Method new

src/main.rs:480–513

(args: Args, w: usize, h: usize)

        let left = pos + dir_left;
        let rand_choice = rand::random::<f32>();
        if self.is_in_bounds(&down) && !self.is_empty(&down) {
            if rand_choice < 0.2 && self.is_in_bounds(&left) && self.is_empty(&left) {
                self.swap(&left, &down);
            } else if rand_choice >= 0.8 && self.is_in_bounds(&right) && self.is_empty(&right) {
                self.swap(&right, &down);
            } else if self.is_empty(&down) {
                self.swap(&pos, &down);
            }
        }
    }

    fn step(&mut self, args: &Args, dir: &Vec2) {
        self.flip = (self.flip + 1) % self.flip_rate;
        if self.flip != 0 {
            return;
        }
        let yrange: Box<dyn Iterator<Item = usize>> = match dir.y {
            -1 => Box::new((1..self.height).rev()), // down (process from bottom up)
            _ => Box::new(0..self.height - 1),      // up
        };
        let xrange: Box<dyn Iterator<Item = usize>> = match dir.x {
            -1 => Box::new((1..self.width).rev()),
            _ => Box::new(0..self.width - 1),
        };
        self.spawn(args, dir);
        if dir.x == 0 {
            for y in yrange {
                for x in 0..self.width {
                    let pos = Vec2 {
                        x: x as isize,
                        y: y as isize,
                    };
                    self.step_fall(pos, *dir);
                }
            }
        } else {
            for x in xrange {