fn make_mesh(world: &mut World) -> Handle<Mesh>
{
    use amethyst::renderer::rendy::mesh::{MeshBuilder, Position, TexCoord};
    use amethyst::renderer::types::MeshData;

    let loader = world.read_resource::<Loader>();

    let verts = vec![
        Position([-1.0, -1.0, 0.0]),
        Position([ 1.0, -1.0, 0.0]),
        Position([ 1.0,  1.0, 0.0]),
        Position([-1.0,  1.0, 0.0]),
    ];

    let tex = vec![
        TexCoord([0.0, 0.0]),
        TexCoord([1.0, 0.0]),
        TexCoord([1.0, 1.0]),
        TexCoord([0.0, 1.0]),
    ];

    let mesh_store = &world.read_resource();

    let m = MeshBuilder::new()
        .with_vertices(verts)
        .with_vertices(tex);

    loader.load_from_data(MeshData::from(m), (), mesh_store)
}

fn make_texture(world: &mut World) -> Handle<Texture>
{
    use amethyst::renderer::types::TextureData;

    let loader = world.read_resource::<Loader>();

    let tex_store = &world.read_resource();

    let t = amethyst::renderer::loaders::load_from_linear_rgba(
        amethyst::renderer::palette::Alpha
        {
            color: amethyst::renderer::palette::rgb::LinSrgb::new(1.0, 0.0, 0.0),
            alpha: 1.0
        }
    );

    loader.load_from_data(t.into(), (), tex_store)
}

fn make_material(world: &mut World, tex: Handle<Texture>) -> Handle<Material>
{
    use amethyst::renderer::MaterialDefaults;

    let loader = world.read_resource::<Loader>();

    let mat_store = &world.read_resource();

    let mat = Material
    {
        albedo: tex,
        ..world.read_resource::<MaterialDefaults>().0.clone()
    };

    loader.load_from_data(mat, (), mat_store)
}

fn init_square(world: &mut World, mesh: Handle<Mesh>, mat: Handle<Material>)
{
    let mut transform = Transform::default();
    transform.set_translation_xyz(WIDTH / 2.0, HEIGHT / 2.0, 0.0);

    world.create_entity()
        .with(mesh)
        .with(mat)
        .with(transform)
        .build();
}