Posts Tagged ‘kmz’

Very “efficient” DAE parser in papervision 3d

January 22nd, 2009

I’m currently workin on some bigger project, and I needed to load DAE file. It’s known, that papervision3d has DAE parser – so I used it. But when I tried to load a little bigger file ( only 400KB model ), flash thrown 15 seconds timeout exception. The exception was thrown during unpack process. “Wow, flash is so slow, that it can’t unpack 400KB zip in 15 seconds? This sucks” I thought. But later I looked deeper into DAE parser’s code. DAE parser uses KMZ parser, to unpack DAE’s content ( like textures and models ), and then parses XML ( or rather KMZ unpacks and then uses DAE to read model… ). I followed the code ( just like Dexter does ), and studied KMZ parser’s code. And it appears, that KMZ’s parser code, isn’t the most efficient code I’ve ever seen.

Just look @ it:

http://papervision3d.googlecode.com/svn/trunk/as3/trunk/src/org/papervision3d/objects/parsers/KMZ.as

After loading the zip file, it calls “parse” function, which calls “getColladaFromZip”. getColladaFromZip unopacks the zip file:

private function getColladaFromZip( zipFile : ZipFile ) : ByteArray  {
	for(var i:int = 0; i < zipFile.entries.length; i++) {
	    var entry:ZipEntry = zipFile.entries[i];

	    // extract the entry's data from the zip
	    var data:ByteArray = zipFile.getInput(entry);

		if(entry.name.toLowerCase().indexOf(".dae") != -1) {
			return data;
		}
	}
	return null;
}

It unpacks entire file, just to get the “dae” file, and then returns. More – it extracts content ( function “getInput” ) , and then checks if unpacked content is “dae” file, despite the fact, that to check it, we don’t need to unpack anything to check it.

It gets worse later – it unpacks entire file to check how many textures we have in the zip:

private function numTexturesInZip( zipFile : ZipFile ) : uint {
	var count : uint = 0;
	for(var i:int = 0; i < zipFile.entries.length; i++) {
	    var entry:ZipEntry = zipFile.entries[i];

	    // extract the entry's data from the zip
	    var data:ByteArray = zipFile.getInput(entry);

	    if(entry.name.toLowerCase().indexOf(".png") != -1 || entry.name.toLowerCase().indexOf(".jpg") != -1) {
		count++;
	 }
	 }
	return count;
}

Ok, and at the end, in the “parse” function, every file in archive is extracted again, only for purpose of loading textures from this archive.

Reassuming, if you have 1 meg model and several 200 KB textures, KMZ parser extracts geometry 3 times – second time, to count number of textures (?!?) and third, to load textures. Every texture is extrated 3 times too – first time – to ensure that the texture isn’t a model, second – to count it, and finally third time – to load texture. I think that somebody pasted the code of loading zip file from some tutorial and repasted it 3 times :)

I would paste here my code of better KMZ parser, but it’s too integrated with my project, so you’ll have to wait ; p

And I wrote this post, to enlight you people, that when you are using pv3d’s KMZ parser to load zipped DAE, it isn’t the best parser to use.

Tags: , , , , , ,
Posted in flash experiments | Comments (11)