 0 moonlet
     name Adrastea
     relativeto jupiter
     id adrastea
-    orbit 129000e3 0.5
+    orbitaround jupiter 129000e3
     scale 8.2e3
     angularmomentum 0 0.025 0
 
@@ -242,7 +242,7 @@ actor 0 0 0 moonlet
     name Amalthea
     relativeto jupiter
     id amalthea
-    orbit 181365.84e3 0.2
+    orbitaround jupiter 181365.84e3
     scale 83.5e3
     angularmomentum 0 0.025 0
 

src/nature.rs

@@ -10,6 +10,9 @@
 //
 // This module manages the messy, impure parts of our universe.
 
+use bevy::math::DVec3;
+use std::f64::consts::PI as PI64;
+
 pub const OXYGEN_USE_KG_PER_S: f32 = 1e-5;
 pub const OXY_S: f32 = OXYGEN_USE_KG_PER_S;
 pub const OXY_M: f32 = OXYGEN_USE_KG_PER_S * 60.0;
@@ -20,10 +23,12 @@ pub const PARSEC2METER: f64 = 3.0857e16;
 pub const DIST_JUPTER_SUN: f64 = 778479.0e6;
 pub const EARTH_GRAVITY: f32 = 9.81;
 pub const C: f64 = 299792458.0; // m/s
+pub const G: f64 = 6.6743015e-11; // Gravitational constant in Nm²/kg²
 
 pub const SOL_RADIUS: f64 =          696_300_000.0;
 pub const JUPITER_RADIUS: f64 =       71_492_000.0;
 pub const JUPITER_RING_RADIUS: f64 = 229_000_000.0;
+pub const JUPITER_MASS: f64 = 1.8982e27;
 
 // Each star's values: (x, y, z, magnitude, color index, distance, name)
 pub const STARS: &[(f32, f32, f32, f32, f32, f32, &str)] = &include!("data/stars.in");
@@ -139,3 +144,15 @@ pub fn lorenz_factor(speed: f64) -> f64 {
 pub fn lorenz_factor_custom_c(speed: f64, c: f64) -> f64 {
     (1.0 - (speed.powf(2.0) / c.powf(2.0))).sqrt()
 }
+
+pub fn simple_orbital_period(mass: f64, distance: f64) -> f64 {
+    return 2.0 * PI64 * (distance.powf(3.0) / (G * mass)).sqrt();
+}
+
+pub fn phase_dist_to_coords(phase_radians: f64, distance: f64) -> DVec3 {
+    return DVec3::new(
+        distance * phase_radians.cos(),
+        0.0,
+        distance * phase_radians.sin(),
+    );
+}