depth.rs

use bevy::color::palettes;
use bevy::prelude::*;
use bevy_mod_billboard::prelude::*;
use bevy_mod_billboard::BillboardDepth;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(BillboardPlugin)
        .add_systems(Startup, (setup_billboard, setup_scene))
        .add_systems(Update, rotate_camera)
        .run();
}

const TEXT_SCALE: Vec3 = Vec3::splat(0.0085);

fn setup_billboard(mut commands: Commands, asset_server: Res<AssetServer>) {
    let fira_sans_regular_handle = asset_server.load("FiraSans-Regular.ttf");

    commands.spawn(BillboardTextBundle {
        transform: Transform::from_translation(Vec3::new(0., 0.5, 0.)).with_scale(TEXT_SCALE),
        text: Text::from_section(
            "depth enabled",
            TextStyle {
                font_size: 60.0,
                font: fira_sans_regular_handle.clone(),
                color: Color::WHITE,
            },
        )
        .with_justify(JustifyText::Center),
        ..default()
    });

    commands.spawn(BillboardTextBundle {
        transform: Transform::from_translation(Vec3::new(0., -0.5, 0.)).with_scale(TEXT_SCALE),
        text: Text::from_section(
            "depth disabled",
            TextStyle {
                font_size: 60.0,
                font: fira_sans_regular_handle.clone(),
                color: Color::WHITE,
            },
        )
        .with_justify(JustifyText::Center),
        billboard_depth: BillboardDepth(false),
        ..default()
    });
}

// Important bits are above, the code below is for camera, reference cube and rotation

#[derive(Component)]
pub struct CameraHolder;

fn setup_scene(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    commands
        .spawn((CameraHolder, Transform::IDENTITY, GlobalTransform::IDENTITY))
        .with_children(|parent| {
            parent.spawn(Camera3dBundle {
                transform: Transform::from_translation(Vec3::new(5., 0., 0.))
                    .looking_at(Vec3::ZERO, Vec3::Y),
                ..default()
            });
        });

    commands.spawn(PbrBundle {
        mesh: meshes.add(Cuboid::default()),
        material: materials.add(Color::Srgba(palettes::css::BEIGE)),
        transform: Transform::from_translation(Vec3::new(1., 0., 0.)),
        ..default()
    });
}

fn rotate_camera(mut camera: Query<&mut Transform, With<CameraHolder>>, time: Res<Time>) {
    let mut camera = camera.single_mut();

    camera.rotate_y(time.delta_seconds());
}