dropping objects exist now

src/drops.rs

@@ -0,0 +1,139 @@
+use bevy::{
+    prelude::*,
+    sprite::{MaterialMesh2dBundle, Mesh2dHandle},
+    utils::HashSet,
+};
+use bevy_rand::prelude::*;
+use bevy_rapier2d::prelude::*;
+use rand::Rng;
+
+use crate::{player::Player, scene::SceneObj, METER};
+
+#[derive(Component)]
+struct SpawnTimer(pub Timer);
+
+#[derive(Component)]
+struct DroppedCrate;
+
+#[derive(Debug, Event)]
+struct CrateDropEvent {
+    pos: f32,
+}
+
+pub fn spawner_plugin(app: &mut App) {
+    app.add_plugins(EntropyPlugin::<WyRand>::default())
+        .add_event::<CrateDropEvent>()
+        .add_event::<CrateCollision>()
+        .add_systems(Startup, add_timer)
+        .add_systems(
+            Update,
+            (drop_crates, do_drop, crate_collisions, delete_on_env_coll),
+        );
+}
+
+fn add_timer(mut commands: Commands) {
+    commands.spawn(SpawnTimer(Timer::from_seconds(2., TimerMode::Repeating)));
+}
+
+fn drop_crates(
+    mut ev_drop: EventWriter<CrateDropEvent>,
+    mut rng: ResMut<GlobalEntropy<WyRand>>,
+    mut spawn_timer: Query<&mut SpawnTimer>,
+    time: Res<Time>,
+) {
+    let mut timer = spawn_timer.single_mut();
+
+    if timer.0.tick(time.delta()).finished() {
+        ev_drop.send(CrateDropEvent {
+            pos: rng.gen_range(-7f32..7f32),
+        });
+    }
+}
+
+fn do_drop(
+    mut ev_drop: EventReader<CrateDropEvent>,
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<ColorMaterial>>,
+) {
+    let rect = Mesh2dHandle(meshes.add(Rectangle::new(1. * METER, 1. * METER)));
+    for ev in ev_drop.read() {
+        println!("ev: {ev:?}");
+        commands
+            .spawn(DroppedCrate)
+            .insert(MaterialMesh2dBundle {
+                mesh: rect.clone(),
+                material: materials.add(Color::rgb(0.9, 0.8, 0.2)),
+                transform: Transform::from_xyz(ev.pos * METER, 12. * METER, 0.),
+                ..default()
+            })
+            .insert(ActiveEvents::COLLISION_EVENTS)
+            .insert((
+                RigidBody::Dynamic,
+                Collider::cuboid(0.5 * METER, 0.5 * METER),
+            ));
+    }
+}
+
+#[derive(Event)]
+struct CrateCollision {
+    coll_crate: Entity,
+    with: CollisionType,
+}
+
+enum CollisionType {
+    Player(Entity),
+    Scene(Entity),
+}
+
+fn crate_collisions(
+    mut player: Query<Entity, With<Player>>,
+    mut ev_colls: EventWriter<CrateCollision>,
+    drops: Query<Entity, With<DroppedCrate>>,
+    scene_objs: Query<Entity, With<SceneObj>>,
+    mut collision_events: EventReader<CollisionEvent>,
+) {
+    let p = player.single_mut();
+    let crates = drops.iter().collect::<HashSet<_>>();
+    let scene_objs = scene_objs.iter().collect::<HashSet<_>>();
+    for collision_event in collision_events.read() {
+        match collision_event {
+            CollisionEvent::Started(e1, e2, _) if crates.contains(e1) || crates.contains(e2) => {
+                let (coll_type, crate_) = if scene_objs.contains(e1) {
+                    (CollisionType::Scene(*e1), e2)
+                } else if scene_objs.contains(e2) {
+                    (CollisionType::Scene(*e2), e1)
+                } else if *e2 == p {
+                    (CollisionType::Player(*e2), e1)
+                } else if *e1 == p {
+                    (CollisionType::Player(*e1), e2)
+                } else if crates.contains(e1) && crates.contains(e2) {
+                    continue;
+                } else {
+                    // there can't be anything else to collide with,
+                    // only either scene objects or the player
+                    eprintln!("e1: {e1:?}, e2: {e2:?}");
+                    unreachable!()
+                };
+                ev_colls.send(CrateCollision {
+                    coll_crate: *crate_,
+                    with: coll_type,
+                });
+            }
+            _ => {}
+        }
+    }
+}
+
+fn delete_on_env_coll(mut ev_colls: EventReader<CrateCollision>, mut commands: Commands) {
+    for CrateCollision { coll_crate, with } in ev_colls.read() {
+        if let CollisionType::Player(_) = with {
+            continue;
+        }
+        // let CollisionType::Scene(obj) = with else {
+        //     unreachable!()
+        // };
+
+        commands.entity(*coll_crate).despawn();
+    }
+}

src/main.rs

@@ -3,14 +3,23 @@ use bevy::{
     sprite::{MaterialMesh2dBundle, Mesh2dHandle},
 };
 use bevy_rapier2d::prelude::*;
+use drops::spawner_plugin;
 const METER: f32 = 48.;
 
 fn main() {
+    let mut rapier_config = RapierConfiguration::new(METER * 2.5);
+    rapier_config.timestep_mode = TimestepMode::Variable {
+        max_dt: 1.0 / 60.0,
+        time_scale: 1.0,
+        substeps: 4,
+    };
     App::new()
         .add_plugins(DefaultPlugins)
-        .insert_resource(RapierConfiguration::new(METER * 2.5))
+        // this does things with gravity
+        .insert_resource(rapier_config)
         .add_plugins(RapierPhysicsPlugin::<NoUserData>::pixels_per_meter(METER))
         .add_plugins(RapierDebugRenderPlugin::default())
+        .add_plugins((spawner_plugin))
         .add_systems(Startup, (scene::setup_scene, setup_cam, player::add_player))
         .add_systems(
             Update,
@@ -26,5 +35,6 @@ fn setup_cam(mut commands: Commands) {
     });
 }
 
+mod drops;
 mod player;
 mod scene;

src/player.rs

@@ -91,7 +91,8 @@ pub fn move_player(
 
         if kb_input.pressed(KeyCode::KeyW) && player.grounded {
             moved = true;
-            *vel = Velocity::linear(Vec2::new(0., 9. * METER));
+            *vel = Velocity::linear(Vec2::new(0.,  9. * METER));
+            // *vel = Velocity::linear(Vec2::new(0., 9.81 * METER));
         }
 
         if moved {