slow acceleration

src/main.rs

@@ -1,9 +1,9 @@
-#![allow(unused)]
+// #![allow(unused)]
 
 mod boid_mesh;
 mod boundary;
 
-use bevy::{color::palettes::tailwind, prelude::*, reflect::List, sprite::MaterialMesh2dBundle};
+use bevy::{color::palettes::tailwind, prelude::*, sprite::MaterialMesh2dBundle};
 use boid_mesh::BoidMesh;
 use rand::{Rng, SeedableRng};
 
@@ -15,8 +15,10 @@ fn main() {
         .add_systems(
             Update,
             (
+                build_local_cache,
                 (seperation, cohesion, alignment),
-                (accelerate, move_boids).chain(),
+                accelerate,
+                move_boids,
                 boundary::boid_border_teleport,
             )
                 .chain(),
@@ -51,7 +53,8 @@ struct BoidBundle {
     mesh: MaterialMesh2dBundle<ColorMaterial>,
     velocity: Velocity,
     boid: Boid,
-    cache: BoidAccelerationBundle,
+    accel_cache: BoidAccelerationBundle,
+    local_cache: LocalCache,
 }
 
 #[derive(Component, Default)]
@@ -80,11 +83,38 @@ fn build_local_cache(
         });
 }
 
-fn seperation(mut boids: Query<(Entity, &Transform, &mut SeperationAcceleration), With<Boid>>) {}
+fn seperation(
+    mut boids: Query<(&Transform, &LocalCache, &mut SeperationAcceleration), With<Boid>>,
+) {
+}
 
-fn cohesion(mut boids: Query<(Entity, &Transform, &mut CohesionAcceleration), With<Boid>>) {}
+fn cohesion(mut boids: Query<(&Transform, &LocalCache, &mut CohesionAcceleration), With<Boid>>) {}
 
-fn alignment(mut boids: Query<(Entity, &Transform, &mut AlignmentAcceleration), With<Boid>>) {}
+fn alignment(
+    mut boids: Query<(&Velocity, &LocalCache, &mut AlignmentAcceleration), With<Boid>>,
+    other_boids: Query<&Velocity, With<Boid>>,
+) {
+    const MAX_FORCE: f32 = 50.;
+
+    boids
+        .par_iter_mut()
+        .for_each(|(velocity, local, mut accel)| {
+            accel.0 = Vec2::ZERO;
+            let mut count = 0;
+            for other_velocity in other_boids.iter_many(&local.0[..]) {
+                accel.0 += other_velocity.0;
+
+                count += 1;
+            }
+
+            if count > 0 {
+                accel.0 /= count as f32;
+                accel.0 -= velocity.0;
+
+                accel.0 = accel.0.clamp_length_max(MAX_FORCE);
+            }
+        });
+}
 
 fn accelerate(
     mut boids: Query<
@@ -105,9 +135,12 @@ fn accelerate(
             vel.0 += coh.0 * time.delta_seconds();
             vel.0 += ali.0 * time.delta_seconds();
 
+            vel.0 *= 1.005;
+            vel.0 = vel.0.clamp_length_max(200.);
+
             sep.0 *= 0.;
-            sep.0 *= 0.;
-            sep.0 *= 0.;
+            coh.0 *= 0.;
+            ali.0 *= 0.;
         });
 }
 
@@ -137,7 +170,7 @@ fn setup(
     let lower_height = -half_height;
     let upper_height = half_height;
 
-    for i in 0..1000 {
+    for _ in 0..1000 {
         use std::f32::consts::TAU;
 
         let x = small_rng.gen_range(lower_width..=upper_width);