I would like to begin covering bone dynamics. What this feature does is modify a chain of bones to behave according to movement and forces. Most examples that are given are pony-tails or just regular tails. However it can be used for so much more. This tutorial will just demonstrate how to set up a basic bone simulation system. I have plans for a more detailed example later where the aim is to achieve a particular effect. When used correctly, dynamic constraints can achieve the effective look of soft body dynamics such as Joe William's "Hunter" model.

Here we go!
Let's start out by creating a cylinder with 4 sections.
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Switch over to Bones mode, and add 4 bones. Start from the bottom, click "a" and drag a bone from the base to the 2nd ring. Click "a" again to add the next bone. Make sure that click the endpoint of the previous bone, otherwise you will have a broken bone chain. When all four bones are in place, make sure you rotate all the roll handles in the same direction. This is a good habit to keep in order to have nicely behaved dynamics and animations. Now associate the CPs with each bone as in the picture. You should have something that closely resembles this.
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The next step can be done as an action or it can be done in the choreography. I'll perform it as an action in this example.
In the project workspace, right click on the Action folder and add new action. If your cylinder is the only object in your project, then it will be auto selected, if not, please click on your model name.

When your model shows up in the action window, it will show all the bones inside of your model. Right click the top most bone, (Bone 4) and Add New Constraint, use Dynamic Constraint.
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Make sure that in your Tools->Options Menu, Global Tab. That you have advanced properties Checked and Show Property Triangle Checked.
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Now expand your properties for the Dynamic constraint applied to Bone 4 like this. Open up Dynamic Options and Targeting.
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All of the options underneath that Constrain are described in the AM Technical Reference AM Technical Reference: PDF The Dynamic Constraint section is only a few of pages and is well worth the read. In this Tutorial I will mostly be covering the Options that are associated with forces.

Currently, the Dynamic Constraint Enforcement is set to 100%. This tells the last bone in the chain to have 100% of the effect of the dynamic simulation applied to it. The Stiffness option under Dynamic Constraint-> Dynamic Options -> Targeting ->Stiffness is what defines how limp or stiff the chain will behave. Leave the stiffness at 50%.

Create a new Choreography. Drag your cylinder model into the choreography and rotate it 90 degrees clockwise from the Z axis (Looking at it from the front). You should have something like this.
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Now drag your action that you created onto your model.
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In order to give the simulation time to react, set your Choreography length to at least 6 seconds.
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***Reminder*** If you haven't saved yet, this would be a good place to do so.

Now right-click from within the choreography window and select Simulate Spring System.
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Watch the Magic Happen! Well, it may not be super exciting, but what you are seeing is the model deforming according to gravity and recovering into a rested state where the gravity, and the dynamic bone are in equilibrium.

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By Tweaking the Enforcement of the Dynamic Constraint, it will change the behavior of the simulation. Small Enforcement values will end up acting like a limp rope. Higher enforcements will act like a flagpole mast. Both are subject to the Forces objects as well. I will demonstrate here.

By adding a new force of Box Shape and Fan Type. Set the Magnitude to something like 1000%
Drag the Force into the Choreography and aim it at the tip of the model. Something like this.
Adjust the Stiffness value under the Dynamic Oprions->Targeting to 5%
Refer to the next figure to see if your settings match .
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Simulate the new Choreography and render it out. It should behave like this.
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If a picture is worth a thousand words, this is worth a thousand pictures. You are very good at this 'splainin thing. Thanks

Are you sure about this part...



this seems counter to everything I've seen. 100% should mean the bone will behave exactly like the constraint dictates and 0% should mean mean the bone will not be influenced by the constraint at all. That is how all other constraint enforcements work.

Dynamic enforcement just turns the constraint ON/OFF. 1% to 100%=ON and 0%=OFF, even if the enforcement interpolation is set to linear, so 25%=100% enforcement. The dynamic enforcement does not work like regular constraint enforcements.

Are you using v15? Does changing the enforcement work in v15?

Good Catch! I didn't even realize it! I'll go ahead and correct the article.