use std::{f32::consts::PI, time::Duration};
use bevy::{
animation::AnimationTargetId, color::palettes::css::WHITE, pbr::CascadeShadowConfigBuilder,
prelude::*,
};
use rand::{Rng, SeedableRng};
use rand_chacha::ChaCha8Rng;
const FOX_PATH: &str = "models/animated/Fox.glb";
fn main() {
App::new()
.insert_resource(AmbientLight {
color: Color::WHITE,
brightness: 2000.,
..default()
})
.add_plugins(DefaultPlugins)
.init_resource::<ParticleAssets>()
.init_resource::<FoxFeetTargets>()
.add_systems(Startup, setup)
.add_systems(Update, setup_scene_once_loaded)
.add_systems(Update, simulate_particles)
.add_observer(observe_on_step)
.run();
}
#[derive(Resource)]
struct SeededRng(ChaCha8Rng);
#[derive(Resource)]
struct Animations {
index: AnimationNodeIndex,
graph_handle: Handle<AnimationGraph>,
}
#[derive(Event, Reflect, Clone)]
struct OnStep;
fn observe_on_step(
trigger: Trigger<OnStep>,
particle: Res<ParticleAssets>,
mut commands: Commands,
transforms: Query<&GlobalTransform>,
mut seeded_rng: ResMut<SeededRng>,
) {
let translation = transforms.get(trigger.target()).unwrap().translation();
for _ in 0..14 {
let horizontal = seeded_rng.0.r#gen::<Dir2>() * seeded_rng.0.gen_range(8.0..12.0);
let vertical = seeded_rng.0.gen_range(0.0..4.0);
let size = seeded_rng.0.gen_range(0.2..1.0);
commands.spawn((
Particle {
lifetime_timer: Timer::from_seconds(
seeded_rng.0.gen_range(0.2..0.6),
TimerMode::Once,
),
size,
velocity: Vec3::new(horizontal.x, vertical, horizontal.y) * 10.0,
},
Mesh3d(particle.mesh.clone()),
MeshMaterial3d(particle.material.clone()),
Transform {
translation,
scale: Vec3::splat(size),
..Default::default()
},
));
}
}
fn setup(
mut commands: Commands,
asset_server: Res<AssetServer>,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
mut graphs: ResMut<Assets<AnimationGraph>>,
) {
let (graph, index) = AnimationGraph::from_clip(
asset_server.load(GltfAssetLabel::Animation(2).from_asset(FOX_PATH)),
);
let graph_handle = graphs.add(graph);
commands.insert_resource(Animations {
index,
graph_handle,
});
commands.spawn((
Camera3d::default(),
Transform::from_xyz(100.0, 100.0, 150.0).looking_at(Vec3::new(0.0, 20.0, 0.0), Vec3::Y),
));
commands.spawn((
Mesh3d(meshes.add(Plane3d::default().mesh().size(500000.0, 500000.0))),
MeshMaterial3d(materials.add(Color::srgb(0.3, 0.5, 0.3))),
));
commands.spawn((
Transform::from_rotation(Quat::from_euler(EulerRot::ZYX, 0.0, 1.0, -PI / 4.)),
DirectionalLight {
shadows_enabled: true,
..default()
},
CascadeShadowConfigBuilder {
first_cascade_far_bound: 200.0,
maximum_distance: 400.0,
..default()
}
.build(),
));
commands.spawn(SceneRoot(
asset_server.load(GltfAssetLabel::Scene(0).from_asset(FOX_PATH)),
));
let seeded_rng = ChaCha8Rng::seed_from_u64(19878367467712);
commands.insert_resource(SeededRng(seeded_rng));
}
fn setup_scene_once_loaded(
mut commands: Commands,
animations: Res<Animations>,
feet: Res<FoxFeetTargets>,
graphs: Res<Assets<AnimationGraph>>,
mut clips: ResMut<Assets<AnimationClip>>,
mut players: Query<(Entity, &mut AnimationPlayer), Added<AnimationPlayer>>,
) {
fn get_clip<'a>(
