docs/bevy/examples/3d/meshlet.rs 4.6 K · 132 lines · raw · history

1 //! Meshlet rendering for dense high-poly scenes (experimental).
2
3 // Note: This example showcases the meshlet API, but is not the type of scene that would benefit from using meshlets.
4
5 use bevy::{
6 camera_controller::free_camera::{FreeCamera, FreeCameraPlugin},
7 light::{CascadeShadowConfigBuilder, DirectionalLightShadowMap},
8 pbr::experimental::meshlet::{MeshletMesh3d, MeshletPlugin},
9 prelude::*,
10 render::render_resource::AsBindGroup,
11 };
12 use std::f32::consts::PI;
13
14 const ASSET_URL: &str =
15 "https://github.com/bevyengine/bevy_asset_files/raw/6dccaef517bde74d1969734703709aead7211dbc/meshlet/bunny.meshlet_mesh";
16
17 fn main() {
18 App::new()
19 .insert_resource(DirectionalLightShadowMap { size: 4096 })
20 .add_plugins((
21 DefaultPlugins,
22 MeshletPlugin {
23 cluster_buffer_slots: 1 << 14,
24 },
25 MaterialPlugin::<MeshletDebugMaterial>::default(),
26 FreeCameraPlugin,
27 ))
28 .add_systems(Startup, setup)
29 .add_systems(Update, bunny_wiggler)
30 .run();
31 }
32
33 fn setup(
34 mut commands: Commands,
35 asset_server: Res<AssetServer>,
36 mut standard_materials: ResMut<Assets<StandardMaterial>>,
37 mut debug_materials: ResMut<Assets<MeshletDebugMaterial>>,
38 mut meshes: ResMut<Assets<Mesh>>,
39 ) {
40 commands.spawn((
41 Camera3d::default(),
42 Transform::from_translation(Vec3::new(1.8, 0.4, -0.1)).looking_at(Vec3::ZERO, Vec3::Y),
43 Msaa::Off,
44 EnvironmentMapLight {
45 diffuse_map: asset_server.load("environment_maps/pisa_diffuse_rgb9e5_zstd.ktx2"),
46 specular_map: asset_server.load("environment_maps/pisa_specular_rgb9e5_zstd.ktx2"),
47 intensity: 150.0,
48 ..default()
49 },
50 FreeCamera::default(),
51 ));
52
53 commands.spawn((
54 DirectionalLight {
55 illuminance: light_consts::lux::FULL_DAYLIGHT,
56 shadow_maps_enabled: true,
57 ..default()
58 },
59 CascadeShadowConfigBuilder {
60 num_cascades: 1,
61 maximum_distance: 15.0,
62 ..default()
63 }
64 .build(),
65 Transform::from_rotation(Quat::from_euler(EulerRot::ZYX, 0.0, PI * -0.15, PI * -0.15)),
66 ));
67
68 // A custom file format storing a [`bevy_mesh::Mesh`]
69 // that has been converted to a [`bevy_pbr::meshlet::MeshletMesh`]
70 // using [`bevy_pbr::meshlet::MeshletMesh::from_mesh`], which is
71 // a function only available when the `meshlet_processor` cargo feature is enabled.
72 let meshlet_mesh_handle = asset_server.load(ASSET_URL);
73 let debug_material = debug_materials.add(MeshletDebugMaterial::default());
74
75 for x in -2..=2 {
76 let mut bunny = commands.spawn((
77 MeshletMesh3d(meshlet_mesh_handle.clone()),
78 MeshMaterial3d(standard_materials.add(StandardMaterial {
79 base_color: match x {
80 -2 => Srgba::hex("#dc2626").unwrap().into(),
81 -1 => Srgba::hex("#ea580c").unwrap().into(),
82 0 => Srgba::hex("#facc15").unwrap().into(),
83 1 => Srgba::hex("#16a34a").unwrap().into(),
84 2 => Srgba::hex("#0284c7").unwrap().into(),
85 _ => unreachable!(),
86 },
87 perceptual_roughness: (x + 2) as f32 / 4.0,
88 ..default()
89 })),
90 Transform::default()
91 .with_scale(Vec3::splat(0.2))
92 .with_translation(Vec3::new(x as f32 / 2.0, 0.0, -0.3)),
93 ));
94 if x == 1 {
95 bunny.insert(BunnyWiggler);
96 }
97 }
98 for x in -2..=2 {
99 commands.spawn((
100 MeshletMesh3d(meshlet_mesh_handle.clone()),
101 MeshMaterial3d(debug_material.clone()),
102 Transform::default()
103 .with_scale(Vec3::splat(0.2))
104 .with_rotation(Quat::from_rotation_y(PI))
105 .with_translation(Vec3::new(x as f32 / 2.0, 0.0, 0.3)),
106 ));
107 }
108
109 commands.spawn((
110 Mesh3d(meshes.add(Plane3d::default().mesh().size(5.0, 5.0))),
111 MeshMaterial3d(standard_materials.add(StandardMaterial {
112 base_color: Color::WHITE,
113 perceptual_roughness: 1.0,
114 ..default()
115 })),
116 ));
117 }
118
119 #[derive(Component)]
120 struct BunnyWiggler;
121
122 fn bunny_wiggler(mut bunny: Query<&mut Transform, With<BunnyWiggler>>, time: Res<Time>) {
123 bunny.single_mut().as_deref_mut().unwrap().translation.z +=
124 ops::cos(time.elapsed_secs() * 10.0) * 0.003;
125 }
126
127 #[derive(Asset, TypePath, AsBindGroup, Clone, Default)]
128 struct MeshletDebugMaterial {
129 _dummy: (),
130 }
131
132 impl Material for MeshletDebugMaterial {}