geometry/polygon.rs
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//! Integer coordinate polygons.
use std::cmp::Ordering;
use serde::{Deserialize, Serialize};
use crate::bbox::Bbox;
use crate::contains::{Containment, Contains};
use crate::point::Point;
use crate::rect::Rect;
use crate::transform::{TransformMut, TransformRef, Transformation, TranslateMut, TranslateRef};
/// A polygon, with vertex coordinates given
#[derive(Debug, Default, Clone, Serialize, Deserialize, Hash, PartialEq, Eq, PartialOrd, Ord)]
pub struct Polygon {
/// Vector of points that make up the polygon.
points: Vec<Point>,
}
impl Polygon {
/// Creates a polygon with given vertices.
pub fn from_verts(vec: Vec<Point>) -> Self {
Self { points: vec }
}
/// Returns the bottom y-coordinate in the polygon.
///
/// # Example
///
/// ```
/// # use geometry::prelude::*;
/// let points = vec![
/// Point { x: 0, y: 0 },
/// Point { x: 1, y: 2 },
/// Point { x: -4, y: 5 },
/// ];
/// let polygon = Polygon::from_verts(points);
/// assert_eq!(polygon.bot(), 0);
/// ```
pub fn bot(&self) -> i64 {
self.points.iter().map(|point| point.y).min().unwrap()
}
/// Returns the top y-coordinate in the polygon.
///
/// # Example
///
/// ```
/// # use geometry::prelude::*;
/// let points = vec![
/// Point { x: 0, y: 0 },
/// Point { x: 1, y: 2 },
/// Point { x: -4, y: 5 },
/// ];
/// let polygon = Polygon::from_verts(points);
/// assert_eq!(polygon.top(), 5);
/// ```
pub fn top(&self) -> i64 {
self.points.iter().map(|point| point.y).max().unwrap()
}
/// Returns the leftmost x-coordinate in the polygon.
///
/// # Example
///
/// ```
/// # use geometry::prelude::*;
/// let points = vec![
/// Point { x: 0, y: 0 },
/// Point { x: 1, y: 2 },
/// Point { x: -4, y: 5 },
/// ];
/// let polygon = Polygon::from_verts(points);
/// assert_eq!(polygon.left(), -4);
/// ```
pub fn left(&self) -> i64 {
self.points.iter().map(|point| point.x).min().unwrap()
}
/// Returns the rightmost x-coordinate in the polygon.
///
/// # Example
///
/// ```
/// # use geometry::prelude::*;
/// let points = vec![
/// Point { x: 0, y: 0 },
/// Point { x: 1, y: 2 },
/// Point { x: -4, y: 5 },
/// ];
/// let polygon = Polygon::from_verts(points);
/// assert_eq!(polygon.right(), 1);
/// ```
pub fn right(&self) -> i64 {
self.points.iter().map(|point| point.x).max().unwrap()
}
/// Returns a the vector of points representing the polygon.
pub fn points(&self) -> &Vec<Point> {
&self.points
}
/// Returns the center point of the polygon.
///
/// Returns a point with x-coordinate equal to the average of all x-coordinates
/// and y-coordinate equal to the average of all y-coordinates.
/// Note that the current behavior is to round down.
///
/// # Example
///
/// ```
/// # use geometry::prelude::*;
/// let points = vec![
/// Point { x: 0, y: 0 },
/// Point { x: 1, y: 2 },
/// Point { x: -4, y: 5 },
/// ];
/// let polygon = Polygon::from_verts(points);
/// assert_eq!(polygon.center(), Point::new(-1, 2));
/// ```
pub fn center(&self) -> Point {
let x = self.points.iter().map(|point| point.x).sum::<i64>() / self.points.len() as i64;
let y = self.points.iter().map(|point| point.y).sum::<i64>() / self.points.len() as i64;
Point::new(x, y)
}
}
impl Bbox for Polygon {
fn bbox(&self) -> Option<Rect> {
let polygon = self;
Rect::from_sides_option(
polygon.left(),
polygon.bot(),
polygon.right(),
polygon.top(),
)
}
}
impl TranslateRef for Polygon {
fn translate_ref(&self, p: Point) -> Self {
Self {
points: self.points.translate_ref(p),
}
}
}
impl TranslateMut for Polygon {
fn translate_mut(&mut self, p: Point) {
self.points.translate_mut(p);
}
}
impl TransformRef for Polygon {
fn transform_ref(&self, trans: Transformation) -> Self {
Self {
points: self.points.transform_ref(trans),
}
}
}
impl TransformMut for Polygon {
fn transform_mut(&mut self, trans: Transformation) {
self.points.transform_mut(trans);
}
}
impl Contains<Point> for Polygon {
/// Determines if a point is contained within a polygon.
