Simple quad material

main.rs

//! A shader and a material that uses it.

use bevy::{
    prelude::*,
    reflect::{TypePath, TypeUuid},
    render::render_resource::{AsBindGroup, ShaderRef},
};
use bevy_internal::window::WindowResized;

fn main() {
    App::new()
        .add_plugins((DefaultPlugins, MaterialPlugin::<CustomMaterial>::default()))
        .add_systems(Startup, setup)
        .run();
}

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<CustomMaterial>>,
    asset_server: Res<AssetServer>,
) {
    commands.spawn(MaterialMeshBundle {
        mesh: meshes.add(Mesh::from(shape::Quad {
            size: Vec2::new(16.0, 9.0) * 0.1,
            flip: false,
        })),
        transform: Transform::from_xyz(0.0, 0.5, 0.0),
        material: materials.add(CustomMaterial {}),
        ..default()
    });

    commands.spawn(Camera3dBundle {
        transform: Transform::from_xyz(0.0, 0.5, 1.0),
        ..default()
    });
}

#[derive(AsBindGroup, TypeUuid, TypePath, Debug, Clone)]
#[uuid = "f690fdae-d598-45ab-8225-97e2a3f056e0"]
pub struct CustomMaterial {}
impl Material for CustomMaterial {
    fn fragment_shader() -> ShaderRef {
        "simple_material.wgsl".into()
    }
}

simple_material.wgsl

#import bevy_pbr::mesh_vertex_output MeshVertexOutput

@fragment
fn fragment(
    mesh: MeshVertexOutput,
) -> @location(0) vec4<f32> {
    return vec4(mesh.uv.x, mesh.uv.y, 0.0, 1.0);
}