Function intersection_exists 

pub fn intersection_exists(
    x1: f64,
    y1: f64,
    x2: f64,
    y2: f64,
    x3: f64,
    y3: f64,
    x4: f64,
    y4: f64,
) -> bool

Quick check whether two line segments (x1,y1)→(x2,y2) and (x3,y3)→(x4,y4) intersect (boundary excluded).