the old republic’s object model pipeline

Rob GalanakisSenior Technical Artist

Bioware Austinrgalanakis@bioware.com

the old republic’sobject model pipeline

ovERviEW

exAmPLe piPELiNeA typical pipeline is thought of as…

exAmPLe piPELiNeA more accurate pipeline would be…

dEFiNiTion• Pipeline is the data flow from

conception to game implementation (and beyond)

• Greater than sum of parts– Not only art or assets– Not just exporters– Not just tools

dEFiNiTion

dEFiNiTion

wHat is “dATA”?Well, data is what gives an engineer his power. It's an informationfield created by all things. It surrounds them andpenetrates them. It binds the pipeline together.

-Obi Wan Kenobi(well, close enough, anyway)

exAmPLe piPELiNe

oMP CoNcEPTSIt isn’t art or content, it is DATA!

oMP CoNcEPTS• If it is data, you can represent it in

code.• If you can code it, you can make it an

object.• If you can make it an object, it can

handle itself.– The object knows what to do with itself

and the programs just use the object

oMP CoNcEPTS• 2 main groups of objects• Wrapper Object– The logical layer for manipulating a file’s

contents• Information Object– For Asset Management– Abstracted information describing

content (tags, attributes, file paths, etc.– Inputting the info is up to you

oop pRiNciPLeS

Encapsulation

Inheritance Polymorphism

OOP

encapsulation• “Expose only a certain set of

members to client”• Any data can be encapsulated–Wrap binary files with XML– Custom ascii parsers

• All save/load/export logic on class– Applications work with objects, no direct

read/write of data

encapsulation

iNHERiTANCe• “Subclass inherits code and behavior

of base class”• Group asset management behaviors– Skeletons and meshes are models• Share ‘ModelFilename’ property, but differ in

implementation

iNHERiTANCe

polyMoRPHiSM• “Behavior depends on type”– ‘ContentFilename’ varies between types.– Call ‘ExportModel’ to export the model

according to type, whether static, dynamic, or skeleton model.

– Call ‘ExportXml’ to export metadata, etc.

examples and Test Cases• Object libraries– Binary Wrappers– Xml Wrappers– Ascii Wrappers

• Practical applications– Content-side– Game-side

• Other tips

wRAP Binary: siDECAr• Wraps binary formats into C#/Xml• Allows easy access and manipulation

from external tools–Write tools entirely outside of your 3D

app that directly manipulate it– Code complex functionality once, call it

generically

Tips: siDECAr• Load and apply what’s needed• Plug-ins for non-universal scene info– Keep code portable between projects

• Property dictionaries and Reflection– Serialize loads of random data

Tips: siDECArScooter.Lame, boring,interchangeable

Sidecar. You want to keep this. So much awesome.

wRAP xML• Update format, all files write out

correctly– Update your definitions in one place,

don’t reverse-engineer into exporters• Export from many places• Enums provide valid values

Tips: xML fiLe wRAPPERS• Use XmlSerialization if possible– Use custom ToXml/LoadFromXml if not

• Use .NET’s System.Xml as design for wrapper

wrap aSCii• Custom Save/Load methods for ascii

files– Inherently less robust than Xml

• Auto-convert to/from binary where supported

• Otherwise the same as Xml wrappers

Common exporter• Exporters or tools identify file types passed in and

what to do with them (drag and drop exporters accepting any file type)

Game

gAME oBJECT CoNNECTion

auDiTiNG coNTENT

Tip: partition pipelines• Do not try to develop a single

scheme or system• Focus on allowing communication

and interaction between systems– Needs of certain systems (content vs.

game) fundamentally different

pairing and sharing• Shared data in a database, paired

data in Xml– If you don’t have a DB, get one!– Learn basic SQL and maybe use an ORM

wrap it up• If you need to read it, wrap it–Why not wrap shaders?– Don’t forget existing object models may

exist (Visual Studio projects)

interconnectedness

interconnectedness

mAGNuM oPuS

rEFERENCES• www.tech-artists.org– Forums, wiki, blog

• irc.freenode.net–#techart

• msdn.microsoft.com– System.Xml, System.Xml.Serialization, XPath,

System.Linq• Special thanks to advisory board members Steve

T. and Jeff H.

quESTions?