I've been using this a bit to experiment with whatever's packaged in D:OS II and I'm really rather impressed with the scope of what it can do. So far I've extracted the PAKs, and even converted a mesh to get it into Blender and then back into the game.
It
mostly works (er, by which I mean "I can mostly work it") but the one thing I can't get to work is UV maps: somewhere in between converting the mesh to Collada format and then slurping it into Blender (v2.75) the UV is going missing. I suspect it's something I'm doing wrong, especially as 2.75 is a bit of an unknown to me: as much as I hate 2.49's interface, I've resisted changing to something new until I've basically been forced to do so.
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Granny Viewer shows that the UV is there in the original GR2 so I figure I'm using the wrong options somewhere along the line.
For the record, Granny Viewer can't read the newly created GR2, though that's probably because I'm using a really ancient version that appears to be dated 2008.