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June 13, 2021
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8 Tips For Animating Active Ragdolls

by Lorcan Mc Garry Hunt on 05/28/21 11:57:00 am   Featured Blogs

The following blog post, unless otherwise noted, was written by a member of Gamasutra’s community.
The thoughts and opinions expressed are those of the writer and not Gamasutra or its parent company.

 

Got asked for some tips about how I animate my Active Ragdolls so here's a list of some of the techniques that I have learnt over the last few months to help save everyone some time.
 

Basic Animation - You can get some pretty good results with just basic force impulses and hovers. Most of my ragdolls' walk cycles are done by just telling the foot furthest from the target direction to jolt forward and up a bit, and then have the other do the same when both are grounded again.
A Satisfyingly Punch - Making a fist jolt forward to punch will work, but come of as a bit lacklustre if the rest of the body is unaffected. To get the most out of your ragdoll animation, try increasing the weight of the moving body part for a few frames as the force is applied. 
This increase gives the moving part more influence over the ragdoll and makes the entire body follow the motion, with little work on your part.​


See it lean into the punch, because the fist weight is increased for a few frames so it 'pulls' the body behind it.

Drag & Weight - When setting up your ragdoll it is important to get the drag and weight of different body parts right. High drag will leave you with a character that's too stiff, and too little will make one that moves too much like a doll.

I recommend making a manager script that you can use in game and editor that lets you set a total weight and drag for all parts of your ragdoll to add up too, and then have it work out what fraction of the total value each part uses. Doing this lets you quickly change and test out different settings as you refine the overall character to find the prefect balance.

Gravity - Making a custom script to apply gravity, rather than the rigidbody components default, is a must. Something that lets you change the center of mass, and strength, gives you more control over the body's default pose.

No Vertical Drag - Drag is very useful to help make your ragdolls less doll-like, but too much and they will look like they're swimming in honey whenever they are falling. Make a custom script that lets you separate vertical drag from horizonal.

Check The Fall Speed! - Use the manager mentioned above, and remember to check, after major changes, that your character's fall and horizonal movement speeds still feel right.  Compare it against other objects!

String Puppet Design - I talk about this design in my main video about Active Ragdolls, but when starting out with active ragdolls, you may find it easier to take out connecting parts of the limbs, and only have a physical torso and limb ends (hands & feet) with purely visual IK driven arms and legs to join them.

 My first Active ragdoll, simple design, fast to animate

While they may be a bit less physical, they are easy to set up with simple spring joints, and make for fast ragdolls to test and animate for beginners.

Inverse Kinematics - Force Impulses will work for most cases, but If you want more complex animation, techniques from procedural animation and inverse kinematics can work pretty well when applied to active ragdolls.

My moderately complex Active Ragdoll from my current game, uses IK and typical procedural animation for its more complex body balancing and stepping motions.
 

That's it for now! I plan to cover all this, and more, in greater depth with a series of 1 minute videos in the future, but thought it would be good to do this basic text post in the meanwhile.

And to see my released and in progress games that use active ragdolls;
Gaggle Brains (Full Release) - https://store.steampowered.com/app/1542870/Gaggle_Brains/
Days With Dino (Alpha Demo) - https://birdmaskstudio.itch.io/days-with-dino
More Active Ragdoll updates here - https://twitter.com/BirdmaskStudio

Want to know more about active ragdolls? You can see my full comprehensive video about what they are and how they work here.


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