API Docs for: 0.5.5
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File: kick/core/WebGLDebugUtils.js

define(["./Constants"], function (Constants) {
    "use strict";

    /* /// Removed from documentation ///
     * This class contains the webgl-debug.js. Note is is only defined in debug builds.
     * @class WebGLDebugUtils
     * @namespace kick.core
     * @static
     */
    if (!Constants._DEBUG) {
        return {};
    } else {
        // based on the webgl-debug.js
        // https://www.khronos.org/registry/webgl/sdk/debug/webgl-debug.js
        // Various functions for helping debug WebGL apps.
        return function () {

            /*
             * Wrapped logging function.
             * @param {string} msg Message to log.
             */
            var log = function(msg) {
                if (window.console && window.console.log) {
                    window.console.log(msg);
                }
            };

            /*
             * Wrapped error logging function.
             * @param {string} msg Message to log.
             */
            var error = function(msg) {
                if (window.console && window.console.error) {
                    window.console.error(msg);
                } else {
                    log(msg);
                }
            };

            /*
             * Which arguements are enums.
             * @type {!Object.<number, string>}
             */
            var glValidEnumContexts = {

                // Generic setters and getters

                'enable': { 0:true },
                'disable': { 0:true },
                'getParameter': { 0:true },

                // Rendering

                'drawArrays': { 0:true },
                'drawElements': { 0:true, 2:true },

                // Shaders

                'createShader': { 0:true },
                'getShaderParameter': { 1:true },
                'getProgramParameter': { 1:true },

                // Vertex attributes

                'getVertexAttrib': { 1:true },
                'vertexAttribPointer': { 2:true },

                // Textures

                'bindTexture': { 0:true },
                'activeTexture': { 0:true },
                'getTexParameter': { 0:true, 1:true },
                'texParameterf': { 0:true, 1:true },
                'texParameteri': { 0:true, 1:true, 2:true },
                'texImage2D': { 0:true, 2:true, 6:true, 7:true },
                'texSubImage2D': { 0:true, 6:true, 7:true },
                'copyTexImage2D': { 0:true, 2:true },
                'copyTexSubImage2D': { 0:true },
                'generateMipmap': { 0:true },

                // Buffer objects

                'bindBuffer': { 0:true },
                'bufferData': { 0:true, 2:true },
                'bufferSubData': { 0:true },
                'getBufferParameter': { 0:true, 1:true },

                // Renderbuffers and framebuffers

                'pixelStorei': { 0:true, 1:true },
                'readPixels': { 4:true, 5:true },
                'bindRenderbuffer': { 0:true },
                'bindFramebuffer': { 0:true },
                'checkFramebufferStatus': { 0:true },
                'framebufferRenderbuffer': { 0:true, 1:true, 2:true },
                'framebufferTexture2D': { 0:true, 1:true, 2:true },
                'getFramebufferAttachmentParameter': { 0:true, 1:true, 2:true },
                'getRenderbufferParameter': { 0:true, 1:true },
                'renderbufferStorage': { 0:true, 1:true },

                // Frame buffer operations (clear, blend, depth test, stencil)

                'clear': { 0:true },
                'depthFunc': { 0:true },
                'blendFunc': { 0:true, 1:true },
                'blendFuncSeparate': { 0:true, 1:true, 2:true, 3:true },
                'blendEquation': { 0:true },
                'blendEquationSeparate': { 0:true, 1:true },
                'stencilFunc': { 0:true },
                'stencilFuncSeparate': { 0:true, 1:true },
                'stencilMaskSeparate': { 0:true },
                'stencilOp': { 0:true, 1:true, 2:true },
                'stencilOpSeparate': { 0:true, 1:true, 2:true, 3:true },

                // Culling

                'cullFace': { 0:true },
                'frontFace': { 0:true }
            };

            /*
             * Map of numbers to names.
             * @type {Object}
             */
            var glEnums = null;

            /*
             * Initializes this module. Safe to call more than once.
             * @param {!WebGLRenderingContext} ctx A WebGL context. If
             *    you have more than one context it doesn't matter which one
             *    you pass in, it is only used to pull out constants.
             */
            function init(ctx) {
                if (glEnums == null) {
                    glEnums = { };
                    for (var propertyName in ctx) {
                        if (typeof ctx[propertyName] == 'number') {
                            glEnums[ctx[propertyName]] = propertyName;
                        }
                    }
                }
            }

