drawing test

test.rs

use bevy::prelude::shape::{Cube, UVSphere};
use bevy::prelude::*;
use rand::Rng;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_startup_system(spawn_test_world)
        .add_startup_system(spawn_character)
        .run();
}

fn spawn_test_world(
    mut commands: Commands,
    mut materials: ResMut<Assets<StandardMaterial>>,
    mut meshes: ResMut<Assets<Mesh>>,
) {
    let cube = meshes.add(Mesh::from(Cube { size: 1.0 }));
    let sphere = meshes.add(Mesh::from(UVSphere::default()));

    #[derive(Debug, Bundle, Default)]
    struct LightBundle {
        directional_light: DirectionalLight,
        transform: Transform,
        global_transform: GlobalTransform,
    }

    //spawn a light
    commands.spawn_bundle(LightBundle {
        directional_light: DirectionalLight::default(),
        transform: Transform::from_xyz(0.0, 0.0, 0.0),
        global_transform: GlobalTransform::identity(),
    });

    // a floor
    let grey = materials.add(Color::hex("2B2D2E").unwrap().into());
    let orange = materials.add(Color::rgb(251.0 / 255.0, 99.0 / 255.0, 21.0 / 255.0).into());
    let blue = materials.add(Color::rgb(182.0 / 255.0, 226.0 / 255.0, 245.0 / 255.0).into());
    commands.spawn_bundle(PbrBundle {
        material: grey,
        mesh: cube.clone(),
        transform: Transform::from_matrix(Mat4::from_scale_rotation_translation(
            Vec3::new(20.0, 1.0, 20.0),
            Quat::IDENTITY,
            -Vec3::Y,
        )),
        ..Default::default()
    });

    // some shapes for reference
    let scale = 0.5;
    let mut rng = rand::thread_rng();
    for _ in 0..20 {
        let x = rng.gen_range(-10.0..10.0);
        let z = rng.gen_range(-10.0..10.0);
        commands.spawn_bundle(PbrBundle {
            material: orange.clone(),
            mesh: cube.clone(),
            transform: Transform::from_matrix(Mat4::from_scale_rotation_translation(
                Vec3::splat(scale),
                Quat::IDENTITY,
                Vec3::new(x, 0.5 * (scale - 1.0), z),
            )),
            ..Default::default()
        });

        let x = rng.gen_range(-10.0..10.0);
        let z = rng.gen_range(-10.0..10.0);
        commands.spawn_bundle(PbrBundle {
            material: blue.clone(),
            mesh: sphere.clone(),
            transform: Transform::from_matrix(Mat4::from_scale_rotation_translation(
                Vec3::splat(scale),
                Quat::IDENTITY,
                Vec3::new(x, 0.5 * (scale - 1.0), z),
            )),
            ..Default::default()
        });
    }
}

pub fn spawn_character(mut commands: Commands) {
    commands
        .spawn_bundle(PerspectiveCameraBundle {
            transform: Transform::from_matrix(Mat4::face_toward(
                Vec3::new(0.0, 4.0, 8.0),
                Vec3::ZERO,
                Vec3::Y,
            )),
            ..Default::default()
        })
        .id();
}