Trying to get a conveyorbelt rig happening for a robot

Hi all, I guess this is honestly more of a Maya question though it does carry implications for importing into UDK in the long run.
Edited to explain technical problems more specifically. Also general STalker thread.



So this cute little guy is the STalker, and as you can see, he has some parts that don’t look very nice to come into contact with, which brings me to the current challenge and one that’s been stopping me dead. It’s the good old Bike Chain / Tank Tread conundrum. I’ve tried doing it manually and I’ve even been trying to get MEL scripts to work, but it goes as follows.


As you can see, I have a NURBS circle contained in a deformer mesh that gives it the shape I want.

The teeth will eventually number 25 and be spaced .04 apart from each other in terms of the 0 - 1 NURBS path. The problem is that whenever one of these teeth goes below the bottom half of the circle, it flips the orientation of of the tooth 180* in a direction I don’t want it to.

Arrrrrrrgh!!! Is there no way around this.

I think it might have something to do with where Maya is putting this thing on the curve but there’s got to be some workaround. Basically once it hits a certain point in this NURBS loop, it ruins an effect I have planned out adequate space for.

For the sake of troubleshooting, I have tried the following:

  • Deleted everything’s history and frozen everything’s transformations.
  • Played in depth with the “World Up” settings under Motion Path, but I’m still barely sure what this even does.
  • Deleting the NURBS and cage entirely and starting again from scratch.

First, I need to get this work. I’m studying that but if anyone’s ever rigged a bike chain or a chainsaw or something I’d love to know how you did it.
Secondly, I need to know how to bake this chainsaw motion in a way that I can import said chainsaw conveyorbelt directly into UDK as something animatable. Would I be exporting predefined animations? Would a NURBS loop UValue of 0 - 1 “blendshape” be a good approach? It would be nice if I had some control inside UDK to change the speed and direction of the conveyorbelt in code independently of the rest of the head. Is that possible? If so, how?

Thanks as always for your time.

~ Paige

I’m about to texture and rig this. It will be my first time doing either of those things (at least since I made silly FPS textures in high school, but that was ages ago) so any tips that will help me get this right for UDK are greatly appreciated.

STalker has ball and socket joints connected to his pelvis/jaw and a hinge joint for the knee attached to that. Hinged to a slightly velociraptor-inspired foot with two poseable toes. So it moves like a robot but has just enough personality combined with its retractable teeth and hinged, laughing head to get across some character, hopefully.

Any tips for this? Also his chainsaw/conveyorbelt mouth has still been a bit of a hard stop for me.

Thanks, guys, I appreciate it.

I went through this about a year ago when designing a rig for a little robot with tank treads used in an animated short. I had the exact same issues involving the inverted tank treads at certain locations… and oddly, no amount of intelligent scripting seemed to solve it. What i ended up doing was placing a locator in the center of the loop and telling the treads to always face towards it. This tactic was inspired by a very helpful tutorial on DigitalTutors called “Rigging Tank Treads in Maya”. I’d definitely check it out if you haven’t.