            /*
             * Checks the utils have been initialized.
             */
            function checkInit() {
                if (glEnums == null) {
                    throw 'WebGLDebugUtils.init(ctx) not called';
                }
            }

            /*
             * Returns true or false if value matches any WebGL enum
             * @param {*} value Value to check if it might be an enum.
             * @return {boolean} True if value matches one of the WebGL defined enums
             */
            function mightBeEnum(value) {
                checkInit();
                return (glEnums[value] !== undefined);
            }

            /*
             * Gets an string version of an WebGL enum.
             *
             * Example:
             * @example
             *     var str = WebGLDebugUtil.glEnumToString(ctx.getError());
             *
             * @param {number} value Value to return an enum for
             * @return {string} The string version of the enum.
             */
            function glEnumToString(value) {
                checkInit();
                var name = glEnums[value];
                return (name !== undefined) ? name :
                    ("*UNKNOWN WebGL ENUM (0x" + value.toString(16) + ")");
            }

            /*
             * Returns the string version of a WebGL argument.
             * Attempts to convert enum arguments to strings.
             * @param {string} functionName the name of the WebGL function.
             * @param {number} argumentIndx the index of the argument.
             * @param {*} value The value of the argument.
             * @return {string} The value as a string.
             */
            function glFunctionArgToString(functionName, argumentIndex, value) {
                var funcInfo = glValidEnumContexts[functionName];
                if (funcInfo !== undefined) {
                    if (funcInfo[argumentIndex]) {
                        return glEnumToString(value);
                    }
                }
                if (value === null) {
                    return "null";
                } else if (value === undefined) {
                    return "undefined";
                } else {
                    return value.toString();
                }
            }

            /*
             * Converts the arguments of a WebGL function to a string.
             * Attempts to convert enum arguments to strings.
             *
             * @param {string} functionName the name of the WebGL function.
             * @param {number} args The arguments.
             * @return {string} The arguments as a string.
             */
            function glFunctionArgsToString(functionName, args) {
                // apparently we can't do args.join(",");
                var argStr = "";
                for (var ii = 0; ii < args.length; ++ii) {
                    argStr += ((ii == 0) ? '' : ', ') +
                        glFunctionArgToString(functionName, ii, args[ii]);
                }
                return argStr;
            };


            function makePropertyWrapper(wrapper, original, propertyName) {
                //log("wrap prop: " + propertyName);
                wrapper.__defineGetter__(propertyName, function() {
                    return original[propertyName];
                });
                // TODO(gmane): this needs to handle properties that take more than
                // one value?
                wrapper.__defineSetter__(propertyName, function(value) {
                    //log("set: " + propertyName);
                    original[propertyName] = value;
                });
            }

            // Makes a function that calls a function on another object.
            function makeFunctionWrapper(original, functionName) {
                //log("wrap fn: " + functionName);
                var f = original[functionName];
                return function() {
                    //log("call: " + functionName);
                    var result = f.apply(original, arguments);
                    return result;
                };
            }

            /*
             * Given a WebGL context returns a wrapped context that calls
             * gl.getError after every command and calls a function if the
             * result is not gl.NO_ERROR.
             *
             * @param {!WebGLRenderingContext} ctx The webgl context to
             *        wrap.
             * @param {!function(err, funcName, args): void} opt_onErrorFunc
             *        The function to call when gl.getError returns an
             *        error. If not specified the default function calls
             *        console.log with a message.
             * @param {!function(funcName, args): void} opt_onFunc The
             *        function to call when each webgl function is called.
             *        You can use this to log all calls for example.
             */
            function makeDebugContext(ctx, opt_onErrorFunc, opt_onFunc) {
                init(ctx);
                opt_onErrorFunc = opt_onErrorFunc || function(err, functionName, args) {
                    // apparently we can't do args.join(",");
                    var argStr = "";
                    for (var ii = 0; ii < args.length; ++ii) {
                        argStr += ((ii == 0) ? '' : ', ') +
                            glFunctionArgToString(functionName, ii, args[ii]);
                    }
                    error("WebGL error "+ glEnumToString(err) + " in "+ functionName +
                        "(" + argStr + ")");
                };

