text: /****************************************************************************
   Copyright (c) 2010-2012 cocos2d-x.org
   Copyright (c) 2008-2010 Ricardo Quesada
   Copyright (c) 2011      Zynga Inc.
  
   http://www.cocos2d-x.org
  
   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
   in the Software without restriction, including without limitation the rights
   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:
  
   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.
  
   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   THE SOFTWARE.
   ****************************************************************************/
  
  /**
   * cc.Configuration contains some openGL variables
   * @class
   * @extends cc.Class
   */
  cc.Configuration = cc.Class.extend(/** @lends cc.Configuration# */{
      _maxTextureSize:0,
      _maxModelviewStackDepth:0,
      _supportsPVRTC:false,
      _supportsNPOT:false,
      _supportsBGRA8888:false,
      _supportsDiscardFramebuffer:false,
      _supportsShareableVAO:false,
      _maxSamplesAllowed:0,
      _maxTextureUnits:0,
      _GlExtensions:"",
  
      /**
       * OpenGL Max texture size.
       * @return {Number}
       */
      getMaxTextureSize:function () {
          return this._maxTextureSize;
      },
  
      /**
       * OpenGL Max Modelview Stack Depth.
       * @return {Number}
       */
      getMaxModelviewStackDepth:function () {
          return this._maxModelviewStackDepth;
      },
  
      /**
       * returns the maximum texture units
       * @return {Number}
       */
      getMaxTextureUnits:function () {
          return this._maxTextureUnits;
      },
  
      /**
       * Whether or not the GPU supports NPOT (Non Power Of Two) textures.
       * OpenGL ES 2.0 already supports NPOT (iOS).
       * @return {Boolean}
       */
      supportsNPOT:function () {
          return this._supportsNPOT;
      },
  
      /**
       * Whether or not PVR Texture Compressed is supported
       * @return {Boolean}
       */
      supportsPVRTC:function () {
          return this._supportsPVRTC;
      },
  
      /**
       * Whether or not BGRA8888 textures are supported.
       * @return {Boolean}
       */
      supportsBGRA8888:function () {
          return this._supportsBGRA8888;
      },
  
      /**
       * Whether or not glDiscardFramebufferEXT is supported
       * @return {Boolean}
       */
      supportsDiscardFramebuffer:function () {
          return this._supportsDiscardFramebuffer;
      },
  
      /**
       * Whether or not shareable VAOs are supported.
       * @return {Boolean}
       */
      supportsShareableVAO:function () {
          return this._supportsShareableVAO;
      },
  
      /**
       * returns whether or not an OpenGL is supported
       * @param {String} searchName
       */
      checkForGLExtension:function (searchName) {
          return this._GlExtensions.indexOf(searchName) > -1;
      },
  
      init:function () {
          if(cc.renderContextType === cc.CANVAS)
              return true;
  
          var gl = cc.renderContext;
          cc.log("cocos2d: GL_VENDOR:     " + gl.getParameter(gl.VENDOR));
          cc.log("cocos2d: GL_RENDERER:   " + gl.getParameter(gl.RENDERER));
          cc.log("cocos2d: GL_VERSION:    " + gl.getParameter(gl.VERSION));
  
          this._GlExtensions = "";
          var extArr = gl.getSupportedExtensions();
          for (var i = 0; i < extArr.length; i++)
              this._GlExtensions += extArr[i] + " ";
          cc.log("cocos2d: GL_EXTENSIONS:  " + this._GlExtensions);
  
          this._maxTextureSize = gl.getParameter(gl.MAX_TEXTURE_SIZE);
          this._maxTextureUnits = gl.getParameter(gl.MAX_COMBINED_TEXTURE_IMAGE_UNITS);
  
          this._supportsPVRTC = this.checkForGLExtension("GL_IMG_texture_compression_pvrtc");
          this._supportsNPOT = true;
          this._supportsBGRA8888 = this.checkForGLExtension("GL_IMG_texture_format_BGRA888");
          this._supportsDiscardFramebuffer = this.checkForGLExtension("GL_EXT_discard_framebuffer");
  
          this._supportsShareableVAO = this.checkForGLExtension("vertex_array_object");
  
          cc.log("cocos2d: GL_MAX_TEXTURE_SIZE: " + this._maxTextureSize);
          cc.log("cocos2d: GL_MAX_TEXTURE_UNITS: " + this._maxTextureUnits);
          cc.log("cocos2d: GL supports PVRTC: " + (this._supportsPVRTC ? "YES" : "NO"));
          cc.log("cocos2d: GL supports BGRA8888 textures: " + (this._supportsBGRA8888 ? "YES" : "NO"));
          cc.log("cocos2d: GL supports NPOT textures: " + (this._supportsNPOT ? "YES" : "NO"));
          cc.log("cocos2d: GL supports discard_framebuffer: " + (this._supportsDiscardFramebuffer ? "YES" : "NO"));
          cc.log("cocos2d: GL supports shareable VAO: " + (this._supportsShareableVAO ? "YES" : "NO"));
  
          if (cc.ENABLE_GL_STATE_CACHE == 0)
              cc.log("cocos2d: **** WARNING **** CC_ENABLE_GL_STATE_CACHE is disabled. To improve performance, enable it by editing ccConfig.h");
  
          cc.CHECK_GL_ERROR_DEBUG();
          return true;
      }
  });
  
  
  cc.Configuration._sharedConfiguration = null;
  
  /**
   * returns a shared instance of CCConfiguration
   * @return {cc.Configuration}
   */
  cc.Configuration.getInstance = function () {
      if(!cc.Configuration._sharedConfiguration){
          cc.Configuration._sharedConfiguration = new cc.Configuration();
          cc.Configuration._sharedConfiguration.init();
      }
      return cc.Configuration._sharedConfiguration;
  };
  
  /**
   * purge the shared instance of CCConfiguration
   */
  cc.Configuration.purgeConfiguration = function () {
      cc.Configuration._sharedConfiguration = null;
  };