How to apply bounce to 'breast bones' in female model

Hello all,

I’m a fairly new Blender user, and I’m totally new to animating in Blender so I’m a bit lost on this-- I have a fully rigged female model I’m looking to use in a video game and I’d like to add some jiggle to her breasts. She has ‘breast bones’, but at the moment everything is static. What’s the best way to approach this? Can anyone point me to some good tutorials on SB/armature integration that would be relevant to this end? Also, are there any plugins or scripts that help in the creation of ‘jiggle physics’ in Blender? Seems inevitable that someone would create something like that eventually :slight_smile:


Well, on my experience, bones probably won’t do quite what you want them to in this case. SoftBody is better suited for that. You need to adjust the physics quite a bit to get good motion (plenty of friction, mainly). And when you set the VGroup for the Goal, make you set it to include all vertices except for the breasts. This lets it know where to apply softness.

You can use this for other “soft” body areas as well, depending on how much body mass you’re dealing with.

I think Belphegor’s answer is probably the best, but there is a way to do it with Bones. Just make the breast Bone a segmented B-bone and place a non-deform bone in front of it. Then make an IK-chain from that new bone to the breast bone. If you now move around the non-deformer you can add a bit of jiggle.

Another solution would be to use Lattice modifiers.

I actually did this on a test makehuman imported model. Just to see if it would be possible. What I did is use the same armature that I rigged the character with. then I made two bone in the armature. One for each breast,but not connected to any other bones Then I used a copy rotation for left breast bone to the right thigh and weight painted just the breast to that left breast bone. You have to adjust the influence of the constraint to your liking, you not want that it to copy the full rotation of the thiigh. I did the same thing to the right breast bone. Then whenever the character walked her breast would jiggle. As I said you have to adjust the influnce of the contraint to your liking.

This type of rig made an “opposite” breast bounce. That is right leg foreward----> left breast bounced up, Left leg forward—> right breast bounced up. You could make the constraints on both breast bones copy just one thigh bone if you want the breast to move together. I just did it my way to test itout as I said. What you do have to be careful of is when each thigh bone is trailing behind the torso. You have to adjust the constraint to NOT collapse the vertexs of the mesh when that happens. I know I had a way to do it but I cannot remember right now how I did it and I am away from my home computer so I cannot pull up the blend file.

As I said this method worked for me and it was just a test that I did to see if I could do it. Your results may vary

what’s the engine? Doom 3 engines have this built in. You set it up in the AE editor.

EDIT: you’d still need bones bound to the breasts for it to work.

I would assume he is talking about animating this in blender since he is asking on a blender forum. Or at least he is talking about putting it into the blender game engine.

She might end up in multiple venues actually-- I use Darkbasic Professional and its derivative FPS Creator (yes, I know the FPSC requires a specific biped rig that comes easiest from 3ds Max and will therefore entail further tweaking even if I get this going in Blender) but I am planning on using the Shiva 3d Engine and SIO2 engine in the near future for multiplatform/iPhone development. Whatever the case, I’m interested in breaking into the realm of CG art anyhow so even if she never gets used as a character I’ll be happy I got her looking good! I’m still just getting started and the promise of some custom breast physics to admire is the carrot at the end of the stick leading me up what can be a rather steep learning curve. (and before you say this is too complicated a task for a noob and I should set my sights on simpler tutorials-- I am spending the majority of my Blender study time with intro tutorials; this is just a fun side thing I wanted to try out since the model was pre-made basically for the purpose of testing things out).

Thanks for the replies! It may take me awhile to figure out exactly how to implement your suggestions in the Blender interface, but it all sounds good.

If I can find it I will post the blend of the figure I did. As I said it was just a test and it was a few years ago so I will have to look thru several files

Well I found it but cannot find a way to attach a .blend or .avi here in the forum

Ok I found how to upload it but it exceeds the file size limit.
I will find some file space online and keep you updated.

never make any assumptions. :slight_smile: He never specified blender except as the modeling & rigging app.

Just check to see what the engine supports. If it’s all vertex animations then you’d use the soft body method. If it supports jiggle bones then you could rig it & setup the boobs however the engine says to set up jiggle stuff. If it’s bones & no jigglies (which I’m betting it is) then you’d need to animate it yourself.

There was a bear falling .blend someone made as a tutorial for making a ragdoll in blender. That’s what you’d want for “real” jigglie boobs: a ragdoll.

But, in reality, unless she’s got large real boobs (vs the silicone ones)she won’t jiggle anyway, especially in a bra/tight clothing.

@Friar: Hehe, yeah but we aren’t talking about reality are we? :wink: Any chance you remember where I could find that ragdoll tutorial you mentioned? I’ll search, but a link would be awesome. What exactly did you mean by “If it’s bones & no jigglies (which I’m betting it is) then you’d need to animate it yourself.”-- if I animated it in Blender could I still use it in any given engine? Also, just a general question about the relationship between 3d material creation apps and game engines-- besides what you mentioned specifically above (thanks by the way) what CG support qualities should I look for if I want to achieve animated physical effects like the jiggle in question? What properties [if anything special] might an engine require to properly reflect the effects of Shaba1’s experimental bone method mentioned above? Regarding Blender specifically, if I go the soft body route will any given game engine just ‘know’ how to treat the model or does the engine have to specially support soft body physics? I’m just transitioning from 2D to 3D and it’s a little confusing at times trying to figure out how the various applications/engines communicate…

@Shaba1: Thanks a lot for your continued efforts! It sounds like your .blend would be very helpful if you can find a way to get it on the net.

