CGTalk - Question: XPresso

VagabondDead

08-22-2004, 12:08 PM

I've decided to explore animating a little bit before I practice more modeling and texturing (I get bored quickly), and I'm trying to write an xpresso tag to keep a robot's foot always pointing down. Basically, I calculate the rotations of the two leg-parts above the foot, add them together and negate the value to give the foot it's B-rotation. The problem is that it seems to warp a little bit, or at least not quite work. I've checked to see if something else could be rotating and affecting the hierarchy, but it goes: anchor-upper-lower-foot. Any help is appreciated.

I've included a scrnshot of the expression and a picture to show what I'm talking about.

http://homepage.mac.com/joshbear/xpresso1.jpg
http://homepage.mac.com/joshbear/xpresso2.jpg

Cheers,
Josh

nendo_3d

08-22-2004, 12:18 PM

pictures aint showing. try making them jpeg instead of pdf have u got a a bone system set up or are u using the mesh?

VagabondDead

08-22-2004, 02:27 PM

Oh yeah, forgot that OS X defaults its screenshots to .pdf.

Should be fixed now.

Cheers,
Josh

VagabondDead

08-23-2004, 04:03 AM

Sorry to bump my own thread; if it scrolls off again I'll let it die. I'm just still hoping someone can help me.

If you need more information, let me know. If it's a really stupid mistake, plz let me know. If it's a RTFM, plz understand that my manuals are in a different country. I read through the xpresso section in the .pdf, but I can't just browse a pdf so if it isn't in the obvious section, I won't find it.

Nendo-3d: no bone system or deformers. Just using separate objects in a hierarchy.

jono338

08-23-2004, 05:04 AM

Easier to just pipe a constant 0 into Global Rotation.P

VagabondDead

08-23-2004, 06:32 AM

Ah yes. The reason I wanted to do it as a local coordinate is because I wanted to clamp the value between -90 and 90 (the maximum angle the foot should ever turn). However, for the time being using the global.b works. Thanks. However, I still have the deformation.

Here's 2 pics showing it. The only difference is that I changed the position of the IK target for the 'upper' leg.

http://homepage.mac.com/joshbear/pic_3.jpg
http://homepage.mac.com/joshbear/pic_4.jpg

As I said, I don't have any deformers in my scene at all. Only IK tags and now s imple expresso statement that says constant(0)->global.b for the foot.

Any reason it would deform?

Thanks,
Josh

mart1jn

08-23-2004, 10:48 AM

Hi Josh,

It looks like a model vs object tool issue. You probably used the object tool while modeling.
The manual explains it better than I can do here, so look at p. 405

cheers
Martijn

VagabondDead

08-23-2004, 12:59 PM

Thanks for the reply Mart1jn!

It turns out I adjusted the scale of the object axis at some point (by accident), so the x, y, and z values were different scales.

It's working now.

Thanks,
Josh

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