===Parser Interface=Example==Here is an example which you can use to help understand the process: [link here]

The library would then take care following bit of the rest by creating code is a skeleton which you can use as an instanceof their aid to help you write your own parser, call its methods and return a point cloud objectfor XB PointStream.

var Your_Parser_Name = (function() { /* The constructor XBPS will create an instance of your parser and pass in an object with three named properties: start - must occur exactly once. When you call this function, pass in a reference to your parser end - must occur exactly once. When you call this function, pass in a reference to your parser parse - may occur one or many times. When you call this function, pass in a reference to your parser as the first argument and an object as the second argument.  This second object must have variables referencing typed single-dimensional arrays which contain the parsed values. For example, if vertsArray and colsArray were Float32Array arrays, you would call the parse function like this:  var attributes = {}; attributes["ps_Vertex"] = vertsArray; attributes["ps_Color"] = colsArray; parse(thisParser, attributes);  PointStream will create buffers using these values and start rendering them using the built-in shaders. Notice the variable names have been qualified with "ps_". If you are using the XB PointStream built-in shaders, you will need to use these exact variable names. These are the only two variables the built-in shaders read. If your parser reads in vertex normal data, you will need to write your own shaders to handle lighting. */ function Your_Parser_Name(config) { /*Returns the version of this parser.*/ this.__defineGetter__("version", function(){return /*!!*/;}); /*Get the number of parsed points so far.*/ this.__defineGetter__("numParsedPoints", function(){return /*!!*/;}); /*Get the total number of points in the point cloud.*/ this.__defineGetter__("numTotalPoints", function(){return /*!!*/;}); /*Returns the progress of downloading the point cloud between zero and one.*/ this.__defineGetter__("progress", function(){return /*!!*/;}); /*Returns the file size of the resource in bytes.*/ this.__defineGetter__("fileSize", function(){return /*!!*/;}); /*Path = path to the resource */ this.load = function(path){/*!!*/}; } return Your_Parser_Name;}());</pre>

These functions pass the === Sample Parser ===Here is a very simple parser which only reads in vertex data from a file.<pre>/*The following is a very simple parser back written only to the library since the library couldbe used as be working with many parsers simultaneouslyan example of how a user could write a parser for XB PointStream.*/var FOO_Parser = (function() {

function FOO_Parser(config) { var start - must occur exactly once= config.start || function(){}; var parse = config.parse || function(){}; var end = config.end || function(){}; var fileSizeInBytes = 0; var numParsedPoints = 0; var numTotalPoints = 0; var progress = 0; // keep track if onprogress event handler was called to // handle Chrome/WebKit vs. Minefield differences. Has // Minefield will call onprogress zero or many times // Chrome/WebKit will call onprogress one argumentor many times var onProgressCalled = false; var AJAX = null; /* Returns the version of this parser. */ this.__defineGetter__("version", function(){return 0.1;}); /* Get the parser itselfnumber of parsed points so far. */ end - must occur exactly once this. Has one argument__defineGetter__("numParsedPoints", function(){return numParsedPoints;}); /* Get the parser itselftotal number of points in the point cloud. */ this.__defineGetter__("numTotalPoints", function(){ return numTotalPoints;}); parse - may occur /* Get the progress of downloading the point cloud (zero to one or many times-1 if unknown) */ this. Has two arguments__defineGetter__("progress", function(){ return progress;}); /* Returns the parser itself and afile size of the resource in bytes. */ named collection of value types this.__defineGetter__("fileSize", function(){return fileSizeInBytes;});

*/Constructor AJAX = new XMLHttpRequest(obj); AJAX.parser = this;

/*occurs exactly once, when the resource begins to be downloaded */ Begins to load AJAX.onloadstart = function(evt){ start(AJAX.parser); }; /*occurs exactly once, when the resourcefile is done being downloaded */ AJAX.onload = function(evt){ var ascData = AJAX.responseText; var chunk = null;