///
/// # Example
///
/// ```
/// # use geometry::prelude::*;
/// let points = vec![
/// Point { x: -4, y: 0 },
/// Point { x: 0, y: 0 },
/// Point { x: 1, y: 2 },
/// Point { x: 2, y: 2 },
/// Point { x: -4, y: 5 },
/// ];
/// let p1 = Point::new(0,0);
/// let p2 = Point::new(0,4);
/// let p3 = Point::new(-5,3);
/// let p4 = Point::new(-2,4);
/// let p5 = Point::new(-2,2);
/// let polygon = Polygon::from_verts(points);
/// assert_eq!(polygon.contains(&p1), Containment::Full);
/// assert_eq!(polygon.contains(&p2), Containment::None);
/// assert_eq!(polygon.contains(&p3), Containment::None);
/// assert_eq!(polygon.contains(&p4), Containment::Full);
/// assert_eq!(polygon.contains(&p5), Containment::Full);
/// ```
fn contains(&self, p: &Point) -> Containment {
use std::cmp::{max, min};
let mut contains = false;
for i in 0..self.points().len() {
let p0 = self.points[i];
let p1 = self.points[(i + 1) % self.points.len()];
// Ensure counter-clockwise ordering.
let (p0, p1) = if p0.y < p1.y { (p0, p1) } else { (p1, p0) };
let miny = min(p0.y, p1.y);
let maxy = max(p0.y, p1.y);
if p.y >= miny && p.y <= maxy {
let dy = p1.y - p0.y;
let dx = p1.x - p0.x;
let test = -(p.x - p0.x) * dy + (p.y - p0.y) * dx;
match test.cmp(&0) {
Ordering::Greater => {
// Note: this edge cannot be horizontal.
if p.y > miny {
contains = !contains;
}
}
Ordering::Equal => {
if p.x >= min(p0.x, p1.x) && p.x <= max(p0.x, p1.x) {
return Containment::Full;
}
}
_ => {}
}
}
}
if contains {
Containment::Full
} else {
Containment::None
}
}
}
#[cfg(test)]
mod tests {
use geometry::prelude::*;
#[test]
fn point_in_polygon() {
let points = vec![
Point { x: -4, y: 0 },
Point { x: 0, y: 0 },
Point { x: 1, y: 2 },
Point { x: 2, y: 2 },
Point { x: -4, y: 5 },
];
let p1 = Point::new(0, 0);
let p2 = Point::new(0, 4);
let p3 = Point::new(-5, 3);
let p4 = Point::new(-2, 4);
let p5 = Point::new(-2, 2);
let polygon = Polygon::from_verts(points);
assert_eq!(polygon.contains(&p1), Containment::Full);
assert_eq!(polygon.contains(&p2), Containment::None);
assert_eq!(polygon.contains(&p3), Containment::None);
assert_eq!(polygon.contains(&p4), Containment::Full);
assert_eq!(polygon.contains(&p5), Containment::Full);
let points = vec![
Point::new(-10, 0),
Point::new(-10, -10),
Point::new(10, -10),
Point::new(10, 0),
Point::new(5, 0),
Point::new(5, 5),
Point::new(-5, 5),
Point::new(-5, 0),
];
let polygon = Polygon::from_verts(points);
assert_eq!(polygon.contains(&Point::new(-10, 5)), Containment::None);
assert_eq!(polygon.contains(&Point::new(-10, 3)), Containment::None);
assert_eq!(polygon.contains(&Point::new(0, 5)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(5, 5)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(0, 2)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(-5, -5)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(-10, -10)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(-10, -12)), Containment::None);
assert_eq!(polygon.contains(&Point::new(12, -10)), Containment::None);
assert_eq!(polygon.contains(&Point::new(7, 3)), Containment::None);
assert_eq!(polygon.contains(&Point::new(5, 3)), Containment::Full);
let points = vec![
Point::new(0, 0),
Point::new(0, 5),
Point::new(10, 5),
Point::new(10, 0),
];
let polygon = Polygon::from_verts(points);
assert_eq!(polygon.contains(&Point::new(-1, 0)), Containment::None);
assert_eq!(polygon.contains(&Point::new(0, 0)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(3, 0)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(10, 0)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(12, 0)), Containment::None);
assert_eq!(polygon.contains(&Point::new(-1, 5)), Containment::None);
assert_eq!(polygon.contains(&Point::new(0, 5)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(3, 5)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(10, 5)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(12, 5)), Containment::None);
let points = vec![Point::new(0, 0), Point::new(10, 10), Point::new(20, 0)];
let polygon = Polygon::from_verts(points);
assert_eq!(polygon.contains(&Point::new(0, 10)), Containment::None);
assert_eq!(polygon.contains(&Point::new(10, 10)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(20, 10)), Containment::None);
assert_eq!(polygon.contains(&Point::new(3, 3)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(14, 6)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(2, 1)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(12, 7)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(-2, 0)), Containment::None);
assert_eq!(polygon.contains(&Point::new(0, 0)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(10, 0)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(20, 0)), Containment::Full);
assert_eq!(polygon.contains(&Point::new(21, 0)), Containment::None);
}
}