                // Holds booleans for each GL error so after we get the error ourselves
                // we can still return it to the client app.
                var glErrorShadow = { };

                // Makes a function that calls a WebGL function and then calls getError.
                function makeErrorWrapper(ctx, functionName) {
                    return function() {
                        if (opt_onFunc) {
                            opt_onFunc(functionName, arguments);
                        }
                        var result = ctx[functionName].apply(ctx, arguments);
                        var err = ctx.getError();
                        if (err != 0) {
                            glErrorShadow[err] = true;
                            opt_onErrorFunc(err, functionName, arguments);
                        }
                        return result;
                    };
                }

                // Make a an object that has a copy of every property of the WebGL context
                // but wraps all functions.
                var wrapper = {};
                for (var propertyName in ctx) {
                    if (typeof ctx[propertyName] == 'function') {
                        wrapper[propertyName] = makeErrorWrapper(ctx, propertyName);
                    } else {
                        makePropertyWrapper(wrapper, ctx, propertyName);
                    }
                }

                // Override the getError function with one that returns our saved results.
                wrapper.getError = function() {
                    for (var err in glErrorShadow) {
                        if (glErrorShadow.hasOwnProperty(err)) {
                            if (glErrorShadow[err]) {
                                glErrorShadow[err] = false;
                                return err;
                            }
                        }
                    }
                    return ctx.NO_ERROR;
                };

                return wrapper;
            }

            function resetToInitialState(ctx) {
                var numAttribs = ctx.getParameter(ctx.MAX_VERTEX_ATTRIBS);
                var tmp = ctx.createBuffer();
                ctx.bindBuffer(ctx.ARRAY_BUFFER, tmp);
                for (var ii = 0; ii < numAttribs; ++ii) {
                    ctx.disableVertexAttribArray(ii);
                    ctx.vertexAttribPointer(ii, 4, ctx.FLOAT, false, 0, 0);
                    ctx.vertexAttrib1f(ii, 0);
                }
                ctx.deleteBuffer(tmp);

                var numTextureUnits = ctx.getParameter(ctx.MAX_TEXTURE_IMAGE_UNITS);
                for (var ii = 0; ii < numTextureUnits; ++ii) {
                    ctx.activeTexture(ctx.TEXTURE0 + ii);
                    ctx.bindTexture(ctx.TEXTURE_CUBE_MAP, null);
                    ctx.bindTexture(ctx.TEXTURE_2D, null);
                }

                ctx.activeTexture(ctx.TEXTURE0);
                ctx.useProgram(null);
                ctx.bindBuffer(ctx.ARRAY_BUFFER, null);
                ctx.bindBuffer(ctx.ELEMENT_ARRAY_BUFFER, null);
                ctx.bindFramebuffer(ctx.FRAMEBUFFER, null);
                ctx.bindRenderbuffer(ctx.RENDERBUFFER, null);
                ctx.disable(ctx.BLEND);
                ctx.disable(ctx.CULL_FACE);
                ctx.disable(ctx.DEPTH_TEST);
                ctx.disable(ctx.DITHER);
                ctx.disable(ctx.SCISSOR_TEST);
                ctx.blendColor(0, 0, 0, 0);
                ctx.blendEquation(ctx.FUNC_ADD);
                ctx.blendFunc(ctx.ONE, ctx.ZERO);
                ctx.clearColor(0, 0, 0, 0);
                ctx.clearDepth(1);
                ctx.clearStencil(-1);
                ctx.colorMask(true, true, true, true);
                ctx.cullFace(ctx.BACK);
                ctx.depthFunc(ctx.LESS);
                ctx.depthMask(true);
                ctx.depthRange(0, 1);
                ctx.frontFace(ctx.CCW);
                ctx.hint(ctx.GENERATE_MIPMAP_HINT, ctx.DONT_CARE);
                ctx.lineWidth(1);
                ctx.pixelStorei(ctx.PACK_ALIGNMENT, 4);
                ctx.pixelStorei(ctx.UNPACK_ALIGNMENT, 4);
                ctx.pixelStorei(ctx.UNPACK_FLIP_Y_WEBGL, false);
                ctx.pixelStorei(ctx.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
                // TODO: Delete this IF.
                if (ctx.UNPACK_COLORSPACE_CONVERSION_WEBGL) {
                    ctx.pixelStorei(ctx.UNPACK_COLORSPACE_CONVERSION_WEBGL, ctx.BROWSER_DEFAULT_WEBGL);
                }
                ctx.polygonOffset(0, 0);
                ctx.sampleCoverage(1, false);
                ctx.scissor(0, 0, ctx.canvas.width, ctx.canvas.height);
                ctx.stencilFunc(ctx.ALWAYS, 0, 0xFFFFFFFF);
                ctx.stencilMask(0xFFFFFFFF);
                ctx.stencilOp(ctx.KEEP, ctx.KEEP, ctx.KEEP);
                ctx.viewport(0, 0, ctx.canvas.width, ctx.canvas.height);
                ctx.clear(ctx.COLOR_BUFFER_BIT | ctx.DEPTH_BUFFER_BIT | ctx.STENCIL_BUFFER_BIT);

