RE: XML was RE: [GD-General] RE: A portable preferences library

[Gareth L. <GL...@cl...>]

Hopefully you aren't building a mesh from that at run time ? 

XML is good, XML is great. But please tell me that you aren't considering
having mullion polygon meshes in text format ready to be parsed at runtime ?


On a side note, those of you with the 'luck' to work on pc games, you can
just use the msxml parser, which is pretty fully featured.

> -----Original Message-----
> From: Jorrit Tyberghein [mailto:Jor...@uz...]
> Sent: 16 December 2003 12:14
> To: gam...@li...
> Subject: Re: XML was RE: [GD-General] RE: A portable 
> preferences library
> 
> 
> Alen Ladavac wrote:
> 
> >>We use XML a lot in Crystal Space (http://crystal.sf.net). 
> It does tend
> >>to give very
> >>big files but we also found that it doesn't matter.
> >>    
> >>
> >
> >Just how big that is? Can you please compare size of a mesh 
> in XML format to
> >the same mesh in, say, .3ds or .lwo?
> >  
> >
> I didn't make the map files so I don't have any of the model 
> files that
> were used but I can show you an example of a simple mesh in CS:
> 
>     <meshobj name="cube">
>        <plugin>thing</plugin>
>        <params>
>           <v x="-1" y="0" z="1" />
>           <v x="0" y="0" z="1" />
>           ... (more vertices follow)
>           <material>brick</material>
>           <p> <v>0</v> <v>1</v> <v>2</v> </p>
>           <p> <v>3</v> <v>2</v> <v>4</v> <v>5</v> </p>
>           ... (more polygons follow)
>        </params>
>     </meshobj>
> 
> So this is indeed pretty verbose.
> 
> >  
> >
> >>CS supports reading
> >>from ZIP files
> >>so map files are usually placed in compressed archives. XML 
> compresses very
> >>well (due to the high redundancy) so the size disadvantage 
> nearly completely
> >>disappears in that case.
> >>    
> >>
> >
> >Can you also please compare size of a zipped XML mesh and a 
> zipped .3ds, or
> >.lwo or similar format of the same mesh?
> >  
> >
> Sorry. Don't have the needed models to do that.
> 
> >Also, in case that zipping really does remove the redundancy 
> well enough to
> >allow us to ignore the size difference, did you check your 
> effective loading
> >throughput? Meaning how much MB/sec can you read from the 
> disk. To make sure
> >that the parser is not slowing your loading. Ideally, you 
> should be limited by
> >the transfer rate of the disk, not by the CPU.
> >  
> >
> The PlaneShift game (made with CS) has about 25 megabytes 
> (uncompressed) 
> of XML files (aggregated
> in four big files) of level data. On my Linux system at home 
> (an Athlon 
> XP2000) the levels load
> in about 16-20 seconds. That includes the following operations:
>     - Extracting the XML data from the ZIP.
>     - Parsing of XML.
>     - Creation of all objects.
>     - Loading of all textures used in the levels and 
> preparing them for 
> use with OpenGL.
>     - Creation of the kdtree for the visibility culler.
>     - Loading of the lightmap data for the 100000 polygons 
> that are in 
> those levels.
>     - Creation of oriented bounding boxes for collision 
> detection (this 
> is the most
>       time consuming operation of all things mentioned here).
> 
> I don't have seperate numbers for XML parsing but it is a relatively 
> small part
> of the entire thing. Of course this is done using a hand-made 
> XML parser 
> which
> is very lean and mean and is optimized specifically towards reading.
> 
> Greetings,
> 
> 
> 
> 
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