test whether a ray intersects with a sphere
npm install ray-sphere-intersection
Test whether a ray intersects with a sphere.
``js
var intersect = require('ray-sphere-intersection')
var origin = [0, 0, 4],
direction = [0, 0, -1],
center = [0, 0, 0],
radius = 1
var hit = intersect([], origin, direction, center, radius)
if (hit) {
console.log(hit) // [0, 0, 1]
}
`
Adapted from LibGDX. PRs for optimizations/etc welcome.

#### out = intersect(out, origin, direction, center, radius)
Determines if the 3D ray (origin, direction) intersects with the 3D sphere (center, radius).
If no intersection occurs, returns null. Otherwise, the intersection point is stored in out` and then returned.
MIT, see LICENSE.md for details.