gl-aliased-vao/lib/vao-emulated.js

like vao, but only for simple vertex arrays

var bindAttribs = require("./do-bind.js")

function VAOEmulated(gl) {
  this.gl = gl
  this._elements = null
  this._attributes = null
  this._elementsType = gl.UNSIGNED_SHORT
}

VAOEmulated.prototype.bind = function(shader) {
  if (!shader)
    throw new Error('must associate shader with vertex array')
  bindAttribs(this.gl, this._elements, this._attributes, shader)
}

VAOEmulated.prototype.update = function(attributes, elements, elementsType) {
  this._elements = elements
  this._attributes = attributes
  this._elementsType = elementsType || this.gl.UNSIGNED_SHORT
}

VAOEmulated.prototype.dispose = function() { }
VAOEmulated.prototype.unbind = function() {
  bindAttribs(this.gl)
}

VAOEmulated.prototype.draw = function(mode, count, offset) {
  offset = offset || 0
  var gl = this.gl
  if(this._elements) {
    gl.drawElements(mode, count, this._elementsType, offset)
  } else {
    gl.drawArrays(mode, offset, count)
  }
}

function createVAOEmulated(gl) {
  return new VAOEmulated(gl)
}

module.exports = createVAOEmulated