fix: make bar face camera with rotation applied (#26)

examples/rotation.rs

@@ -0,0 +1,167 @@
+//! Example with multiple rotating meshes and a moving camera.
+//! Bars always face the camera.
+
+use std::f32::consts::PI;
+
+use bevy::app::App;
+use bevy::asset::Assets;
+use bevy::pbr::*;
+use bevy::prelude::*;
+use bevy::utils::default;
+use bevy::DefaultPlugins;
+use bevy_inspector_egui::quick::WorldInspectorPlugin;
+
+use bevy_health_bar3d::prelude::{
+    BarBundle, BarHeight, BarOffset, BarWidth, HealthBarPlugin, Percentage,
+};
+
+#[derive(Component, Reflect)]
+struct Health {
+    max: f32,
+    current: f32,
+}
+
+impl Percentage for Health {
+    fn value(&self) -> f32 {
+        self.current / self.max
+    }
+}
+
+#[derive(Component)]
+struct Jim;
+
+#[derive(Component)]
+struct Tom;
+
+fn main() {
+    App::new()
+        .register_type::<Health>()
+        .add_plugins((
+            DefaultPlugins,
+            WorldInspectorPlugin::new(),
+            HealthBarPlugin::<Health>::default(),
+        ))
+        .add_systems(Startup, setup)
+        .add_systems(Update, (rotate_camera, rotate_jim, rotate_tom))
+        .run();
+}
+
+const TREX_GLTF: &str = "../examples/assets/models/trex.gltf";
+
+fn setup(
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<StandardMaterial>>,
+    asset_server: Res<AssetServer>,
+) {
+    let gltf_path = |id: &str| format!("{TREX_GLTF}#{id}");
+
+    // Ground
+    commands.spawn(PbrBundle {
+        mesh: meshes.add(Mesh::from(shape::Plane {
+            size: 5.0,
+            subdivisions: 0,
+        })),
+        material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
+        ..default()
+    });
+
+    let scene = asset_server.load(gltf_path("Scene0"));
+
+    // T-Rex Jim
+    commands.spawn((
+        SceneBundle {
+            scene: scene.clone(),
+            transform: Transform {
+                translation: Vec3::new(-1., 0., 0.),
+                scale: Vec3::splat(0.04),
+                ..default()
+            },
+            ..default()
+        },
+        Health {
+            max: 10.,
+            current: 8.,
+        },
+        BarBundle::<Health> {
+            offset: BarOffset::new(18.),
+            height: BarHeight::Static(1.),
+            width: BarWidth::new(10.),
+            ..default()
+        },
+        Jim,
+        Name::new("Jim"),
+    ));
+
+    // T-Rex Tom
+    commands.spawn((
+        SceneBundle {
+            scene: scene.clone(),
+            transform: Transform {
+                translation: Vec3::new(1., 0.75, 0.),
+                scale: Vec3::splat(0.04),
+                ..default()
+            },
+            ..default()
+        },
+        Health {
+            max: 10.,
+            current: 3.,
+        },
+        BarBundle::<Health> {
+            // Have to locate it higher than Jim's so there is no clipping during rotation
+            offset: BarOffset::new(21.),
+            height: BarHeight::Static(1.),
+            width: BarWidth::new(10.),
+            ..default()
+        },
+        Tom,
+        Name::new("Tom"),
+    ));
+
+    // Light
+    commands.spawn(PointLightBundle {
+        transform: Transform::from_xyz(4.0, 8.0, 4.0),
+        point_light: PointLight {
+            intensity: 1500.0,
+            shadows_enabled: true,
+            ..default()
+        },
+        ..default()
+    });
+
+    // Camera
+    commands.spawn(Camera3dBundle {
+        transform: Transform::from_xyz(0., 3.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
+        ..default()
+    });
+}
+
+fn rotate_camera(
+    mut camera_query: Query<&mut Transform, With<Camera3d>>,
+    mut angle: Local<f32>,
+    time: Res<Time>,
+) {
+    let mut transform = camera_query.single_mut();
+    let mut target_angle = *angle + 10. * time.delta_seconds();
+
+    if target_angle > 360. {
+        target_angle = 0.;
+    }
+
+    transform.translation.x = 5. * target_angle.to_radians().cos();
+    transform.translation.z = 5. * target_angle.to_radians().sin();
+
+    *angle = target_angle;
+    *transform = transform.looking_at(Vec3::ZERO, Vec3::Y);
+}
+
+fn rotate_jim(mut jim_query: Query<&mut Transform, With<Jim>>, timer: Res<Time>) {
+    let mut transform = jim_query.single_mut();
+    transform.rotate_y(PI * timer.delta_seconds());
+}
+
+fn rotate_tom(mut tom_query: Query<&mut Transform, With<Tom>>, timer: Res<Time>) {
+    let mut transform = tom_query.single_mut();
+    transform.rotate_x(PI * timer.delta_seconds());
+}

src/plugin.rs

@@ -37,6 +37,7 @@ impl<T: Percentage + Component + TypePath> Plugin for HealthBarPlugin<T> {
 
         app.init_resource::<MeshHandles>()
             .init_resource::<ColorScheme<T>>()
+            .add_systems(PostUpdate, reset_rotation)
             .add_systems(Update, (spawn::<T>, remove::<T>, update::<T>));
     }
 }
@@ -168,3 +169,14 @@ fn remove<T: Percentage + Component>(
         commands.entity(bar_entity).despawn_recursive()
     });
 }
+
+fn reset_rotation(
+    mut bar_query: Query<(&Parent, &mut Transform), With<Handle<BarMaterial>>>,
+    q_transform: Query<&Transform, Without<Handle<BarMaterial>>>,
+) {
+    for (parent, mut transform) in bar_query.iter_mut() {
+        if let Ok(parent_transform) = q_transform.get(parent.get()) {
+            transform.rotation = parent_transform.rotation.inverse();
+        }
+    }
+}