light_gizmos.rs

//! This example demonstrates how to visualize lights properties through the gizmo API.

use std::f32::consts::{FRAC_PI_2, PI};

use bevy::{
    color::palettes::css::{DARK_CYAN, GOLD, GRAY, PURPLE},
    prelude::*,
};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .add_systems(Update, rotate_camera)
        .add_systems(Update, update_config)
        .run();
}

#[derive(Component)]
struct GizmoColorText;

fn gizmo_color_text(config: &LightGizmoConfigGroup) -> String {
    match config.color {
        LightGizmoColor::Manual(color) => format!("Manual {}", Srgba::from(color).to_hex()),
        LightGizmoColor::Varied => "Random from entity".to_owned(),
        LightGizmoColor::MatchLightColor => "Match light color".to_owned(),
        LightGizmoColor::ByLightType => {
            format!(
                "Point {}, Spot {}, Directional {}",
                Srgba::from(config.point_light_color).to_hex(),
                Srgba::from(config.spot_light_color).to_hex(),
                Srgba::from(config.directional_light_color).to_hex()
            )
        }
    }
}

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
    mut config_store: ResMut<GizmoConfigStore>,
) {
    // Circular base.
    commands.spawn((
        Mesh3d(meshes.add(Circle::new(4.0))),
        MeshMaterial3d(materials.add(Color::WHITE)),
        Transform::from_rotation(Quat::from_rotation_x(-FRAC_PI_2)),
    ));

    // Cubes.
    {
        let mesh = meshes.add(Cuboid::new(1.0, 1.0, 1.0));
        let material = materials.add(Color::srgb_u8(124, 144, 255));
        for x in [-2.0, 0.0, 2.0] {
            commands.spawn((
                Mesh3d(mesh.clone()),
                MeshMaterial3d(material.clone()),
                Transform::from_xyz(x, 0.5, 0.0),
            ));
        }
    }

    // Lights.
    {
        commands.spawn((
            PointLight {
                shadows_enabled: true,
                range: 2.0,
                color: DARK_CYAN.into(),
                ..default()
            },
            Transform::from_xyz(0.0, 1.5, 0.0),
        ));
        commands.spawn((
            SpotLight {
                shadows_enabled: true,
                range: 3.5,
                color: PURPLE.into(),
                outer_angle: PI / 4.0,
                inner_angle: PI / 4.0 * 0.8,
                ..default()
            },
            Transform::from_xyz(4.0, 2.0, 0.0).looking_at(Vec3::X * 1.5, Vec3::Y),
        ));
        commands.spawn((
            DirectionalLight {
                color: GOLD.into(),
                illuminance: DirectionalLight::default().illuminance * 0.05,
                shadows_enabled: true,
                ..default()
            },
            Transform::from_xyz(-4.0, 2.0, 0.0).looking_at(Vec3::NEG_X * 1.5, Vec3::Y),
        ));
    }

    // Camera.
    commands.spawn((
        Camera3d::default(),
        Transform::from_xyz(-2.5, 4.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));

    // Example instructions and gizmo config.
    {
        commands.spawn((
            Text::new(
                "Press 'D' to toggle drawing gizmos on top of everything else in the scene\n\
            Hold 'Left' or 'Right' to change the line width of the gizmos\n\
            Press 'A' to toggle drawing of the light gizmos\n\
            Press 'C' to cycle between the light gizmos coloring modes",
            ),
            Node {
                position_type: PositionType::Absolute,
                top: Val::Px(12.0),
                left: Val::Px(12.0),
                ..default()
            },
        ));

        let (_, light_config) = config_store.config_mut::<LightGizmoConfigGroup>();
        light_config.draw_all = true;
        light_config.color = LightGizmoColor::MatchLightColor;

        commands
            .spawn((
                Text::new("Gizmo color mode: "),
                GizmoColorText,
                Node {
                    position_type: PositionType::Absolute,
                    bottom: Val::Px(12.0),
                    left: Val::Px(12.0),
                    ..default()
                },
            ))
            .with_child(TextSpan(gizmo_color_text(light_config)));
    }
}

fn rotate_camera(mut transform: Single<&mut Transform, With<Camera>>, time: Res<Time>) {
    transform.rotate_around(Vec3::ZERO, Quat::from_rotation_y(time.delta_secs() / 2.));
}

fn update_config(
    mut config_store: ResMut<GizmoConfigStore>,
    keyboard: Res<ButtonInput<KeyCode>>,
    time: Res<Time>,
    color_text_query: Single<Entity, With<GizmoColorText>>,
    mut writer: TextUiWriter,
) {
    if keyboard.just_pressed(KeyCode::KeyD) {
        for (_, config, _) in config_store.iter_mut() {
            config.depth_bias = if config.depth_bias == 0. { -1. } else { 0. };
        }
    }

    let (config, light_config) = config_store.config_mut::<LightGizmoConfigGroup>();
    if keyboard.pressed(KeyCode::ArrowRight) {
        config.line_width += 5. * time.delta_secs();
        config.line_width = config.line_width.clamp(0., 50.);
    }
    if keyboard.pressed(KeyCode::ArrowLeft) {
        config.line_width -= 5. * time.delta_secs();
        config.line_width = config.line_width.clamp(0., 50.);
    }
    if keyboard.just_pressed(KeyCode::KeyA) {
        config.enabled ^= true;
    }
    if keyboard.just_pressed(KeyCode::KeyC) {
        light_config.color = match light_config.color {
            LightGizmoColor::Manual(_) => LightGizmoColor::Varied,
            LightGizmoColor::Varied => LightGizmoColor::MatchLightColor,
            LightGizmoColor::MatchLightColor => LightGizmoColor::ByLightType,
            LightGizmoColor::ByLightType => LightGizmoColor::Manual(GRAY.into()),
        };
        *writer.text(*color_text_query, 1) = gizmo_color_text(light_config);
    }
}