                // TODO: This should NOT be needed but Firefox fails with 'hint'
                while(ctx.getError());
            }

            function makeLostContextSimulatingCanvas(canvas) {
                var unwrappedContext_;
                var wrappedContext_;
                var onLost_ = [];
                var onRestored_ = [];
                var wrappedContext_ = {};
                var contextId_ = 1;
                var contextLost_ = false;
                var resourceId_ = 0;
                var resourceDb_ = [];
                var numCallsToLoseContext_ = 0;
                var numCalls_ = 0;
                var canRestore_ = false;
                var restoreTimeout_ = 0;

                // Holds booleans for each GL error so can simulate errors.
                var glErrorShadow_ = { };

                canvas.getContext = function(f) {
                    return function() {
                        var ctx = f.apply(canvas, arguments);
                        // Did we get a context and is it a WebGL context?
                        if (ctx instanceof WebGLRenderingContext) {
                            if (ctx != unwrappedContext_) {
                                if (unwrappedContext_) {
                                    throw "got different context"
                                }
                                unwrappedContext_ = ctx;
                                wrappedContext_ = makeLostContextSimulatingContext(unwrappedContext_);
                            }
                            return wrappedContext_;
                        }
                        return ctx;
                    }
                }(canvas.getContext);

                function wrapEvent(listener) {
                    if (typeof(listener) == "function") {
                        return listener;
                    } else {
                        return function(info) {
                            listener.handleEvent(info);
                        }
                    }
                }

                var addOnContextLostListener = function(listener) {
                    onLost_.push(wrapEvent(listener));
                };

                var addOnContextRestoredListener = function(listener) {
                    onRestored_.push(wrapEvent(listener));
                };


                function wrapAddEventListener(canvas) {
                    var f = canvas.addEventListener;
                    canvas.addEventListener = function(type, listener, bubble) {
                        switch (type) {
                        case 'webglcontextlost':
                            addOnContextLostListener(listener);
                            break;
                        case 'webglcontextrestored':
                            addOnContextRestoredListener(listener);
                            break;
                        default:
                            f.apply(canvas, arguments);
                        }
                    };
                }

                wrapAddEventListener(canvas);

                canvas.loseContext = function() {
                    if (!contextLost_) {
                        contextLost_ = true;
                        numCallsToLoseContext_ = 0;
                        ++contextId_;
                        while (unwrappedContext_.getError());
                        clearErrors();
                        glErrorShadow_[unwrappedContext_.CONTEXT_LOST_WEBGL] = true;
                        var event = makeWebGLContextEvent("context lost");
                        var callbacks = onLost_.slice();
                        setTimeout(function() {
                            //log("numCallbacks:" + callbacks.length);
                            for (var ii = 0; ii < callbacks.length; ++ii) {
                                //log("calling callback:" + ii);
                                callbacks[ii](event);
                            }
                            if (restoreTimeout_ >= 0) {
                                setTimeout(function() {
                                    canvas.restoreContext();
                                }, restoreTimeout_);
                            }
                        }, 0);
                    }
                };

