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###
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  Various useful methods
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  @class bkcore.Utils
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  @author Thibaut 'BKcore' Despoulain <http://bkcore.com>
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###
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class Utils
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  ###
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    Creates a bkcore.threejs.Shaders["normalV"|"normal"] material
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    with given parameters
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  ###
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  @createNormalMaterial = (opts)->
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    opts ?= {}
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    opts.ambient ?= 0x444444
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    opts.normalScale ?= 1.0
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    opts.reflectivity ?= 0.9
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    opts.shininess ?= 42
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    opts.metal ?= false
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    shadername = if opts.perPixel then "normalV" else "normal"
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    shader = bkcore.threejs.Shaders[shadername]
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    uniforms = THREE.UniformsUtils.clone(shader.uniforms)
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    uniforms["enableDiffuse"].value = true
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    uniforms["enableSpecular"].value = true
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    uniforms["enableReflection"].value = !!opts.cube
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    uniforms["tNormal"].texture = opts.normal
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    uniforms["tDiffuse"].texture = opts.diffuse
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    uniforms["tSpecular"].texture = opts.specular
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    uniforms["uAmbientColor"].value.setHex(opts.ambient)
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    uniforms["uAmbientColor"].value.convertGammaToLinear()
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    uniforms["uNormalScale"].value = opts.normalScale
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    if opts.cube?
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      uniforms["tCube"].texture = opts.cube
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      uniforms["uReflectivity"].value = opts.reflectivity
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    parameters = {
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      fragmentShader: shader.fragmentShader
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      vertexShader: shader.vertexShader
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      uniforms: uniforms
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      lights: true
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      fog: false
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    }
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    material = new THREE.ShaderMaterial(parameters)
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    material.perPixel = true
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    material.metal = opts.metal
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    return material
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  ###
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    Projects an object origin vector to screen using given camera
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    @param  THREE.Object3D object The object which origin you want to project
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    @param  THREE.Camera camera The camera of the projection
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    @return THEE.Vector3 Projected verctor
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  ###
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  @projectOnScreen: (object, camera)->
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    mat = new THREE.Matrix4()
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    mat.multiply(camera.matrixWorldInverse, object.matrixWorld)
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    mat.multiply(camera.projectionMatrix , mat)
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    c = mat.n44
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    lPos = new THREE.Vector3(mat.n14/c, mat.n24/c, mat.n34/c)
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    return lPos.multiplyScalar(0.5).addScalar(0.5)
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  ###
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    Get an url parameter
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    @param  String name Parameter slug
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    @return Mixed
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  ###
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  @URLParameters: null
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  @getURLParameter: (name)->
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    if !@URLParameters?
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      @URLParameters = {}
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      window.location.href.replace(/[?&]+([^=&]+)=([^&]*)/gi, (m, key, val)=>
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        @URLParameters[key] = val
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      )
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    return @URLParameters[name]
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  ###
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    Get top offset of an element
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    @param obj HTMLElement
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  ###
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  @getOffsetTop: (obj)->
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    curtop = obj.offsetTop
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    if obj.offsetParent
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      while obj = obj.offsetParent
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        curtop += obj.offsetTop
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    return curtop
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  ###
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    Scrolls page to given element id
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    @param  string id The ID of the element
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  ###
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  @scrollTo: (id)->
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    window.scroll(0, @getOffsetTop(document.getElementById(id)))
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  ###
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    Add or remove a class from an element
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    @param  string id       [description]
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    @param  string cssclass [description]
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    @param  bool active   [description]
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  ###
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  @updateClass: (id, cssclass, active)->
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    e = document.getElementById(id)
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    return unless e?
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    if active
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      e.classList.add(cssclass)
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    else
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      e.classList.remove(cssclass)
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  ###
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    Performs an XMLHttpRequest
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    @param  string   url      [description]
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    @param  bool   postData true = POST, false = GET
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    @param  {Function} callback [description]
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    @param  {Object}   data     [description]
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  ###
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  @request: (url, postData, callback, data)->
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    XMLHttpFactories = [
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      ()-> return new XMLHttpRequest()
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      ()-> return new ActiveXObject("Msxml2.XMLHTTP")
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      ()-> return new ActiveXObject("Msxml3.XMLHTTP")
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      ()-> return new ActiveXObject("Microsoft.XMLHTTP")
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    ]
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    createXMLHTTPObject = () ->
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      xmlhttp = false
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      for i in [0..XMLHttpFactories.length]
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        try
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          xmlhttp = XMLHttpFactories[i]()
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        catch e
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          continue
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        break
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      return xmlhttp
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    req = createXMLHTTPObject()
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    return unless req?
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    method = if postData? then "POST" else "GET"
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    qdata = "o=bk"
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    if data?
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      for i, val of data
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        qdata += "&"+i+"="+val
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        url += "?"+qdata if postData?
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    req.open(method,url,true)
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    if postData?
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      req.setRequestHeader('Content-type','application/x-www-form-urlencoded')
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    req.onreadystatechange = () ->
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      return unless req.readyState is 4
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      return unless req.status is 200 or req.status is 304
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      callback?(req)
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    req.send(qdata)
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    return req
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  ###
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    Checks whether the device supports Touch input
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  ###
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  @isTouchDevice: ()->
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    return ('ontouchstart' of window) or
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        (navigator.MaxTouchPoints > 0) or
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        (navigator.msMaxTouchPoints > 0)
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###
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  Exports
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  @package bkcore
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###
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exports = exports ? @
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exports.bkcore ||= {}
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exports.bkcore.Utils = Utils
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