node: AnimationNodeIndex,
graph: &AnimationGraph,
clips: &'a mut Assets<AnimationClip>,
) -> &'a mut AnimationClip {
let node = graph.get(node).unwrap();
let clip = match &node.node_type {
AnimationNodeType::Clip(handle) => clips.get_mut(handle),
_ => unreachable!(),
};
clip.unwrap()
}
for (entity, mut player) in &mut players {
let graph = graphs.get(&animations.graph_handle).unwrap();
let running_animation = get_clip(animations.index, graph, &mut clips);
running_animation.add_event_to_target(feet.front_left, 0.625, OnStep);
running_animation.add_event_to_target(feet.front_right, 0.5, OnStep);
running_animation.add_event_to_target(feet.back_left, 0.0, OnStep);
running_animation.add_event_to_target(feet.back_right, 0.125, OnStep);
let mut transitions = AnimationTransitions::new();
transitions
.play(&mut player, animations.index, Duration::ZERO)
.repeat();
commands
.entity(entity)
.insert(AnimationGraphHandle(animations.graph_handle.clone()))
.insert(transitions);
}
}
fn simulate_particles(
mut commands: Commands,
mut query: Query<(Entity, &mut Transform, &mut Particle)>,
time: Res<Time>,
) {
for (entity, mut transform, mut particle) in &mut query {
if particle.lifetime_timer.tick(time.delta()).just_finished() {
commands.entity(entity).despawn();
return;
}
transform.translation += particle.velocity * time.delta_secs();
transform.scale = Vec3::splat(particle.size.lerp(0.0, particle.lifetime_timer.fraction()));
particle
.velocity
.smooth_nudge(&Vec3::ZERO, 4.0, time.delta_secs());
}
}
#[derive(Component)]
struct Particle {
lifetime_timer: Timer,
size: f32,
velocity: Vec3,
}
#[derive(Resource)]
struct ParticleAssets {
mesh: Handle<Mesh>,
material: Handle<StandardMaterial>,
}
impl FromWorld for ParticleAssets {
fn from_world(world: &mut World) -> Self {
Self {
mesh: world.add_asset::<Mesh>(Sphere::new(10.0)),
material: world.add_asset::<StandardMaterial>(StandardMaterial {
base_color: WHITE.into(),
..Default::default()
}),
}
}
}
#[derive(Resource)]
struct FoxFeetTargets {
front_right: AnimationTargetId,
front_left: AnimationTargetId,
back_left: AnimationTargetId,
back_right: AnimationTargetId,
}
impl Default for FoxFeetTargets {
fn default() -> Self {
let hip_node = ["root", "_rootJoint", "b_Root_00", "b_Hip_01"];
let front_left_foot = hip_node.iter().chain(
[
"b_Spine01_02",
"b_Spine02_03",
"b_LeftUpperArm_09",
"b_LeftForeArm_010",
"b_LeftHand_011",
]
.iter(),
);
let front_right_foot = hip_node.iter().chain(
[
"b_Spine01_02",
"b_Spine02_03",
"b_RightUpperArm_06",
"b_RightForeArm_07",
"b_RightHand_08",
]
.iter(),
);
let back_left_foot = hip_node.iter().chain(
[
"b_LeftLeg01_015",
"b_LeftLeg02_016",
"b_LeftFoot01_017",
"b_LeftFoot02_018",
]
.iter(),
);
let back_right_foot = hip_node.iter().chain(
[
"b_RightLeg01_019",
"b_RightLeg02_020",
"b_RightFoot01_021",
"b_RightFoot02_022",
]
.iter(),
);
Self {
front_left: AnimationTargetId::from_iter(front_left_foot),
front_right: AnimationTargetId::from_iter(front_right_foot),
back_left: AnimationTargetId::from_iter(back_left_foot),
back_right: AnimationTargetId::from_iter(back_right_foot),
}
}
}