src/viewer/stats.js

/**
 * @file Stats
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 * @private
 */

import Signal from '../../lib/signals.es6.js'

function Stats () {
  this.signals = {
    updated: new Signal()
  }

  this.begin()

  this.maxDuration = -Infinity
  this.minDuration = Infinity
  this.avgDuration = 14
  this.lastDuration = Infinity

  this.prevFpsTime = 0
  this.lastFps = Infinity
  this.lastFrames = 1
  this.frames = 0
  this.count = 0
}

Stats.prototype = {

  update: function () {
    this.startTime = this.end()
    this.currentTime = this.startTime
    this.signals.updated.dispatch()
  },

  begin: function () {
    this.startTime = window.performance.now()
    this.lastFrames = this.frames
  },

  end: function () {
    var time = window.performance.now()

    this.count += 1
    this.frames += 1

    this.lastDuration = time - this.startTime
    this.minDuration = Math.min(this.minDuration, this.lastDuration)
    this.maxDuration = Math.max(this.maxDuration, this.lastDuration)
    this.avgDuration -= this.avgDuration / 30
    this.avgDuration += this.lastDuration / 30

    if (time > this.prevFpsTime + 1000) {
      this.lastFps = this.frames
      this.prevFpsTime = time
      this.frames = 0
    }

    return time
  }

}

export default Stats