A fluid blend from kinematic into ragdoll

Excellent question, here’s a few tips and tricks to get you started.

Final Result

Let’s have a look at what we’ll be creating.

The ingredients are as follows.

  • Animation from Kinematic to Dynamic, for the overall effect
  • Normal Rotate Stiffness on the rGroup node, for blending out and into a pose
  • Pin Constraint to blend the hip out and into position

Here is a step-by-step.

1. Setup

Use your own character and animation, or grab the Manikin rig along with some motion capture from here.

2. Animate Kinematic & Dynamic

For the overall effect, I’ll first transition out of Kinematic into Dynamic.

3. Solver Start Frame

Because I’m not simulating the first 40 frames, I’ll set my solver to start simulating on frame 40. That way, I won’t have to play from frame 1 so often.

4. Group Rotate Stiffness

Next I’ll stiffen up the character, such that when he becomes Dynamic he’ll remain in the mostly-animated pose. Something we can then slowly transition out of.

5. Pin Constraint

To keep him from falling over, I’ll add a Pin Constraint to his hip, spine and head. Exactly where and how many of these you make will vary and is depends on taste.

6. Animate Rotate Stiffness

Now I’ll slowly transition out of the pose by animating the group Rotate Stiffness attribute.

7. Animate Pin Constraints

Likewise to slowly let go of the hip, I’ll animate the Pin Constraints too.

Conclusion

And there you have it! A few things to look out for is your animation going outside the limits of your character at the time of switching between Kinematic and Dynamic. If your animation e.g. breaks the elbow limit, then it’ll snap back into that limit as soon as it becomes Dynamic. You can either adjust your animation (for most realistic results) or the limits to work around that.

You’ll also want to tune the Damping values; a low Damping means a closer match to your animation, at the expense of a very springy-looking motion. I found that during the transition it can help to increase Damping to help smooth it out.

Hope it helps, good luck!

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