From 6275a64d7c665c16f4af87e42e74018755df81d6 Mon Sep 17 00:00:00 2001
From: yuni <hut@hut.pm>
Date: Tue, 11 Jun 2024 03:29:26 +0200
Subject: [PATCH] ignore gravity when calculating g forces
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Because gravity is obviously not a force, just a ✨magical✨ property of
spacetime, conveyed by messenger particles called Higgs Bosons which act
as force carriers for this non-force.  Who made this up? :D
---
 src/actor.rs | 38 +++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/src/actor.rs b/src/actor.rs
index d6820e1..f83c529 100644
--- a/src/actor.rs
+++ b/src/actor.rs
@@ -30,6 +30,7 @@ impl Plugin for ActorPlugin {
             (
                 update_physics_lifeforms,
                 update_power,
+                handle_gravity,
                 handle_wants_maxrotation,
                 handle_wants_maxvelocity.run_if(any_with_component::<WantsMaxVelocity>),
                 handle_wants_lookat.run_if(alive),
@@ -44,7 +45,6 @@ impl Plugin for ActorPlugin {
         app.add_systems(
             Update,
             (
-                handle_gravity,
                 handle_input.run_if(in_control),
                 handle_collisions,
                 handle_damage,
@@ -52,16 +52,9 @@ impl Plugin for ActorPlugin {
         );
         app.add_systems(PostUpdate, (handle_vehicle_enter_exit,));
         app.add_event::<VehicleEnterExitEvent>();
-        app.insert_resource(GravityUpdateTimer(Timer::from_seconds(
-            1.0,
-            TimerMode::Repeating,
-        )));
     }
 }
 
-#[derive(Resource)]
-pub struct GravityUpdateTimer(Timer);
-
 #[derive(Copy, Clone)]
 pub enum DamageType {
     Unknown,
@@ -126,6 +119,7 @@ pub struct ExperiencesGForce {
     pub visual_effect_threshold: f32,
     pub visual_effect: f32,
     pub last_linear_velocity: DVec3,
+    pub gravitational_component: DVec3,
     pub ignore_gforce_seconds: f32,
 }
 impl Default for ExperiencesGForce {
@@ -135,7 +129,8 @@ impl Default for ExperiencesGForce {
             damage_threshold: 100.0,
             visual_effect_threshold: 20.0,
             visual_effect: 0.0,
-            last_linear_velocity: DVec3::splat(0.0),
+            last_linear_velocity: DVec3::ZERO,
+            gravitational_component: DVec3::ZERO,
             ignore_gforce_seconds: 0.01,
         }
     }
@@ -650,8 +645,10 @@ fn handle_gforce(
     let dt = time.delta_seconds();
     let factor = 1.0 / dt / nature::EARTH_GRAVITY;
     for (v, mut hp, mut gforce) in &mut q_actor {
-        gforce.gforce = factor * (v.0 - gforce.last_linear_velocity).length() as f32;
+        gforce.gforce = factor
+            * (v.0 - gforce.last_linear_velocity - gforce.gravitational_component).length() as f32;
         gforce.last_linear_velocity = v.0;
+        gforce.gravitational_component = DVec3::ZERO;
         if gforce.ignore_gforce_seconds > 0.0 {
             gforce.ignore_gforce_seconds -= dt;
             continue;
@@ -675,18 +672,25 @@ fn handle_gforce(
 
 fn handle_gravity(
     time: Res<Time>,
-    mut timer: ResMut<GravityUpdateTimer>,
-    mut q_pos: Query<(&Position, &mut LinearVelocity), With<OrbitsJupiter>>,
+    mut q_pos: Query<
+        (
+            &Position,
+            &mut LinearVelocity,
+            Option<&mut ExperiencesGForce>,
+        ),
+        With<OrbitsJupiter>,
+    >,
     jupiter_pos: Res<game::JupiterPos>,
 ) {
-    if !timer.0.tick(time.delta()).just_finished() {
-        return;
-    }
+    let dt = time.delta_seconds() as f64;
 
     // this assumes prograde orbits for every object
-    for (pos, mut v) in &mut q_pos {
+    for (pos, mut v, gforce_maybe) in &mut q_pos {
         let relative_pos = pos.0 - jupiter_pos.0;
-        let accel = nature::gravitational_acceleration(relative_pos, nature::JUPITER_MASS);
+        let accel = dt * nature::gravitational_acceleration(relative_pos, nature::JUPITER_MASS);
+        if let Some(mut gforce) = gforce_maybe {
+            gforce.gravitational_component += accel;
+        }
         v.0 += accel;
     }
 }