3 files changed, 76 insertions(+), 9 deletions(-)

M crates/unified/assets/config/world.wc.toml
M crates/unified/src/client/parts.rs
M crates/unified/src/server/player.rs

@@ 1,5 1,5 @@
 [world]
-gravity = 0.001
+gravity = 0.005
 spawn_parts_at = "Earth"
 spawn_parts_interval_secs = 10
 


@@ 9,5 9,5 @@ default_width = 50
 default_mass = 100
 
 [hearty]
-thrust = 50000
+thrust = 500000
 spawn_at = "Earth"

@@ 1,4 1,4 @@
-use crate::attachment::{JointOf, PartInShip, Peer, SnapOf, SnapOfJoint};
+use crate::attachment::{Joint, JointOf, Joints, PartInShip, Peer, SnapOf, SnapOfJoint};
 use crate::client::Me;
 use crate::client::colors::GREEN;
 use crate::client::key_input::AttachmentDebugRes;


@@ 89,7 89,8 @@ const ROTATION_SMOOTH: f32 = 0.1;
 
 fn on_part_click(
     ev: Trigger<Pointer<Pressed>>,
-    sprites: Query<(&Sprite, &Transform), Without<Me>>,
+    sprites: Query<(&Sprite, &Transform, &Joints), Without<Me>>,
+    joints: Query<&Joint, Without<Peer>>,
     mut drag: ResMut<DragResource>,
     mut commands: Commands,
 ) {


@@ 99,6 100,16 @@ fn on_part_click(
     let Ok(sprite) = sprites.get(ev.target()) else {
         return;
     };
+    // make sure it has at least 1 valid unpeered joint
+    let mut valid_peers = 0;
+    for joint in &**sprite.2 {
+        if joints.get(*joint).is_ok() {
+            valid_peers += 1;
+        }
+    }
+    if valid_peers == 0 {
+        return; // ignore
+    }
     let mut s = sprite.0.clone();
     s.color = Color::srgba(0.7, 0.7, 0.7, 1.0);
     commands.spawn((DragGhost, GhostTarget(sprite.1.rotation), *sprite.1, s));

@@ 8,20 8,24 @@ use bevy::prelude::*;
 use bevy_rapier2d::prelude::{ExternalForce, FixedJointBuilder, ImpulseJoint, Velocity};
 use bevy_replicon::prelude::FromClient;
 use std::f32::consts::PI;
-use crate::attachment::{Joint, JointOf, PartInShip, Peer, SnapOf, SnapOfJoint};
+use crate::attachment::{Joint, JointOf, Joints, PartInShip, Peer, SnapOf, SnapOfJoint};
 
 pub fn player_management_plugin(app: &mut App) {
     app.add_systems(
         Update,
-        (handle_new_players, player_thrust, magic_fuel_regen, dragging).in_set(PlayerInputSet),
+        (handle_new_players, player_thrust, magic_fuel_regen, (reprocess_reattached_parts, dragging).chain()).in_set(PlayerInputSet),
     );
 }
 
+#[derive(Component)]
+struct JointNeedsCreation(ImpulseJoint);
+
 fn dragging(
     mut events: EventReader<FromClient<DragRequestEvent>>,
-    mut parts: Query<(&mut Transform, Option<&PartInShip>, Entity, &mut Velocity), (With<Part>, Without<Joint>)>,
+    mut parts: Query<(&mut Transform, Option<&PartInShip>, Entity, &mut Velocity, &Joints), (With<Part>, Without<Joint>)>,
     snaps: Query<(&SnapOf, &SnapOfJoint)>,
     joints: Query<(&Joint, &JointOf, &Transform, Option<&Peer>, Entity)>,
+    peer: Query<&Peer>,
     clients: Query<&ConnectedNetworkEntity>,
     mut commands: Commands
 ) {


@@ 83,6 87,17 @@ fn dragging(
             // TODO - validate source_part?
 
             // great, we have a valid peering request
+
+            let mut did_disconnect = false;
+            // disconnect it, if it is connected
+            for joint in &**source_part.4 {
+                let Ok(joint_peer) = peer.get(*joint) else { continue };
+                did_disconnect = true;
+                commands.entity(*joint).remove::<Peer>();
+                commands.entity(joint_peer.0).remove::<Peer>();
+            }
+            commands.entity(source_part.2).remove::<ImpulseJoint>();
+
             // create the peering component...
             commands.entity(source_joint.4)
                 .insert(Peer(target_joint.4));


@@ 111,8 126,28 @@ fn dragging(
                 .local_basis1(target_joint.0.transform.rotation.to_euler(EulerRot::ZYX).0 + PI
                     - source_joint.0.transform.rotation.to_euler(EulerRot::ZYX).0);
 
-            commands.entity(source_part.2)
-                .insert(ImpulseJoint::new(target_part.2, joint));
+            commands.entity(source_part.2).remove::<ImpulseJoint>();
+            if !did_disconnect {
+                commands.entity(source_part.2)
+                    .insert(ImpulseJoint::new(target_part.2, joint));
+            } else {
+                // we disconnected this part this tick, and are performing a "reattachment"
+                // (dragging an already attached part from peering point A to peering point B)
+                
+                // If we're reattaching to a different part, rapier will ignore our new attachment
+                // as it will be seen as a mutation (removing and adding a component in the
+                // same tick is considered equivalent to mutation by Bevy). 
+                // As Rapier does not allow you to mutate the source/destination of a joint,
+                // the change will be outright ignored.
+                
+                // Since there is no (easy) way to get the real joint information back out of Rapier,
+                // or to force it to accept what it sees as invalid mutation,
+                // we need to delay the creation of the new joint by 1 tick so it's noticed by Rapier
+                // This component will be swapped out for a real ImpulseJoint on the next tick
+                // by `reprocess_reattached_parts` (in this file)
+                commands.entity(source_part.2)
+                    .insert(JointNeedsCreation(ImpulseJoint::new(target_part.2, joint)));
+            }
 
             teleport_to_translation = target_position.translation.xy();
             teleport_to_rotation = target_position.rotation * source_joint.0.transform.rotation.inverse() * Quat::from_rotation_z(PI);


@@ 121,6 156,14 @@ fn dragging(
         } else {
             warn!("blindly accepting non-attachment request, someone should change this eventually");
             warn!("dragging already attached entities may cause inconsistent behavior!!");
+            let source_part = parts.get(event.drag_target).unwrap();
+            // disconnect it, if it is connected
+            for joint in &**source_part.4 {
+                let Ok(joint_peer) = peer.get(*joint) else { continue };
+                commands.entity(*joint).remove::<Peer>();
+                commands.entity(joint_peer.0).remove::<Peer>();
+            }
+            commands.entity(source_part.2).remove::<ImpulseJoint>();
             teleport_to_translation = event.drag_to;
             teleport_to_rotation = event.set_rotation;
         }


@@ 136,6 179,19 @@ fn dragging(
     }
 }
 
+// LOGIC: **MUST** run BEFORE `dragging`
+fn reprocess_reattached_parts(
+    reattached: Query<(Entity, &JointNeedsCreation)>,
+    mut commands: Commands
+) {
+    for (e, j) in &reattached {
+        commands.entity(e)
+            .remove::<JointNeedsCreation>()
+            .insert(j.0);
+    }
+}
+
+
 fn handle_new_players(
     mut commands: Commands,
     q_new_clients: Query<Entity, Added<ConnectedGameEntity>>,