@param // if the onprogress event didn't get called--we simply got // the file in one go, we can parse from start to finish. if(onProgressCalled === false){String chunk = ascData; } path - path // otherwise the onprogress event was called at least once, // that means we need to get the data from a specific point to resourcethe end.*/ else if(ascData.length - AJAX.lastNewLineIndex > 1){load chunk = ascData.substring(pathAJAX.lastNewLineIndex, ascData.length); }

AJAX.parseChunk = function(chunk){ /*/ this occurs over network connections, but not locally. if(chunk !== ""){ // trim leading and trailing spaces chunk = chunk.replace(/\s+$/,""); Get the version of this parser chunk = chunk.replace(/^\s+/,""); // split on white space chunk = chunk.split(/\s+/); @returns {String} parser version * var numVerts = chunk.length/3; numParsedPoints += numVerts; version var verts = new Float32Array(numVerts * 3);

for(var i = 0, j = 0, len = chunk.length; i < len; i += 3, j += 3){ verts[j] = parseFloat(chunk[i]); verts[j+1] = parseFloat(chunk[i+1]); verts[j+2] = parseFloat(chunk[i+2]); } // XB PointStream expects an object with named/value pairs // which contain the attribute arrays. These must match attribute // names found in the shader parse(AJAX.parser, {"ps_Vertex":verts}); } }; /*On Minefield, this will occur zero or many times On Chrome/WebKit this will occur one or many times */ AJAX.onprogress = function(evt){ if(evt.lengthComputable){ fileSizeInBytes = evt.total; Get the number of points which have been parsed progress = evt.loaded/evt.total; }

/*/ if we have something to actually parse Get the total number of points in the point cloud, including points if(AJAX.responseText){ which have not yet been parsed var ascData = AJAX.responseText;

@returns {Number} // likely stopped getting data in the total number middle of points a line in the resource or file: // 1.079 1.296 9.360 0 0 0 4.307 1.181 5.208\n // 3.163 2.225 6.139 0 0 0 0.6<-1 - stopped here // So find the last known newline. Everything from the last // request to this last newline can be placed in a buffer. var lastNewLineIndex = ascData.lastIndexOf("\n"); AJAX.lastNewLineIndex = lastNewLineIndex; // if the status just changed and we finished downloading the // file, grab everyting until the end. If there is only a bunch // of whitespace, make a note of that and don't bother parsing. if unknown(AJAX.readyState === 4){ var chunk = ascData.substring(AJAX.startOfNextChunk, ascData.length); AJAX.parseChunk(chunk); } // if we still have more data to go else{* //Start of the next chunk starts after the newline. var chunk = ascData.substring(AJAX.startOfNextChunk, lastNewLineIndex + 1); AJAX.startOfNextChunk = lastNewLineIndex + 1; AJAX.parseChunk(chunk); } } }; AJAX.open("GET", path, true); AJAX.send(null); }; } return FOO_Parser;numTotalPoints}());</pre>

/*=== Create your HTML file === Get Create an HTML which includes your parser, the progress of library and the parser, how much it has parsed so fardemo.js script.<pre><html> <head> <script src="foo_parser.js"></script> <script src="xbps.js"></script> <script src="demo.js"></script> </head>

@returns {Number} value between 0 to 1 or -1 if unknown.<body onLoad="start();">* <canvas id="canvas" width="300" height="300"></canvas> progress </body></html></pre>

/*=== Create the Demo.js file === The size of the resource Give XBPS a reference to your parser and tell it what files it can read. In this case, we pass in bytes"foo".

<pre>function start(){ var ps = new PointStream(); ps.setup(document.getElementById('canvas')); ps.registerParser("foo", FOO_Parser); @returns ps.onRender = function render() {Number} the number of bytes in the resource or ps.translate(0, 0, -1 if unknown20); ps.render(acorn); };*/ var acorn = ps.load("pointCloud.foo");fileSize}

The following example demonstrates how XB PointStream XBPS might use

parser = new XYZParserYour_Parser_Name({ start: startCallback, parse: parseCallback, end: finishCallback});