bevy_hanabi 0.18.0

//! Lifetime
//!
//! An example demonstrating the effect of the particle's lifetime. The example
//! spawns 3 effect instances, which emit a burst of particles every 3 seconds.
//! Each effect has a different particle lifetime:
//! - The left effect has a lifetime of 12 seconds, much longer than the spawn
//!   rate. Multiple bursts of particles are alive at the same time.
//! - The center effect has a lifetime of 3 seconds, exactly the spawn rate. As
//!   soon as particles die, a new burst spawns some more.
//! - The right effect has a lifetime of 0.75 seconds. Particle die very
//!   quickly, and during 2.25 seconds there's no particle, until the next burst
//!   spawns some more.

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

mod utils;
use utils::*;

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

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

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 * 180.),
        Camera3d::default(),
        Tonemapping::None,
    ));

    commands.spawn(DirectionalLight {
        color: Color::WHITE,
        // Crank the illuminance way (too) high to make the reference cube clearly visible
        illuminance: 100000.,
        shadows_enabled: false,
        ..Default::default()
    });

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

    let lifetime1 = 12.;
    let lifetime2 = 3.;
    let lifetime3 = 0.75;
    let period = 3.;

    let mut gradient1 = bevy_hanabi::Gradient::new();
    gradient1.add_key(0.0, Vec4::new(1.0, 0.0, 0.0, 1.0));
    gradient1.add_key(0.25, Vec4::new(1.0, 1.0, 0.0, 1.0));
    gradient1.add_key(0.5, Vec4::new(0.0, 1.0, 0.0, 1.0));
    gradient1.add_key(0.75, Vec4::new(0.0, 1.0, 1.0, 1.0));
    gradient1.add_key(1.0, Vec4::ONE);

    let writer1 = ExprWriter::new();
    let age1 = writer1.lit(0.).expr();
    let init_age1 = SetAttributeModifier::new(Attribute::AGE, age1);
    let lifetime1 = writer1.lit(lifetime1).expr();
    let init_lifetime1 = SetAttributeModifier::new(Attribute::LIFETIME, lifetime1);
    let init_pos1 = SetPositionSphereModifier {
        center: writer1.lit(Vec3::ZERO).expr(),
        radius: writer1.lit(5.).expr(),
        dimension: ShapeDimension::Volume,
    };
    let init_vel1 = SetVelocitySphereModifier {
        center: writer1.lit(Vec3::ZERO).expr(),
        speed: writer1.lit(2.).expr(),
    };
    let effect1 = effects.add(
        EffectAsset::new(
            512,
            SpawnerSettings::burst(50.0.into(), period.into()),
            writer1.finish(),
        )
        .with_name("emit:burst")
        .init(init_pos1)
        .init(init_vel1)
        .init(init_age1)
        .init(init_lifetime1)
        .render(ColorOverLifetimeModifier::new(gradient1)),
    );

    commands
        .spawn((
            Name::new("burst 12s"),
            ParticleEffect::new(effect1),
            Transform::from_translation(Vec3::new(-50., 0., 0.)),
        ))
        .with_children(|p| {
            // Reference cube to visualize the emit origin
            p.spawn((
                Mesh3d(cube.clone()),
                MeshMaterial3d(mat.clone()),
                Name::new("source"),
            ));
        });

    let mut gradient2 = bevy_hanabi::Gradient::new();
    gradient2.add_key(0.0, Vec4::new(1.0, 0.0, 0.0, 1.0));
    gradient2.add_key(1.0, Vec4::new(1.0, 1.0, 0.0, 1.0));

    let writer2 = ExprWriter::new();
    let age2 = writer2.lit(0.).expr();
    let init_age2 = SetAttributeModifier::new(Attribute::AGE, age2);
    let lifetime2 = writer2.lit(lifetime2).expr();
    let init_lifetime2 = SetAttributeModifier::new(Attribute::LIFETIME, lifetime2);
    let init_pos2 = SetPositionSphereModifier {
        center: writer2.lit(Vec3::ZERO).expr(),
        radius: writer2.lit(5.).expr(),
        dimension: ShapeDimension::Volume,
    };
    let init_vel2 = SetVelocitySphereModifier {
        center: writer2.lit(Vec3::ZERO).expr(),
        speed: writer2.lit(2.).expr(),
    };
    let effect2 = effects.add(
        EffectAsset::new(
            512,
            SpawnerSettings::burst(50.0.into(), period.into()),
            writer2.finish(),
        )
        .with_name("emit:burst")
        .init(init_pos2)
        .init(init_vel2)
        .init(init_age2)
        .init(init_lifetime2)
        .render(ColorOverLifetimeModifier::new(gradient2)),
    );

    commands
        .spawn((
            Name::new("burst 3s"),
            ParticleEffect::new(effect2),
            Transform::from_translation(Vec3::new(0., 0., 0.)),
        ))
        .with_children(|p| {
            // Reference cube to visualize the emit origin
            p.spawn((
                Mesh3d(cube.clone()),
                MeshMaterial3d(mat.clone()),
                Name::new("source"),
            ));
        });

    let mut gradient3 = bevy_hanabi::Gradient::new();
    gradient3.add_key(0.0, Vec4::new(1.0, 0.0, 0.0, 1.0));
    gradient3.add_key(1.0, Vec4::new(0.75, 0.25, 0.0, 1.0));

    let writer3 = ExprWriter::new();
    let age3 = writer3.lit(0.).expr();
    let init_age3 = SetAttributeModifier::new(Attribute::AGE, age3);
    let lifetime3 = writer3.lit(lifetime3).expr();
    let init_lifetime3 = SetAttributeModifier::new(Attribute::LIFETIME, lifetime3);
    let init_pos3 = SetPositionSphereModifier {
        center: writer3.lit(Vec3::ZERO).expr(),
        radius: writer3.lit(5.).expr(),
        dimension: ShapeDimension::Volume,
    };
    let init_vel3 = SetVelocitySphereModifier {
        center: writer3.lit(Vec3::ZERO).expr(),
        speed: writer3.lit(2.).expr(),
    };
    let effect3 = effects.add(
        EffectAsset::new(
            512,
            SpawnerSettings::burst(50.0.into(), period.into()),
            writer3.finish(),
        )
        .with_name("emit:burst")
        .init(init_pos3)
        .init(init_vel3)
        .init(init_age3)
        .init(init_lifetime3)
        .render(ColorOverLifetimeModifier::new(gradient3)),
    );

    commands
        .spawn((
            Name::new("burst 0.75s"),
            ParticleEffect::new(effect3),
            Transform::from_translation(Vec3::new(50., 0., 0.)),
        ))
        .with_children(|p| {
            // Reference cube to visualize the emit origin
            p.spawn((
                Mesh3d(cube.clone()),
                MeshMaterial3d(mat.clone()),
                Name::new("source"),
            ));
        });
}