experiment/src/scenes/scene1/ground.rs

use bevy::prelude::*;
use bevy_rapier3d::prelude::*;

pub fn spawn_ground(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    commands
        .spawn(Collider::cuboid(20.0, 0.1, 20.0))
        .insert(TransformBundle::from(Transform::from_xyz(0.0, -2.0, 0.0)))
        .insert(RigidBody::Fixed)
        .insert(PbrBundle {
            mesh: meshes.add(shape::Plane::from_size(40.0).into()),
            material: materials.add(StandardMaterial {
                base_color: Color::WHITE,
                perceptual_roughness: 1.0,
                ..default()
            }),
            ..default()
        });
}