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DIY Jiggle Deformer:

download jiggle.mb here

This is a simple jiggle deformer setup that I learned from someone who worked at ILM.  They came to Texas A&M and taught part of a summer course.  It was a great experience.  This was useful back before Maya had a jiggle deformer.  It may still be useful in certain situations.  I used this setup for the leaves on the vines in this sequence of Avatar:


The basic idea is to use an IK Spline system where the spline curve is goaled to a soft body duplicate of itself.  This becomes a simulation, so you can't scrub, but it's simulating one particle per joint so it doesn't really effect playback speed.


Step 1: Joints
Set up a simple test cylinder with a sphere perched on it.  Create a joint chain.  I created the joints in the side view with snap-to-grid and snap-to-view-planes turned on.

initial setup

Step 2: Curve

Next, create a NURBS curve.  Again in the front view, from the create dropdown choose create--> curve tools --> cv curve tool.  Then just click on each joint to create the NURBS curve CVs.  Hit enter when you're done to end the process.

Step 3: Soft Body

With the curve selected, create the soft body.  Note that Maya has two particle systems, the old "Legacy Particles" and the new fancy nParticles.  In this case we can use the old particles.  Switch to the FX menu set.  At the bottom of the nParticles drop-down there is the soft body tool. 

Open the options box for the soft body tool and choose "Duplicate, make copy soft".

Tick the box that says "Make non-soft a goal".  Change the weight value to 1.0.  Hit Apply.

soft body

Now, take a look at the child nodes of copyOfCurve1.  In addition to the usual copyOfCurveShape1 we also have copyOfCurve1Particle.  This is the particle system that will drive the soft body that will drive the spline IK that will jiggle our geometry.  So, we still have to set up the spline IK and then adjust the goal weights per particle.

Step 4:  Spline IK

Creating the spline IK handle is a bit of a chore.  First, hide the cylinder and sphere geometry.  Also hide curve1.  When we create the spline IK we will have to select the driving curve in the viewport.  Having the two curves sitting on top of each other will make our job very difficult.

Switch to the Rigging menu set. 

Choose Skeleton --> Create IK Spline Handle, and open the options for that tool.  Turn off "Auto create curve".  We already have a curve we want to use.

Choose Skeleton--> Create IK Spline Handle again, without the tool options this time.  Follow the instructions in the lower left part of the Maya main window. 
        Select the root joint
        Select the end joint

        Select the copyOfCurve1 curve

As soon as you select the curve Maya should create the spline IK handle, called ikHandle1.  You can select that handle, but you can't move it.  It is a spline IK handle, meaning it is being driven by a spline curve - copyOfCurve1 in our case.  We need some animation to test the follow-through jiggle. 

Set a keyframe on the transforms of curve1.  Go froward a few frames.  Move curve1, the curve without the particles attached, a few units away from the origin.  Rewind and hit play.  The soft body curve and the joints should follow along with some bouncing behavior.  The particles are trying to reach their goals.

Step 5: Goal weights

Now we need to adjust the goal weights for each particle, so that one end is floppy and the other end is locked to the joint system.  

Select the particle shape node and open the Goal Weights and Objects section of the Attribute Editor.  Since we checked off the "Make non-soft a goal" we should see a slider labeled "curveShape1" set to 1.0 as we specified earlier.  Just double check that setting.  You can also play with goal smoothness.  This is one of those abstract Maya settings.  It is basically a scale on how quickly or slowly the particles reach their goals.  For the gif above I left the Goal Smoothness at 3.0.

Now we need to adjust the individual goal weights for the particles, so we need to select them in component mode.  This may or may not be a pain in the ass.  One way to select the particles is to go to the "Show" drop-down at the top edge of the perspective view and click Show-->None.  Then open the Show drop-down again and click Show-->Dynamics.  Select the particles with the mouse.  Now right-click in the perspective view and choose Particles.  Now swipe over all the particles to select them.  You should see copyOfCurve1Particle.pt[0:6] in the very top frame of the main Maya window, towards the right.

Open windows --> General Editors --> Component Editor.  Click on the Particles tab.  You should  see goalPP in the far right column.

Change the goalPP values so that they range between 0.5  and 1.  You want 0.5 at the jiggly end, and 1.0 at the rigid end.  Rewind and play again.  Adjust to your liking.  That's the whole setup.  You could drive curve1 with another joint system that you could expose to animators, and then hide or lock the curves, joints and spline IK handle.