Unreal 2 Golem (.gem) plugin for Blender.

[VendorX]

Sun, this will be no longer Blender plug-in, because Blender is too limited... I work on C# version - directly dump mesh and animation.

MERRY CHRISTMAS PEOPLES!

[maxdamage]

Originally Posted by VendorX

Sun, this will be no longer Blender plug-in, because Blender is too limited... I work on C# version - directly dump mesh and animation.

MERRY CHRISTMAS PEOPLES!

Any news on it?Would like to get some of the models from Unreal2 but the .gem import plug-in isn't compatible with Blender v2.57b.

Thanks.

[VendorX]

Well... Still working on animations - only bone rotations was left to do. As to the compatibility, i have somewhere updated version to 2.60 - will update download link.

[maxdamage]

Any word on the C++ app?

Thanks.

[AlCapowned]

VendorX, would it help you if you had a few PSK/PSA files and matching Gem files? The Unreal 2 alpha has an animated Aida model and a few weapons with all three file types.

[chargrove]

Hi all! My name is Chris Hargrove; I wrote Golem.

(I may have another account on this forum with my full name, but I lost my login info that a long time ago and I know my email address has changed, but whatever).

Anyway, I first noticed this thread last year in passing, but stumbled onto it again today; I'm stunned and impressed that people have done so much work to reverse-engineer the .gem format! I know some parts of it aren't the easiest to work with from the outside looking in.

It being nearly a decade since I wrote that stuff, I'm pretty sure nobody would care if I gave people format information (that was one of the things we originally intended to do back when I was at Legend)... however "pretty sure" doesn't hold up legally, and the problem is ever since Legend was closed down by Infogrames, I have absolutely no idea who I would have to talk to in order to release information like that. So I apologize profusely for that.

That said, I'm not sure if this exporter project is still happening, but if it is: one thing I *can* tell you is how those 5-byte rotations work, because it's something I wrote long before Golem, and which I've used both before and since then, so it's not tied to that specific implementation and hence no legal concerns there. Since it's something you folks indicated was a bit of a blocking point, I figured I could elucidate it here.

The basic idea is that it's a packed axis & angle, which you can use to put into a quaternion. 5 bytes was enough to encode them both with sufficient precision; I did experiments with 4 bytes but it just looked too jittery. I probably could have gotten into 4 bytes most of the time if I allowed some kind of VBR scheme for the edge cases, but having a fixed-size structure was extremely helpful at runtime (despite the odd size).

Anyway, here's some code for it. I've sanitized it a bit so hopefully I didn't break anything in the process, but hopefully you can figure out what's going on.

BTW, when you see typecasts in there, note that the code is based on a little-endian CPU (such as x86). If you're operating on a big-endian CPU, adjust accordingly.

enum
{
	PACKED_AXIS_SIGNMASK = 0xE00000,
	PACKED_AXIS_XSIGNMASK = 0x800000,
	PACKED_AXIS_YSIGNMASK = 0x400000,
	PACKED_AXIS_ZSIGNMASK = 0x200000,
	PACKED_AXIS_XMASK = 0x1FF800,
	PACKED_AXIS_YMASK = 0x0007FF
};

VECTOR3 UnpackAxis(unsigned long p)
{
	// get the x and y bits
	signed long xBits = (p & PACKED_AXIS_XMASK) >> 11;
	signed long yBits = p & PACKED_AXIS_YMASK;

	// map the numbers into the projection triangle
	if ((xBits + yBits) >= 2047)
	{
		xBits = 2047 - xBits;
		yBits = 2047 - yBits;
	}

	// build vector
	VECTOR3 result;
	result.x = (float)xBits;
	result.y = (float)yBits;
	result.z = (float)(2046 - xBits - yBits);

	// restore sign bits
	if (p & PACKED_AXIS_XSIGNMASK) result.x = -result.x;
	if (p & PACKED_AXIS_YSIGNMASK) result.y = -result.y;
	if (p & PACKED_AXIS_ZSIGNMASK) result.z = -result.z;
	
	// need to post-normalize since there's no normalization table
	float s = 1.f / (float)sqrt(result.x*result.x + result.y*result.y + result.z*result.z);
	result.x *= s;
	result.y *= s;
	result.z *= s;
	return result;
}

QUAT UnpackQuat(unsigned char* fiveBytes)
{
	// extract packed axis and angle from byte buffer
	unsigned long packAxis = *((unsigned long*)fiveBytes);
	packAxis &= 0x00FFFFFF; // only uses low 24 bits
	fiveBytes += 3;
	unsigned long packAngle = *((unsigned short*)fiveBytes);

	// unpack axis and angle
	VECTOR3 axis = UnpackAxis(packAxis);
	float angle = ((float)packAngle)*PI/32768.f;

	// generate result quaternion from axis and angle
	float s = (float)sin(angle*0.5f);
	QUAT result;
	result.v.x = axis.x * s;
	result.v.y = axis.y * s;
	result.v.z = axis.z * s;
	result.s = (float)cos(angle*0.5f);
	return result;
}

Hope that helps!

- Chris

[AlCapowned]

Even though I'm not the one who's working on the plugin, thank you for posting that information. It would be great if VendorX finishes this!

[VendorX]

I was about to close this project, but with new info maybe i can finally finish this project. Anyway, i'm surprised that still someone is interested - this is very old game and almost all models are already in the net.

@chargrove: I know almost everything about .gem file format - only Ragdoll part left to do - but year ago I've stopped working on this project. Those 5 bites was too much... Now thanks to you maybe there is still hope.
...and thank you for help.

[GreatEmerald]

There are still a lot of weapon models that have never been exported. Your work is highly appreciated!

[Wail of Suicide]

Great news. I know I'd love to see some of those great looking Unreal 2 models elsewhere.

[AlCapowned]

Could you upload the script somewhere else, VendorX? The link in the first post is broken.

[VendorX]

Blender is changing too fast/too much, I will no longer update this plugin. Sorry...
CSharp version of this exporter is almost finished (still I have some problem with animation...) - just wait a little...

[VendorX]

Small update for those who waiting for release of new GemExporter:
Aidawalklookfrwd - test animation.

[AlCapowned]

That's awesome! Thanks again for all of your hard work.