                canvas.restoreContext = function() {
                    if (contextLost_) {
                        if (onRestored_.length) {
                            setTimeout(function() {
                                if (!canRestore_) {
                                    throw "can not restore. webglcontestlost listener did not call event.preventDefault";
                                }
                                freeResources();
                                resetToInitialState(unwrappedContext_);
                                contextLost_ = false;
                                numCalls_ = 0;
                                canRestore_ = false;
                                var callbacks = onRestored_.slice();
                                var event = makeWebGLContextEvent("context restored");
                                for (var ii = 0; ii < callbacks.length; ++ii) {
                                    callbacks[ii](event);
                                }
                            }, 0);
                        }
                    }
                };

                canvas.loseContextInNCalls = function(numCalls) {
                    if (contextLost_) {
                        throw "You can not ask a lost context to be lost";
                    }
                    numCallsToLoseContext_ = numCalls_ + numCalls;
                };

                canvas.getNumCalls = function() {
                    return numCalls_;
                };

                canvas.setRestoreTimeout = function(timeout) {
                    restoreTimeout_ = timeout;
                };

                function isWebGLObject(obj) {
                    //return false;
                    return (obj instanceof WebGLBuffer ||
                        obj instanceof WebGLFramebuffer ||
                        obj instanceof WebGLProgram ||
                        obj instanceof WebGLRenderbuffer ||
                        obj instanceof WebGLShader ||
                        obj instanceof WebGLTexture);
                }

                function checkResources(args) {
                    for (var ii = 0; ii < args.length; ++ii) {
                        var arg = args[ii];
                        if (isWebGLObject(arg)) {
                            return arg.__webglDebugContextLostId__ == contextId_;
                        }
                    }
                    return true;
                }

                function clearErrors() {
                    var k = Object.keys(glErrorShadow_);
                    for (var ii = 0; ii < k.length; ++ii) {
                        delete glErrorShadow_[k];
                    }
                }

                function loseContextIfTime() {
                    ++numCalls_;
                    if (!contextLost_) {
                        if (numCallsToLoseContext_ == numCalls_) {
                            canvas.loseContext();
                        }
                    }
                }

                // Makes a function that simulates WebGL when out of context.
                function makeLostContextFunctionWrapper(ctx, functionName) {
                    var f = ctx[functionName];
                    return function() {
                        // log("calling:" + functionName);
                        // Only call the functions if the context is not lost.
                        loseContextIfTime();
                        if (!contextLost_) {
                            //if (!checkResources(arguments)) {
                            //  glErrorShadow_[wrappedContext_.INVALID_OPERATION] = true;
                            //  return;
                            //}
                            try{
                                var result = f.apply(ctx, arguments);
                                return result;
                            }catch (e){
                                debugger;
                                return null;
                            }
                        }
                    };
                }

                function freeResources() {
                    for (var ii = 0; ii < resourceDb_.length; ++ii) {
                        var resource = resourceDb_[ii];
                        if (resource instanceof WebGLBuffer) {
                            unwrappedContext_.deleteBuffer(resource);
                        } else if (resource instanceof WebGLFramebuffer) {
                            unwrappedContext_.deleteFramebuffer(resource);
                        } else if (resource instanceof WebGLProgram) {
                            unwrappedContext_.deleteProgram(resource);
                        } else if (resource instanceof WebGLRenderbuffer) {
                            unwrappedContext_.deleteRenderbuffer(resource);
                        } else if (resource instanceof WebGLShader) {
                            unwrappedContext_.deleteShader(resource);
                        } else if (resource instanceof WebGLTexture) {
                            unwrappedContext_.deleteTexture(resource);
                        }
                    }
                }

                function makeWebGLContextEvent(statusMessage) {
                    return {
                        statusMessage: statusMessage,
                        preventDefault: function() {
                            canRestore_ = true;
                        }
                    };
                }

                return canvas;

                function makeLostContextSimulatingContext(ctx) {
                    // copy all functions and properties to wrapper
                    for (var propertyName in ctx) {
                        if (typeof ctx[propertyName] == 'function') {
                            wrappedContext_[propertyName] = makeLostContextFunctionWrapper(
                                ctx, propertyName);
                        } else {
                            makePropertyWrapper(wrappedContext_, ctx, propertyName);
                        }
                    }

