RosettaCodeData/Task/Pythagoras-tree/Rust/pythagoras-tree.rust

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use svg::node::element::{Group, Polygon};
fn main() {
let mut base: Vec<[(f64, f64); 2]> = vec![[(-200., 0.), (200., 0.)]];
let doc = (0..12_u8).fold(svg::Document::new().set("stroke", "white"), |doc_a, lvl| {
let rg = |step| lvl.wrapping_mul(step).wrapping_add(80 - step * 2);
let g = Group::new().set("fill", format!("#{:02X}{:02X}18", rg(20), rg(30))); // level color
doc_a.add(base.split_off(0).into_iter().fold(g, |ga, [a, b]| {
let v = (b.0 - a.0, b.1 - a.1);
let [c, d, w] = [a, b, v].map(|p| (p.0 + v.1, p.1 - v.0));
let e = (c.0 + w.0 / 2., c.1 + w.1 / 2.);
base.extend([[c, e], [e, d]]);
ga.add(Polygon::new().set("points", vec![a, c, e, d, c, d, b]))
}))
});
let (x, y) = (base.iter()).fold((0., 0.), |(xa, ya), [p, _]| (p.0.min(xa), p.1.min(ya)));
svg::save("Pythagor_tree.svg", &doc.set("viewBox", (x, y, -x - x, -y))).unwrap();
}