Bevy shaders and materials

When to use

Load this when a surface needs a custom material or a full-screen effect. StandardMaterial field lists stay on bevy-3d-materials. Shader source is WGSL loaded as an asset.

ECS shape

• Shader asset: AssetServer loads a Shader from a path. ShaderRef::Handle or a path string points a material at that asset.
• Material: implement Material, derive AsBindGroup, and register MaterialPlugin::<T>. The engine extracts materials. Do not schedule a shader compiler.
• Full-screen: Bloom is a camera component from bevy::post_process. It requires an HDR camera, which the component requests itself.

Examples

[dependencies]
bevy = "0.20"

A material stores a color uniform and names its fragment shader. Register the plugin before any system spawns that material.

use bevy::pbr::{Material, MaterialPlugin};
use bevy::render::render_resource::AsBindGroup;
use bevy::shader::ShaderRef;

#[derive(Asset, TypePath, AsBindGroup, Clone)]
struct PulseMaterial {
    #[uniform(0)]
    color: LinearRgba,
}

impl Material for PulseMaterial {
    fn fragment_shader() -> ShaderRef {
        "shaders/pulse.wgsl".into()
    }
}

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(MaterialPlugin::<PulseMaterial>::default())
        .run();
}

Spawn uses the same mesh and material components as a PBR surface. The asset store owns the material.

use bevy::pbr::Material;
use bevy::render::render_resource::AsBindGroup;
use bevy::shader::ShaderRef;

#[derive(Asset, TypePath, AsBindGroup, Clone)]
struct PulseMaterial {
    #[uniform(0)]
    color: LinearRgba,
}

impl Material for PulseMaterial {
    fn fragment_shader() -> ShaderRef {
        "shaders/pulse.wgsl".into()
    }
}

fn spawn_pulse(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<PulseMaterial>>,
) {
    let mesh = meshes.add(Cuboid::new(1.0, 1.0, 1.0));
    let material = materials.add(PulseMaterial {
        color: LinearRgba::rgb(0.2, 0.7, 0.9),
    });
    commands.spawn((
        Mesh3d(mesh),
        MeshMaterial3d(material),
        Transform::default(),
    ));
}

Load the shader yourself when the handle must be explicit. ShaderRef accepts that handle.

use bevy::shader::{Shader, ShaderRef};

#[derive(Resource)]
struct PulseShader(Handle<Shader>);

fn load_pulse(asset_server: Res<AssetServer>, mut commands: Commands) {
    let handle: Handle<Shader> = asset_server.load("shaders/pulse.wgsl");
    commands.insert_resource(PulseShader(handle));
}

fn shader_ref(shader: Res<PulseShader>) -> ShaderRef {
    shader.0.clone().into()
}

Bloom is the full-screen pass. Intensity is the scene-wide scatter amount.

use bevy::post_process::bloom::Bloom;

fn spawn_bloom_camera(mut commands: Commands) {
    commands.spawn((
        Camera3d::default(),
        Bloom {
            intensity: 0.2,
            ..default()
        },
    ));
}

Same job, Bevy types

Design	Bevy idiom
ShaderMaterial	Material plus a WGSL path in fragment_shader
Spatial shader	Vertex and fragment ShaderRef on that material
Full-screen pass	Bloom (or another bevy::post_process component) on the camera

Scope

WGSL entry points live in the shader file the ShaderRef names. Bindings are the AsBindGroup fields on the material struct. Pipeline specialization stays inside the material plugin.

Expert Knowledge Delta

Target: Bevy 0.20+.

Core ECS types: Component, Resource, Query, Commands, Startup, Update, Fixed / FixedMain (bevy::time), .chain(), Plugin, DefaultPlugins, MinimalPlugins. Messages and observers are an ownership slot. See bevy-events-messaging for their APIs. Systems run in parallel unless .chain() orders the ones that conflict.

Who owns state

Piece	Owner	Who may mutate	Schedule
Data on one entity	Component	One system via Query	Update or FixedMain
One value for the whole app	Resource	One system	Startup to insert, then the schedule that reads it
Spawn	Commands	The spawning system	Startup for the initial world; later schedules for runtime spawn
Order that must not race	.chain()	The chained systems only	Same schedule
Plugin boundary	Plugin	build registers systems and resources	Before the app runs

Borrow rule: two systems that both mutably query the same component must be ordered (.chain()) or split so only one writes. Unrelated systems stay parallel. That is the ECS page rule, not a guess at a system-set API.

Decision

If you need	Do this	Do not
Per-entity data	Component + Query	A scene-tree script hung on the entity
App-wide config or clock	Resource	Copy the value onto every entity
Stable simulation step	FixedMain and the Fixed clock	Tie simulation to raw frame Update
Startup spawn	Commands in Startup	Spawn from a render system
Cross-system notice that is not shared state	Message or observer slot in bevy-events-messaging	A new event type invented in this file
An API outside the documented set	Check the official docs first	A made-up crate or API

Load references/ecs-ownership.md for the ownership table.

NEVER

• Do not pin /0.20.0/ in docs URLs. WHY: links stay on latest; the 0.20 target is stated once in prose.

• Do not mutably query the same component from two unordered systems. WHY: the schedule runs systems in parallel unless .chain() orders them.

• Do not invent a physics, navigation, networking, or XR crate here. WHY: this skill only names documented Bevy crates and modules.

• No Godot shader language or hint syntax. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.

• No Godot types in Bevy code. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.

• No invented APIs or unnamed third-party crates as the chosen solver. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.

Reference

Official pages stay on unversioned bevy.org URLs. The library pin on bevy-master stays 0.20.0. Custom surfaces use Material, AsBindGroup, and MaterialPlugin. StandardMaterial field lists stay on bevy-3d-materials.

Official Documentation

• Assets - Official asset catalog. No third-party crate was selected.
• Examples - Example tree on the latest branch.
• ECS - Component, systems, Query, Startup, Update, and .chain().
• Plugins - Plugin, DefaultPlugins, MinimalPlugins, and add_plugins.

Related Skills

Prerequisites

• bevy-master - Hub and schedules.
• bevy-ecs-composition - Components and systems.
• bevy-3d-materials - StandardMaterial surface fields.
• bevy-asset-scenes - Asset handles.

Complements

• bevy-3d-lighting - Lights are not shaders.
• godot-shaders-basics - Equivalent Godot skill.

Downstream / consumers

• None yet.

Master

• bevy-master - Bevy router.