View Full Version : help on a bird rig

10 October 2002, 02:37 AM
ok here it goes. I've been trying write an expression based on the rotation of a main joint. the problem is that I want the affected joints to react one way such as when the main joint rotates from 60 to -60 the effected joint to rotate down and then switch to an oppisite rotation when it rotates from -60 to 60. Think feathers on a bird, when the wings rotate down the feathers encounter resistance And the opposite on the way up. I figured out how to do it based on time but that kind of limits what you can do with the rig. Any help would be great.

10 October 2002, 05:50 AM
Hey Spyder,

I'm not sure if this is what you're looking for, but I think this might work for ya.

I made 3 joints in a chain:

Then I made an if/else expression that controls the Z rotation of birdjoint2 based off of the Z rotation of birdjoint1:

if (birdjoint1.rotateZ>0)birdjoint2.rotateZ=birdjoint1.rotateZ *2;
else birdjoint2.rotateZ=birdjoint1.rotateZ/2;

The attached image are the results...

I hope this helps! :thumbsup:



10 October 2002, 05:58 PM
also, i think u can use set driven key. u can control the way of move in graph editor.

10 October 2002, 07:08 PM
Ok let me try to explain this a little better. What i'm having a problem with is when the feathers rotate down (image A ) i have an expression that has them lag behind a bit. The problem that i encounter is when they reach the end of the flap (on the way down ) and start to rotate up it just does the same expression in reverse. What i would like to have them do is when it reaches the bottem of the flap i would like the feathers to revese their direction and look like they are encountering resitance. Image B shows what i want it to do when on the way up. Some people that i have talked to said that i might need to use a hermite curve to do what i am looking for...Thanks for all the help so far and i hope this clears it up a little.

10 October 2002, 07:09 PM
here is image B

10 October 2002, 09:33 PM
So throw a math function in there to slow it down. Divide the rotation by a # on the way down and that should solve your problem...I think you're looking too much into this, this is a very easy thing to accomplish. Don't overdo it.



CGTalk Moderation
01 January 2006, 08:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.