CGTalk - Piston Coniption

jFive

04-22-2004, 03:16 PM

Hi,

I am reletively new to these forums and i am not sure if this is the right place to post this question. But here goes. I am mostly experienced with organic poly modeling and, well to be honest fairly basic character rigging. I can do skeletons, weights, Blend shapes etc. But, I have almost no experience with dynamics and many of the other advanced features maya offers.

Ok here is the question:

I am competing in the machineflesh challenge. My character design feature several pnuematic (I know I didnt spell that right) pistons and gears that drive the various cyber appendages of my character. I have no idea how to set these elements up so that they will be mobile with out me having to keyframe everything.

I know that I will need to use expression driven animation for the gears. But even in the new book i just got I am not finding anything that I can directly relate to setting up a sliding joint for a piston.

Frankly, I'm lost and the guru who I would normally consult a Mr. Ian Eisenberg no longer teaches at AIFL where I graduated from last year.(you reading this Ian?) So he is unavailable to ask these technical questions.

If you have any ideas or suggestion please share them.

thank you
J5 Out
:bowdown:

Borkowski

04-22-2004, 09:31 PM

Hey, I've done something similer to what you want with some mechanical wings. I used maya 5.0, here's the process:

make two locators and place them where the piston attaches to the robot at either end. Then use an aim constraint on one of the locators so that is is always pointing towards the other one.
Parent the piston object to the constrained locator.

Now pose your character in an extreme pose where the piston will be fully closed... it should be at the right angle just too long. So make a blend shape for the fully closed pistion.

Now you just need to make a set driven key; where the bending of the robots joints drives the blend shape and thus closes the piston as the joint bends.

One thing that may work that I havn't tried binding the piston to a two joint skeleton that is scaled along it's axis istead of a blend shape, this would give less control over the shape but should work even your piston is not a seperate object.

I hope that makes sense.

good luck.

jFive

04-23-2004, 03:09 AM

That sounds like a good idea i will try that and see if i can make it work. But for now back to modeling

j5 Out
:bounce:

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