swarms, but doesn't flock

src/lib.rs

@@ -2,11 +2,14 @@ use argh::FromArgs;
 use bevy::prelude::*;
 
 // toid
-const SPEED: f32 = 1.0;
+const SPEED: f32 = 10.0;
 const SPEED_DIFF_RANGE: f32 = 0.08; // +/- 8%
 
 // how far from origin before really wanting to come back
-const RADIUS: f32 = 100.0;
+const RADIUS: f32 = 800.0;
+
+// how close to try to stay to your buddies
+const BUDDY_RADIUS: f32 = 15.0;
 
 const MIN_ALTITUDE: f32 = 1.5;
 
@@ -45,8 +48,12 @@ pub fn turkey_time(
     let speed = SPEED + (SPEED * speed_diff);
     let vel = unit_vec(r) * speed;
     let buddies = r.gen_range(6..=8);
+    let spatial_bundle = SpatialBundle {
+        transform: Transform::from_xyz(0.0, MIN_ALTITUDE + 0.1, 0.0),
+        ..Default::default()
+    };
     commands
-        .spawn(SpatialBundle::default())
+        .spawn(spatial_bundle)
         .insert((Velocity(vel), Buddies::default(), Toid { speed, buddies }))
         .with_children(|t| {
             t.spawn(SceneBundle {
@@ -96,21 +103,30 @@ pub fn update_vel(
     let dt = time.delta_seconds();
     for (xform, mut vel, toid) in toids.iter_mut() {
         let speed = toid.speed;
-        let mut dir = xform.forward();
+        let mut dir = vel.normalize();
         let pos = xform.translation;
 
         // nudge up if too low
         if pos.y < MIN_ALTITUDE {
             let dh = MIN_ALTITUDE - pos.y;
-            let pct = (dh / MIN_ALTITUDE).min(1.0);
-            let up = Quat::from_rotation_arc(dir, Vec3::Y);
-            let rot = xform.rotation.slerp(up, pct);
+            let pct = (dh / MIN_ALTITUDE).min(1.0).powi(2);
+            let rot = Quat::from_rotation_arc(dir, Vec3::Y);
+            let (axis, ang) = rot.to_axis_angle();
+            let rot = Quat::from_axis_angle(axis, ang * pct).normalize();
             dir = rot.mul_vec3(dir);
         }
 
         // nudge toward origin if too far
-        let dist = pos.length();
-
+        {
+            let dist = pos.length();
+            let toward_origin = -pos.normalize();
+            let forward = dir.normalize();
+            let rot = Quat::from_rotation_arc(forward, toward_origin);
+            let pct = (dist / RADIUS).min(1.0);
+            let (axis, ang) = rot.to_axis_angle();
+            let rot = Quat::from_axis_angle(axis, ang * pct).normalize();
+            dir = rot.mul_vec3(dir);
+        }
         // find buddies and orient: point more towards further-away buddies
 
         **vel = dir * speed;

src/main.rs

@@ -15,7 +15,7 @@ fn main() {
             Update,
             (
                 update_vel,
-                add_gizmos,
+                //add_gizmos,
                 update_pos,
                 update_buddies,
                 rotate_camera,
@@ -37,7 +37,7 @@ fn setup(
     let rand = &mut rand::thread_rng();
 
     commands.spawn(Camera3dBundle {
-        transform: Transform::from_xyz(0., 3.5, 10.).looking_at(Vec3::ZERO, Vec3::Y),
+        transform: Transform::from_xyz(0., 3.5, 40.).looking_at(Vec3::new(0.0, 10.0, 0.0), Vec3::Y),
         ..default()
     });
     // plane