                    // Wrap a few functions specially.
                    wrappedContext_.getError = function() {
                        loseContextIfTime();
                        if (!contextLost_) {
                            var err;
                            while (err = unwrappedContext_.getError()) {
                                glErrorShadow_[err] = true;
                            }
                        }
                        for (var err in glErrorShadow_) {
                            if (glErrorShadow_[err]) {
                                delete glErrorShadow_[err];
                                return err;
                            }
                        }
                        return wrappedContext_.NO_ERROR;
                    };

                    var creationFunctions = [
                        "createBuffer",
                        "createFramebuffer",
                        "createProgram",
                        "createRenderbuffer",
                        "createShader",
                        "createTexture"
                    ];
                    for (var ii = 0; ii < creationFunctions.length; ++ii) {
                        var functionName = creationFunctions[ii];
                        wrappedContext_[functionName] = function(f) {
                            return function() {
                                loseContextIfTime();
                                if (contextLost_) {
                                    return null;
                                }
                                var obj = f.apply(ctx, arguments);
                                obj.__webglDebugContextLostId__ = contextId_;
                                resourceDb_.push(obj);
                                return obj;
                            };
                        }(ctx[functionName]);
                    }

                    var functionsThatShouldReturnNull = [
                        "getActiveAttrib",
                        "getActiveUniform",
                        "getBufferParameter",
                        "getContextAttributes",
                        "getAttachedShaders",
                        "getFramebufferAttachmentParameter",
                        "getParameter",
                        "getProgramParameter",
                        "getProgramInfoLog",
                        "getRenderbufferParameter",
                        "getShaderParameter",
                        "getShaderInfoLog",
                        "getShaderSource",
                        "getTexParameter",
                        "getUniform",
                        "getUniformLocation",
                        "getVertexAttrib"
                    ];
                    for (var ii = 0; ii < functionsThatShouldReturnNull.length; ++ii) {
                        var functionName = functionsThatShouldReturnNull[ii];
                        wrappedContext_[functionName] = function(f) {
                            return function() {
                                loseContextIfTime();
                                if (contextLost_) {
                                    return null;
                                }
                                return f.apply(ctx, arguments);
                            }
                        }(wrappedContext_[functionName]);
                    }

                    var isFunctions = [
                        "isBuffer",
                        "isEnabled",
                        "isFramebuffer",
                        "isProgram",
                        "isRenderbuffer",
                        "isShader",
                        "isTexture"
                    ];
                    for (var ii = 0; ii < isFunctions.length; ++ii) {
                        var functionName = isFunctions[ii];
                        wrappedContext_[functionName] = function(f) {
                            return function() {
                                loseContextIfTime();
                                if (contextLost_) {
                                    return false;
                                }
                                return f.apply(ctx, arguments);
                            }
                        }(wrappedContext_[functionName]);
                    }

                    wrappedContext_.checkFramebufferStatus = function(f) {
                        return function() {
                            loseContextIfTime();
                            if (contextLost_) {
                                return wrappedContext_.FRAMEBUFFER_UNSUPPORTED;
                            }
                            return f.apply(ctx, arguments);
                        };
                    }(wrappedContext_.checkFramebufferStatus);

                    wrappedContext_.getAttribLocation = function(f) {
                        return function() {
                            loseContextIfTime();
                            if (contextLost_) {
                                return -1;
                            }
                            return f.apply(ctx, arguments);
                        };
                    }(wrappedContext_.getAttribLocation);

                    wrappedContext_.getVertexAttribOffset = function(f) {
                        return function() {
                            loseContextIfTime();
                            if (contextLost_) {
                                return 0;
                            }
                            return f.apply(ctx, arguments);
                        };
                    }(wrappedContext_.getVertexAttribOffset);

                    wrappedContext_.isContextLost = function() {
                        return contextLost_;
                    };

                    return wrappedContext_;
                }
            }

            return {
                /**
                 * Initializes this module. Safe to call more than once.
                 *
                 * @method init
                 * @param {!WebGLRenderingContext} ctx A WebGL context. If
                 *    you have more than one context it doesn't matter which one
                 *    you pass in, it is only used to pull out constants.
                 */
                'init': init,

