Macro render 

macro_rules! render {
    ($timeline:expr, $scene:expr $(,)?) => { ... };
}

Renders the whole timeline animation into the outputs/<scene> directory next to the .rs file where the macro is called; returns a std::io::Result carrying only success/failure. The number of saved frames is not returned — if you need it, call Timeline::render directly.

A convenient wrapper over Timeline::render and scene_dir!: the directory is chosen automatically, so a separate path macro call is not needed.

let tl = Timeline::new(480, 240, Color::BLACK, 30.0);
render!(tl, "demo").unwrap(); // → outputs/demo next to the .rs