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Sutherland-Hodgman clipping algorithm in rust
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// Sutherland-Hodgman clipping algorithm, translated naively from : | |
// http://rosettacode.org/wiki/Sutherland-Hodgman_polygon_clipping#Ruby | |
// and posted back on : | |
// http://rosettacode.org/wiki/Sutherland-Hodgman_polygon_clipping#Rust | |
#[derive(Debug,Clone)] | |
struct Point { | |
x: f64, | |
y: f64 | |
} | |
#[derive(Debug,Clone)] | |
struct Polygon(Vec<Point>); | |
fn is_inside(p: &Point, cp1: &Point, cp2: &Point) -> bool { | |
(cp2.x - cp1.x) * (p.y - cp1.y) > (cp2.y - cp1.y) * (p.x - cp1.x) | |
} | |
fn compute_intersection(cp1: &Point, cp2: &Point, s: &Point, e: &Point) -> Point { | |
let dc = Point {x: cp1.x - cp2.x, y: cp1.y - cp2.y}; | |
let dp = Point {x: s.x - e.x, y: s.y - e.y}; | |
let n1 = cp1.x * cp2.y - cp1.y * cp2.x; | |
let n2 = s.x * e.y - s.y * e.x; | |
let n3 = 1.0 / (dc.x * dp.y - dc.y * dp.x); | |
Point { | |
x: (n1 * dp.x - n2 * dc.x) * n3, | |
y: (n1 * dp.y - n2 * dc.y) * n3 | |
} | |
} | |
fn sutherland_hodgman_clip(subject_polygon: &Polygon, clip_polygon: &Polygon) -> Polygon { | |
let mut result_ring = subject_polygon.0.clone(); | |
let mut cp1 = clip_polygon.0.last().unwrap(); | |
for cp2 in clip_polygon.0.iter() { | |
let input = result_ring; | |
let mut s = input.last().unwrap(); | |
result_ring = vec![]; | |
for e in input.iter() { | |
if is_inside(&e, &cp1, &cp2) { | |
if !is_inside(&s, &cp1, &cp2){ | |
result_ring.push(compute_intersection(&cp1, &cp2, &s, &e)); | |
} | |
result_ring.push(e.clone()); | |
} else if is_inside(&s, &cp1, &cp2){ | |
result_ring.push(compute_intersection(&cp1, &cp2, &s, &e)); | |
} | |
s = e; | |
} | |
cp1 = cp2; | |
} | |
Polygon(result_ring) | |
} | |
fn main(){ | |
let _p = |x: f64, y: f64| Point {x: x, y: y}; | |
let subject_polygon = Polygon( | |
vec![_p(50.0, 150.0), _p(200.0, 50.0), _p(350.0, 150.0), _p(350.0, 300.0), | |
_p(250.0, 300.0), _p(200.0, 250.0), _p(150.0, 350.0), _p(100.0, 250.0), _p(100.0, 200.0)]); | |
let clip_polygon = Polygon( | |
vec![_p(100.0, 100.0), _p(300.0, 100.0), _p(300.0, 300.0), _p(100.0, 300.0)]); | |
let result = Sutherland_Hodgman_clip(&subject_polygon, &clip_polygon); | |
println!("{:?}", result); | |
} |
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