node-red-contrib-leap-motion/leapjs/lib/ui/region.js

Node-Red nodes for leap motion

var EventEmitter = require('events').EventEmitter
  , _ = require('underscore')

var Region = module.exports = function(start, end) {
  this.start = new Vector(start)
  this.end = new Vector(end)
  this.enteredFrame = null
}

Region.prototype.hasPointables = function(frame) {
  for (var i = 0; i != frame.pointables.length; i++) {
    var position = frame.pointables[i].tipPosition
    if (position.x >= this.start.x && position.x <= this.end.x && position.y >= this.start.y && position.y <= this.end.y && position.z >= this.start.z && position.z <= this.end.z) {
      return true
    }
  }
  return false
}

Region.prototype.listener = function(opts) {
  var region = this
  if (opts && opts.nearThreshold) this.setupNearRegion(opts.nearThreshold)
  return function(frame) {
    return region.updatePosition(frame)
  }
}

Region.prototype.clipper = function() {
  var region = this
  return function(frame) {
    region.updatePosition(frame)
    return region.enteredFrame ? frame : null
  }
}

Region.prototype.setupNearRegion = function(distance) {
  var nearRegion = this.nearRegion = new Region(
    [this.start.x - distance, this.start.y - distance, this.start.z - distance],
    [this.end.x + distance, this.end.y + distance, this.end.z + distance]
  )
  var region = this
  nearRegion.on("enter", function(frame) {
    region.emit("near", frame)
  })
  nearRegion.on("exit", function(frame) {
    region.emit("far", frame)
  })
  region.on('exit', function(frame) {
    region.emit("near", frame)
  })
}

Region.prototype.updatePosition = function(frame) {
  if (this.nearRegion) this.nearRegion.updatePosition(frame)
  if (this.hasPointables(frame) && this.enteredFrame == null) {
    this.enteredFrame = frame
    this.emit("enter", this.enteredFrame)
  } else if (!this.hasPointables(frame) && this.enteredFrame != null) {
    this.enteredFrame = null
    this.emit("exit", this.enteredFrame)
  }
  return frame
}

Region.prototype.normalize = function(position) {
  return new Vector([
    (position.x - this.start.x) / (this.end.x - this.start.x),
    (position.y - this.start.y) / (this.end.y - this.start.y),
    (position.z - this.start.z) / (this.end.z - this.start.z)
  ])
}

Region.prototype.mapToXY = function(position, width, height) {
  var normalized = this.normalize(position)
  var x = normalized.x, y = normalized.y
  if (x > 1) x = 1
  else if (x < -1) x = -1
  if (y > 1) y = 1
  else if (y < -1) y = -1
  return [
    (x + 1) / 2 * width,
    (1 - y) / 2 * height,
    normalized.z
  ]
}

_.extend(Region.prototype, EventEmitter.prototype)