Chris Hargrove
Sr. Programmer
Legend Entertainment
I'll clarify a bit of what Matthias said.
U2 uses our own model system, known as Golem. It is an external library and tool set, which is independent of the Unreal engine. U2 just happens to be the first application that supports using it.
The primary editing tool for working with Golem models is called Golem Studio (working title). It's a standalone app with capabilities for creating and manipulating models, and viewing them within a D3D-based render window that uses virtually the same pipeline that the application (Unreal 2) uses, so you can get a feel for how your model will look. This includes animations, material settings (with multitexture support and a lot of other color and blending controls), and so forth.
Since Golem is a standalone thing, textures used within the tool are loaded from external files, not from Unreal texture packages (.utx files). However, the game does use Unreal packages, and this conflict might seem to indicate that one would need to manually duplicate textures; one inside a package and one outside. To avoid this, we provide a process where a .utx can be quickly and automatically generated from the texture files (dds, tga, etc) within the Golem workspace tree. So when Matt said that the system doesn't use .utx packages anymore, he's correct... but the game still needs them, so we make the conversion step as painless as possible.
Be aware though that I am looking into the possibility of allowing .utx textures to be loaded within the tool as well (to potentially prevent needing any duplicates at all), so the details of this step may change between now and the time we ship. But whichever approach we end up settling on, painlessness is definitely a top priority.
Netdevil said:
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In any case, i'm more interested in the model format since my program needs to directly read the model from its package to preview the skins.
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Bear with me, this may sound a bit complicated.
Golem's .gem model file format is extensively documented so if you want to import or export to/from it, you'll be able to do so. Some facilities for making this easier will be available via the library itself if you code in C++, using the class-based plugin SDK. For example, the .psk/.psa importer to bring in data from Epic's skeletal files is actually just a plugin; it's not tied to the library, and additional plugins can be dropped in at will.
So if you want to import/export data from Golem with Golem itself, you can do so via the SDK. If you want to work with .gem files externally on your own, the format is documented so you can do that too. Be aware though that the former may be simpler than the latter, due to the various kinds of data that .gem files support. I supply documentation for the format of all standard gem objects, but plugin authors could potentially add their own additional data (to be used by any new entity script abilities they've added... i'll explain those later), and it's up to them whether they want to document those objects or not. But many folks won't need to add data like that, since some simple custom information can be added in a standardized way via integer/float/string/objref attributes, which all gem objects support (and the format of these is documented... think of them just like key/value pairs that can be hung off of any gem object).
As for the standard gem objects, there are quite a few to handle different chunks of data, such as triangle and vertex lists, texture UV coordinates, material definitions, bone animation sequences, entity blueprints (the backbone of the system; more on these later), and so on. So you'll have your hands full, but the information to help you out should be there.
I'll try to go into greater detail about the system as time goes on and we get closer to release. I also plan to release the .gem file format specification to the public a little before release if possible (once it's in lockdown), so mod/tool people can make any preparations they need. The SDK should be available shortly after the game ships, for those who want to look into making Golem plugins.
Hopefully that's enough info for the time being.
- Chris
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