bevy_hanabi 0.18.0

//! This example demonstrates the various position initializing modifiers.
//!
//! The example spawns a single burst of particles according to several position
//! modifiers, with an infinite lifetime, and without any velocity nor
//! acceleration. This allows visualizing the distribution of particles on
//! spawn.

use std::f32::consts::PI;

use bevy::{core_pipeline::tonemapping::Tonemapping, prelude::*};
use bevy_hanabi::prelude::*;

mod utils;
use utils::*;

const DEMO_DESC: &str = include_str!("init.txt");

#[derive(Component)]
struct RotateSpeed(pub f32);

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let app_exit = utils::DemoApp::new("init")
        .with_desc(DEMO_DESC)
        .with_desc_position(DescPosition::BottomRow)
        .build()
        .add_systems(Startup, setup)
        .add_systems(Update, rotate_effect)
        .run();
    app_exit.into_result()
}

const COLOR: Vec4 = Vec4::new(0.7, 0.7, 1.0, 1.0);
const SIZE: Vec3 = Vec3::splat(0.1);

fn base_effect<M, F>(name: impl Into<String>, mut make_modifier: F) -> EffectAsset
where
    M: Modifier + Send + Sync + 'static,
    F: FnMut(&ExprWriter) -> M,
{
    let writer = ExprWriter::new();

    let init = make_modifier(&writer);

    EffectAsset::new(32768, SpawnerSettings::once(COUNT.into()), writer.finish())
        .with_name(name)
        // Disable motion integration; in this demo particles don't move. This silences some warning
        // about missing the VELOCITY attribute.
        .with_motion_integration(MotionIntegration::None)
        .with_simulation_space(SimulationSpace::Local)
        .init(init)
        .render(OrientModifier::new(OrientMode::FaceCameraPosition))
        .render(SetColorModifier::new(COLOR))
        .render(SetSizeModifier { size: SIZE.into() })
}

fn spawn_effect(
    commands: &mut Commands,
    name: String,
    speed: f32,
    transform: Transform,
    effect: Handle<EffectAsset>,
    mesh: Handle<Mesh>,
    material: Handle<StandardMaterial>,
) {
    commands
        .spawn((
            transform,
            Name::new(format!("{}_parent", name)),
            Visibility::default(),
        ))
        .with_children(|p| {
            p.spawn((
                Name::new(name),
                ParticleEffect::new(effect),
                RotateSpeed(speed),
            ))
            .with_children(|p| {
                // Reference cube to visualize the emit origin
                p.spawn((Mesh3d(mesh), MeshMaterial3d(material)));
            });
        });
}

const COUNT: f32 = 500_f32;

fn setup(
    mut commands: Commands,
    mut effects: ResMut<Assets<EffectAsset>>,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    commands.spawn((
        Transform::from_translation(Vec3::Z * 50.),
        Camera3d::default(),
        Tonemapping::None,
    ));

    commands.spawn(DirectionalLight {
        color: Color::WHITE,
        // Crank the illuminance way (too) high to make the reference cube clearly visible
        illuminance: 1000.,
        shadows_enabled: false,
        ..Default::default()
    });

    let cube = meshes.add(Cuboid {
        half_size: Vec3::splat(0.5),
    });
    let mat = materials.add(utils::COLOR_PURPLE);

    spawn_effect(
        &mut commands,
        "SetPositionCircleModifier".to_string(),
        3.,
        Transform::from_translation(Vec3::new(-20., 0., 0.)),
        effects.add(base_effect("SetPositionCircleModifier", |writer| {
            SetPositionCircleModifier {
                center: writer.lit(Vec3::ZERO).expr(),
                axis: writer.lit(Vec3::Z).expr(),
                radius: writer.lit(5.).expr(),
                dimension: ShapeDimension::Volume,
            }
        })),
        cube.clone(),
        mat.clone(),
    );

    spawn_effect(
        &mut commands,
        "SetPositionSphereModifier".to_string(),
        3.,
        Transform::from_translation(Vec3::new(0., 0., 0.)),
        effects.add(base_effect("SetPositionSphereModifier", |writer| {
            SetPositionSphereModifier {
                center: writer.lit(Vec3::ZERO).expr(),
                radius: writer.lit(5.).expr(),
                dimension: ShapeDimension::Volume,
            }
        })),
        cube.clone(),
        mat.clone(),
    );

    spawn_effect(
        &mut commands,
        "SetPositionCone3dModifier".to_string(),
        3.,
        Transform::from_translation(Vec3::new(20., 0., 0.)),
        effects.add(base_effect("SetPositionCone3dModifier", |writer| {
            SetPositionCone3dModifier {
                height: writer.lit(10.).expr(),
                base_radius: writer.lit(1.).expr(),
                top_radius: writer.lit(4.).expr(),
                dimension: ShapeDimension::Volume,
            }
        })),
        cube.clone(),
        mat.clone(),
    );
}

fn rotate_effect(time: Res<Time>, mut query: Query<(&RotateSpeed, &mut Transform)>) {
    for (speed, mut transform) in &mut query {
        let a = (time.elapsed_secs() * 0.1 * speed.0) * PI;
        *transform = Transform::from_rotation(Quat::from_rotation_y(a));
    }
}