Adding to Happy Friar’s good words:

In the past gen Unreal engine, there were 2 ways to do character/object animation that showed mesh deformations – with a skeletal rig, or with vertex animation (aka morph targets, shape keys, relative vertex keys, etc.). Obviously the skeletal method uses bones, and this is the more efficient way for game characters, so many engine support this very well. But usually it’s ONLY bones – the only thing that moves the mesh in-game is the movements of its skeleton (armature). So for boob-bounce you’d need to keyframe in the jiggle, unless (as some have suggested) there is a special routine in the engine to do that, based on bone naming. This is similar to how weapon attachments are done – special coding for a specially-named bone. But you’re also at the mercy of whatever the game provides in terms of bounce magnitude and “realism” (which usually panders to young adolescent fantasies rather than physics and anatomy! :rolleyes:)

The other animation method (vertex keyframing) is the older of the two, but also more limited in what it can accomplish. With vertex animation all mesh shapes are predetermined and encoded in the object – basically just like a set of shape keys – and the engine lets you spec when and how long the animation(s) runs, whether it loops, etc. This is akin to Shape Actions in the BGE. To get boob-bounce using this approach, you’d have to set your model up with the breasts as soft-body objects, then export the resulting animation as Vertex Keyframe Animations (.mdd).

The problem here is whether your engine can combine these processes – most can’t afaik. If you use skeletal anims, you need to do bony breasts, which means hand-keying the bounce or using the engine’s code. If you want to do vertex animated breasts, then your character animations will also have to be vertex anims, which is extremely inefficient, and not many engines support this as completely as they do skeletal animations because of the limitations.

This may have changed in more recent commercial game engines, but investigate the freebies carefully to identify the possibilities and limitations.

Thanks chipmasque, that clears things up a good bit. What exactly should I look for in the descriptions of the engines to discern what effects they might be able to handle (specifically if they would support breast physics well :wink: )? For example on the site, many 3D game engines are broken down by features with buzz words as follows:
[For the ShiVa 3D engine, which I own and am planning to use]

Physics: Basic Physics, Collision Detection, Rigid Body, Vehicle Physics:
Animation: Forward Kinematics, Keyframe Animation, Skeletal Animation, Animation Blending: Meshes: Mesh Loading, Skinning:
Surfaces & Curves: Splines:
Some of that makes sense to me, but just as an example to illustrate my confusion- would ShiVa ‘recognize’ any soft body physics applied to my model despite the fact that it doesn’t specifically mention soft body physics in its feature list?

Given that list, it’s unlikely that soft body physics would be supported directly, particularly Blender’s “flavor” of that effect. Not all physics is coded the same from engine to engine, hence the variety of physics solutions that can be found in commercial games.

So the trick is to learn what the engine can do, then tailor your needs to those capabilities/limitations. For example, in the game Unreal II there was a female character with a rather generous chest. She bounced a lot in the game, rather unconvincingly and comically imo. Given that at the time Unreal characters were animated using skeletal rigs (usually a variation on Biped), it’s more than likely that her breast bounce was bone-based, and made a part of her character animation cycles either via keyframe animation or special coding.

About Shiva’s list:

Physics: Basic Physics, Collision Detection, Rigid Body, Vehicle Physics: no mention of soft-body, so I’d say it’s not in the cards. Some game effects I’ve seen resemble soft-body reactions (hair, clothing and accessories that have cloth-like motion in-game, etc.) but whether or not this is true soft-body or some feature of a physics package the game uses I can’t say. Basic physics usually refers to things like Gravity – truly basic. Collision Detection is so player models can interact with stuff, Rigid body governs the boxes and barrels, things that hang from hinges and chains and what-not, and Vehicle is self-explanatory. But keep in mind that all these “physics” are just code, and that code may or may not conform to any particular implementation of game physics. Good way to find out is build a little test level and try things out.

Animation: Forward Kinematics, Keyframe Animation, Skeletal Animation, Animation Blending: This sounds like standard fare. Not sure why FK would be specifically mentioned unless the game itself has some basic animation capabilities, for stuff like mechanicals and the like. AFAIK modern Unreal characters use both IK and FK in their native animations packages (usually Max or Maya), but when the models and rigs are imported into the game, they are translated into a proprietary native game format for skeletal anims. It could mean that Shiva does NOT support IK-driven rigs. Much as I like FK for some uses, not being able to use IK for character models may be a serious limitation.

I assume that “Keyframe animation” means Vertex Animation, the shape key/morph target approach. While rarely used for character anims nowadays, it’s still popular for some kinds of animation, especially loops like flags in the wind, pulsating forms, anything where the animated mesh changes its overall shape/volume substantially. Anim blending is exclusively between skeletal animation sequences afaik, making for smooth transitions between various animation cycles.

Meshes: Mesh Loading, Skinning: I’m pretty sure “skinning” here refers to applying various texture packages to the same model to provide variety of appearance.

Surfaces & Curves: Splines: I’m unclear what this capability describes, other than that the engine supports some geometry types other than polygon meshes.

Doesn’t look like breast-bounce is directly supported, other than being incorporated into skeletal animation cycles. In Unreal games, bone-based “auto-bounce” could likely be coded in even by a modder, since all the Unreal Script classes are exposed and easily sub-classed. Look into Shiva’s scripting options, you could maybe write your own booby code?

found the ragdoll .blend file. ends up it was on my desktop!

Remove the .blend, it’s actually a .zip file.

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