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ljilekor
08-09-2005, 04:10 PM
I have a flying bird to rig. Been a while since I used Messiah. In order to obtain some nice movement I used hold springs to simulate the latency of the feathers. Each feather is deformed by a bonechain. Those bonechains are made of holdsprings (all axis locked except Pitch) and are parented to the main WingBones. (See attachment)

First I tested everything with a testwing (since the def model was still in progress)

I did some testing, finetuning values. Great, I obtained a more than satisfying, versatile result. Nice movement.

Settings:

MotionDynamics :
Fluid density :1.0
Damping :1.0
Global weight :1.0
Pressure :0.0
GravityScale :0.0
StretchCorrections:10
Time sub-samples:2
Pre-IK


Springs
Each featherbone is a holdspring. All springs have the same settings :
All axis are locked, except Pitch.

MaxHoldRadius : 2.0
Strength : 4.0
Weight : 0.4
Damping : 1.0

Ok, I started rigging the def bird with full confidence. The def wing is approximatly the same size as the testwing. Bones are different but distributed appoximatly the same way. Same setup/same settings.

TOTALY DIFFERENT RESULTS. I can't even get close to the results I got with the test wing

The main problem is that (per feather) it's only the 1st bones in the chains that are influenced. The rest of the bones in the chains stay straight or (with other settings) wiggle allover the place. No way to get a smooth realistic simulation.

What's the problem with the damn hold springs ???
JoeCosman
08-09-2005, 05:20 PM
hold springs, when set to rotate only, do not propogate down the line. draw an imaginary spring from your default position to the current positin, and that is how the springs react:
a suspension bridge.

try adjusting the spring strength, going from strongest to weakest out to the tips of the feathers. (spring strength controls how much it will pull back. weak springs let it fall more.

also, set both stretch corrections and time subsamples to 5.

once you get a good drape, then drop the gravity scale, then the weight.

-JoeC
ljilekor
08-11-2005, 04:35 PM
Thx Joe.

I didn't try it 'cause my rig had to be ready the day I posted this.

Good to know 'bout that limitation.
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