                /**
                 * Returns true or false if value matches any WebGL enum
                 *
                 * @method mightBeEnum
                 * @param {*} value Value to check if it might be an enum.
                 * @return {boolean} True if value matches one of the WebGL defined enums
                 */
                'mightBeEnum': mightBeEnum,

                /**
                 * Gets an string version of an WebGL enum.
                 *
                 * @example
                 *     WebGLDebugUtil.init(ctx);
                 *     var str = WebGLDebugUtil.glEnumToString(ctx.getError());
                 *
                 * @method glFunctionArgToString
                 * @param {number} value Value to return an enum for
                 * @return {string} The string version of the enum.
                 */
                'glEnumToString': glEnumToString,

                /**
                 * Converts the argument of a WebGL function to a string.
                 * Attempts to convert enum arguments to strings.
                 *
                 * @example
                 *     WebGLDebugUtil.init(ctx);
                 *     var str = WebGLDebugUtil.glFunctionArgToString('bindTexture', 0, gl.TEXTURE_2D);
                 *
                 * would return 'TEXTURE_2D'
                 *
                 * @method glFunctionArgToString
                 * @param {string} functionName the name of the WebGL function.
                 * @param {number} argumentIndx the index of the argument.
                 * @param {*} value The value of the argument.
                 * @return {string} The value as a string.
                 */
                'glFunctionArgToString': glFunctionArgToString,

                /**
                 * Converts the arguments of a WebGL function to a string.
                 * Attempts to convert enum arguments to strings.
                 *
                 * @method glFunctionArgsToString
                 * @param {string} functionName the name of the WebGL function.
                 * @param {number} args The arguments.
                 * @return {string} The arguments as a string.
                 */
                'glFunctionArgsToString': glFunctionArgsToString,

                /**
                 * Given a WebGL context returns a wrapped context that calls
                 * gl.getError after every command and calls a function if the
                 * result is not NO_ERROR.
                 *
                 * You can supply your own function if you want. For example, if you'd like
                 * an exception thrown on any GL error you could do this
                 *
                 * @example
                 *      function throwOnGLError(err, funcName, args) {
                 *        throw WebGLDebugUtils.glEnumToString(err) +
                 *              " was caused by call to " + funcName;
                 *      };
                 *      ctx = WebGLDebugUtils.makeDebugContext(
                 *          canvas.getContext("webgl"), throwOnGLError);
                 *
                 * @method makeDebugContext
                 * @param {!WebGLRenderingContext} ctx The webgl context to wrap.
                 * @param {!function(err, funcName, args): void} opt_onErrorFunc The function
                 *     to call when gl.getError returns an error. If not specified the default
                 *     function calls console.log with a message.
                 * @param {!function(funcName, args): void} opt_onFunc The
                 *     function to call when each webgl function is called. You
                 *     can use this to log all calls for example.
                 */
                'makeDebugContext': makeDebugContext,

                /**
                 * Given a canvas element returns a wrapped canvas element that will
                 * simulate lost context. The canvas returned adds the following functions.
                 *
                 * loseContext:
                 *   simulates a lost context event.
                 *
                 * restoreContext:
                 *   simulates the context being restored.
                 *
                 * lostContextInNCalls:
                 *   loses the context after N gl calls.
                 *
                 * getNumCalls:
                 *   tells you how many gl calls there have been so far.
                 *
                 * setRestoreTimeout:
                 *   sets the number of milliseconds until the context is restored
                 *   after it has been lost. Defaults to 0. Pass -1 to prevent
                 *   automatic restoring.
                 *
                 * @method makeLostContextSimulatingCanvas
                 * @param {!Canvas} canvas The canvas element to wrap.
                 */
                'makeLostContextSimulatingCanvas': makeLostContextSimulatingCanvas,

                /**
                 * Resets a context to the initial state.
                 * @method resetToInitialState
                 * @param {!WebGLRenderingContext} ctx The webgl context to
                 *     reset.
                 */
                'resetToInitialState': resetToInitialState
            };

        }();
    }
});