Bevy 0.20 — PBR Materials

When to use this skill

• Texturing a mesh with the built-in physically based shader.
• Writing a custom Material (stylised shading, dissolve, world-space effects).
• Compiler error: no field shadows_enabled on a light (renamed in 0.19).
• Shader error: #import or #ifdef not recognised (naga_oil is gone in 0.20).
• Translucent glass renders flat (screen-space transmission is opt-in in 0.20).
• Handle<StandardMaterial> from a glTF sub-asset fails to load (needs /std since 0.19).

Canonical pattern — StandardMaterial

use bevy::pbr::ContactShadows;
use bevy::prelude::*;

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

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    let mesh = meshes.add(Cuboid::new(1.0, 1.0, 1.0));
    let material = materials.add(StandardMaterial {
        base_color: Color::srgb(0.8, 0.3, 0.2),
        perceptual_roughness: 0.4,
        metallic: 0.1,
        ..default()
    });

    commands.spawn((
        Mesh3d(mesh),
        MeshMaterial3d(material),
        Transform::from_xyz(0.0, 0.5, 0.0),
    ));

    commands.spawn((
        Camera3d::default(),
        // Screen-space contact shadows (0.19+). Requires the depth prepass,
        // which `ContactShadows` adds as a required component.
        ContactShadows::default(),
        Transform::from_xyz(0.0, 2.0, 4.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));

    commands.spawn((
        DirectionalLight {
            // 0.19 renamed `shadows_enabled` to `shadow_maps_enabled`.
            shadow_maps_enabled: true,
            contact_shadows_enabled: true,
            ..default()
        },
        Transform::from_xyz(2.0, 4.0, 2.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));
}

Custom Material — 0.20 shape

use bevy::prelude::*;
use bevy::render::render_resource::AsBindGroup;
use bevy::shader::ShaderRef;

#[derive(Asset, AsBindGroup, TypePath, Debug, Clone)]
struct TintMaterial {
    #[uniform(0)]
    tint: LinearRgba,
}

impl Material for TintMaterial {
    // 0.20: shaders are WESL. Use the `.wesl` extension for anything with imports.
    fn fragment_shader() -> ShaderRef {
        "shaders/tint.wesl".into()
    }
}

assets/shaders/tint.wesl:

import bevy_pbr::render::forward_io::VertexOutput;

@group(2) @binding(0) var<uniform> tint: vec4<f32>;

@fragment
fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
    return tint;
}

Full Material trait reference, AsBindGroup attributes and WESL translation rules: references/custom-material.md.

Topics

Gotchas

0.19 → 0.20

• Shaders are WESL. naga_oil is gone. #import bevy_pbr::forward_io::VertexOutput becomes import bevy_pbr::render::forward_io::VertexOutput; (semicolon, module path mirrors the crate file path). #ifdef X ... #endif becomes @if(X) on a declaration. #{MATERIAL_BIND_GROUP} becomes constants::MATERIAL_BIND_GROUP. #define_import_path is gone. Rename files .wgsl → .wesl; plain WGSL with no directives still loads. GLSL and the shader_format_wesl feature are gone.
• ScreenSpaceTransmission is opt-in. Camera3d no longer requires it. Add bevy::pbr::ScreenSpaceTransmission::default() to the camera or transmissive materials render without refraction.
• Tonemapping::None is a pure passthrough (no grading, no dither, no clamp). For "no tone curve, keep the rest" use Tonemapping::Linear.
• Hand-rolled AsBindGroup: unprepared_bind_group is now build_bind_group writing into a BindGroupBuilder. #[derive(AsBindGroup)] users are unaffected.
• OIT is per-material. Override Material::enable_oit(); the shader def is MATERIAL_OIT_ENABLED.
• bevy_shape split from bevy_math. Cuboid, Sphere, etc. still come through bevy::prelude::*; direct paths are bevy::shape::*.

0.18 → 0.19

• shadows_enabled → shadow_maps_enabled on PointLight, DirectionalLight, SpotLight. New contact_shadows_enabled field plus the ContactShadows camera component.
• Atmosphere is an entity, in bevy::light. Spawn Atmosphere::earth(medium) on its own entity; the camera keeps AtmosphereSettings. scene_units_to_m is gone (scale the entity's Transform). Atmosphere::earthlike → Atmosphere::earth.
• glTF materials: #Material0 now loads a GltfMaterial. Append /std for a Handle<StandardMaterial>.
• Skybox.image is Option<Handle<Image>> and Skybox lives in bevy::light.
• AlphaMode moved to bevy_material (prelude still exports it).
• Bloom luma is linear. Scenes look dimmer; raise Bloom::intensity or emissive strength.
• Render graph nodes are systems. ViewNode / add_render_graph_node are gone; write a system with ViewQuery in Core3d.

Still true

• Use Mesh3d(handle) and MeshMaterial3d(handle) — the renderer queries the wrappers.
• Plane3d::new takes Vec2 for half_size. Color::rgb is gone; use Color::srgb.
• Directional light position is ignored; only rotation matters.
• MaterialPlugin::<M> has no prepass_enabled / shadows_enabled fields; override Material::enable_prepass() / enable_shadows().

See also

• bevy-cameras — Camera3d, Hdr, Tonemapping, render targets.
• bevy-vfx — custom-material shader effects and GPU particles.
• bevy-migration-0-19-to-0-20 — WESL translation and ScreenSpaceTransmission.
• bevy-migration-0-18-to-0-19 — light field renames, Atmosphere entity, render systems.