ray-aabb

test if a ray intersects an aabb in 2d/3d space

Implemented via the techniques described in Fast Ray/Axis-Aligned Bounding Box Overlap Tests using Ray Slopes

install

npm install ray-aabb

use

``javascript
var createRay = require('ray-aabb');

/*
+------+
/ /|
(-1, 1, 0) ----> +------+ |
| | +
| |/
+------+
*/

var ray_origin = [-1, 1, 0];
var ray_direction = [1, 0, 0];
var ray = createRay(ray_origin, ray_direction);

var box = [
[0, 0, 0],
[2, 2, 2]
];

console.log(ray.intersects(box));
// outputs: true

// avoid allocating new memory by reusing rays
ray.update(ray_origin, [-1, 0, 0]);

console.log(ray.intersects(box));
// outputs: false

var normal = [0, 0, 0];
var d = ray.intersects(box, normal);
console.log(d);
// outputs: 1

console.log(normal);
// outputs: [ -1, 0, 0 ]
`

api surface

all vectors specified are arrays in the format: [x, y, z] with z being optional for 2d vectors

__createRay__(ray_origin, ray_direction)

_parameters_:

* ray_origin - a vector defining the ray origin
* ray_direction - a _normalized_ vector defining the ray direction
_returns_: a Ray instance

---

__Ray#update__(ray_origin, ray_direction)


Allows Ray instances to be reused by precomputing ray classification. The intention here is that you will be casting a ray against __many__ aabbs

_parameters_: same as __createRay__

_returns_: this (e.g. ray.update(ro, rd).intersects(box)

---

__Ray#intersects__(aabb[, normal])
where aabb specifies the corners of the bounding box:

`javascript
[[x1, y1, z1], [x2, y2, z2]]
`

and the optional normal argument is a 2d/3d vector (e.g., [0, 0]) that will be populated with the _non-normalized_ normal of the corner/edge/face that the ray intersected with.

_returns_

if normal is not passed

* true if intersection detected
* false if no intersection

if normal is passed:

* false if no intersection or a number denoting how far along the ray the collision occurred. You can use this number to compute the point of intersection. See the demos for example usage.

platforms

node and evergreen browsers using browserify

Demos

$3

!random-ray

npm run demo-2d

$3

!random-ray

npm run demo-raytracer`

license

MIT