ray-plane-intersection/index.js

whether a picking ray intersects with a plane

var dot = require('gl-vec3/dot')
var add = require('gl-vec3/add')
var scale = require('gl-vec3/scale')
var copy = require('gl-vec3/copy')

module.exports = intersectRayPlane

var v0 = [0, 0, 0]

function intersectRayPlane(out, origin, direction, normal, dist) {
  var denom = dot(direction, normal)
  if (denom !== 0) {
    var t = -(dot(origin, normal) + dist) / denom
    if (t < 0) {
      return null
    }
    scale(v0, direction, t)
    return add(out, origin, v0)
  } else if (dot(normal, origin) + dist === 0) {
    return copy(out, origin)
  } else {
    return null
  }
}