View Full Version : Setting up hydraulics

08 August 2007, 11:29 AM
hi! i am not very good at character work, but im building a nice model and want to rig it for my friend to animate. So i set out building a crazy daemonic killer robot of doom. I can set up most of the hydraulic constraints, but the ones going at odd angles are throwing me off. I want to set up the hydraulics so it looks like they are driving the legs and what not. most of the tutorials just have the hydraulics going off at nice right angles, mine unfortunatly do not.
here is a screen grab of my scene...
warning its a big image 2560x1600.

i tried using straight bones, straingt aim constraints and a combonaton of bones and aim, i got pretty ok results, but sometimes the rigs totaly fail, other just dont work.

the next will be how to set up self animating tubes and shock absorbers, but i will burn that bridge when i come to it.

08 August 2007, 05:56 PM
I made this tutorial video on rigging a piston that may be a helpful starting point:


08 August 2007, 06:34 PM
hi, have u tried using the set driven key nodes (i mean its indirectly an animation node ) ? set driven key is a really useful node(obj) type in rigging ... ! i mean you can sdk a part of the setup along with those constrains - the goal here is to have a slider (or) a attribute (or) a movable controller when used should animate those pistons, am i getting it right ?

09 September 2007, 02:31 PM
John, thanks for posting that video man, i'm checkin out your website right now :D

09 September 2007, 07:40 PM
i would not rig the geometry directly. NEVER ever rig geometry directly! especially for real productions where geometry might be revised at any time... you dont want to lose your rigging (and possibly animation data) if you have to change the geo.

you were on the right track by using joints but instead of lousy bugged dont work aim contstraints, just use the IK. ik is one thing you can rely on in maya. heres a quick example i made in less than 5 minutes.

the nurbs circles have the joints nearest to them parented to them, and the bottom nurb circle has the IK handle of the TOP joint parented to it also, the top nurb circle has the ik from the BOTTOM joint parented to it. this forces the joints to always point correctly no matter how you move the circles, no flipping to ever worry animate it by moving the nurb cicles, not directly touching your joints or geometry. the geometry is simply parented or bound to the joints, here i just parented it but really in a production rig i'd probably bind it to keep the heirarchy simpler.

to integrate this piston into a character rig, simply position an already rigged piston where you want it on your character, by moving the top and bottom control circles on the rig. then parent the circles to whatever joints you want to drive the piston. then it will work automatically, as you move or rotate the joints, the piston will do what u want. no need for set driven keys or anything complex.

also i you must turn off "snap enable" on your IK so that you can move the end effector off of the joint and all the way to the nurb circle it is parented to, so that the joints point correctly.

if this is confusing, just downoad the maya file and check it out:

09 September 2007, 09:42 PM
I agree with Yenvalmar, don't rig the geometry directly. ( I did that in my movie to try to keep things simple, but I'm setting a very bad example. Sorry!)

09 September 2007, 10:08 PM
hey! thanks for all of the replies, unfortunatly my power is out in half of my apartmet, the half with my computer. So i cant try them out :( If i cant rig them how i want, i figure i can change the geometry. I guess the best way to describe how i want to have the joints move is similar to how shock absorbers are mounted to a car.
Ill be sure to post my progress when i get my power back =D

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09 September 2007, 10:08 PM
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