Crate sepax2d

Expand description

sepax2d

A safe Rust crate for finding and resolving collisions of convex shapes using the Separating Axis Theorem (SAT) in two dimensions.

Usage

Add the following to the [dependencies] section of your Cargo.toml:

sepax2d = "0.3"

Import the types of shapes you’d like to use and create some new shapes:

use sepax2d::prelude::*;

let rectangle = AABB::new(top_left, width, height);
let circle = Circle::new(center, radius);
let capsule = Capsule::new(center, arm, radius);
let parallelogram = Parallelogram::new(position, u_vector, v_vector);

//The vertices of a polygon are position vectors
//relative to the shape's position, i.e. if position
//is (1, 2), then the absolute location of the
//first vertex is (1, 0).
let triangle = Polygon::from_vertices
(

    position,
    vec![(0.0, -2.0), (-1.0, 2.0), (1.0, 2.0)]

);

Use the sat_overlap(&left, &right) method to get a bool indicating whether or not the two given shapes overlap. Any struct implementing the Shape trait can be used.

assert!(sat_overlap(&circle, &capsule));
assert!(!sat_overlap(&triangle, &rectangle));

Use the sat_collision(&left, &right) method to get a (f32, f32) which represents the shift needed to add to right’s position in order to resolve the overlap of the two shapes.

let resolution = sat_collision(&circle, &triangle);

let position = triangle.position();
triangle.set_position((position.0 + resolution.0, position.1 + resolution.1));

assert!(!sat_overlap(&circle, &triangle));

Use the contains_point(&shape, point) method to get a bool indicating whether or not the specified point is inside the given shape.


let rect = AABB::new((0.0, 0.0), 5.0, 2.0);

assert!(contains_point(&rect, (1.0, 1.0)));
assert!(!contains_point(&rect, (10.0, -1.0)));

Polygon, Circle, Capsule, and Parallelogram shapes implement the Rotate trait, which allows you to rotate them around their position.


let mut triangle = Polygon::from_vertices
(

   position,
   vec![(-1.0, 0.0), (0.0, 2.0), (1.0, 0.0)]

);

triangle.rotate(std::f32::consts::FRAC_PI_2)
//New vertices: [(0.0, -1.0), (-2.0, 0.0), (0.0, 1.0)]

You can use the intersects_line, intersects_ray, and intersects_segment methods to check whether a shape intersects with the corresponding type of line.


let triangle = Polygon::from_vertices((0.0, vec![(0.0, 0.0), (1.0, 1.0), (-1.0, 1.0)]));

assert!(intersects_segment(&triangle, (2.0, 0.5), (-2.0, 0.5)));

Features

Enable the serde feature for (De)Serialization of supported shapes!

Modules

Macros

rotate

Traits

Rotate

A trait indicating that a shape can be rotated around its position. Applicable to all shapes other than AABB.

Shape

A trait describing the behavior needed to implement SAT overlap and collision for a given shape.

Functions

contains_point

Returns true if the given shape contains the specified point, and false if it does not. Does not work for degenerate polygons.

sat_collision

Returns the vector that needs to be added to the second shape’s position to resolve a collision with the first shape. Does not work for degenerate shapes.

sat_overlap

Returns true if the given shapes overlap, and false if they do not. Does not work for degenerate shapes.