From cd13b529c3752f9e4d80ef903a889cb78611407d Mon Sep 17 00:00:00 2001
From: yuni <hut@hut.pm>
Date: Tue, 11 Jun 2024 00:50:25 +0200
Subject: [PATCH] base `handle_wants_maxvelocity` on current orbital velocity

---
 src/actor.rs | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/actor.rs b/src/actor.rs
index 483baeb..755fd0d 100644
--- a/src/actor.rs
+++ b/src/actor.rs
@@ -31,7 +31,7 @@ impl Plugin for ActorPlugin {
                 update_physics_lifeforms,
                 update_power,
                 handle_wants_maxrotation,
-                handle_wants_maxvelocity,
+                handle_wants_maxvelocity.run_if(any_with_component::<WantsMaxVelocity>),
                 handle_wants_lookat.run_if(alive),
             ),
         );
@@ -548,11 +548,29 @@ fn handle_wants_maxrotation(
 /// Slows down NPC's movement until they reach their target velocity.
 fn handle_wants_maxvelocity(
     time: Res<Time>,
-    mut query: Query<(&mut LinearVelocity, &Engine, &WantsMaxVelocity)>,
+    mut query: Query<(
+        &Position,
+        &mut LinearVelocity,
+        &Engine,
+        &WantsMaxVelocity,
+        Option<&OrbitsJupiter>,
+    )>,
+    id2pos: Res<game::Id2Pos>,
 ) {
     let dt = time.delta_seconds();
-    for (mut v, engine, maxv) in &mut query {
-        let target_velocity = DVec3::splat(0.0);
+    let jupiter_pos: DVec3 = if let Some(jupiter_pos) = id2pos.0.get(cmd::ID_JUPITER) {
+        *jupiter_pos
+    } else {
+        warn!("Could not determine Jupiter's position");
+        DVec3::ZERO
+    };
+    for (pos, mut v, engine, maxv, orbits_jupiter) in &mut query {
+        let target_velocity = if orbits_jupiter.is_some() {
+            let relative_pos = pos.0 - jupiter_pos;
+            nature::orbital_velocity(relative_pos, nature::JUPITER_MASS)
+        } else {
+            DVec3::ZERO
+        };
         let relative_velocity = v.0 - target_velocity;
         let relative_speed = relative_velocity.length();