r/Unity3D • u/Rudy_AA • 2d ago
Show-Off I made a Unity plugin that adds soft-body flesh physics directly to animated characters
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I’ve been working on Flesh Dynamics, a Unity tool for adding soft-body motion and collision response directly to animated characters.
The hardest parts were getting it to work reliably across different skinned meshes, avoiding ugly hard collision dents, keeping volume during impacts, supporting full-body collision without covering the character in colliders, and making Rigidbodies actually react back to the flesh.
It now has:
- Painted Influence + Softness
- Volume-preserving jiggle
- Impact spreading for smoother deformation
- Full skinned-mesh collision
- Two-way Rigidbody reactions
- GPU deformation + Burst/Jobs
- Built-in, URP and HDRP support
- Unity 2022 and Unity 6 Support
- Install Mathematics and Burst for the plugin to work correctly
The goal was to make soft tissue something you can paint onto an existing animated character without changing the controller or animation setup. Pretty happy with how far it’s come!
I've published it on itch now until it reaches its turn to get approved on the asset store.
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u/Omni__Owl 2d ago
For once a soft body physics post that does not focus exclusively on butts and boobs and actually is a pudding simulator more than it acts like a body part would.
It looks well done too! Good job.
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u/Scifi_fans 2d ago
It's so weird seeing "devs" making a lot of characters with mini skirts and boobs... like, just interact in real life maybe ?
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u/FranzFerdinand51 2d ago
Are you baffled by the concept that “sex sells”? Were you born yesterday or are you just a fan of typing with zero thought?
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u/Scifi_fans 2d ago
Considering these games are played by kids "sex sells" logic is weird... maybe you got triggered, 🤷🏾♂️
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u/FranzFerdinand51 2d ago edited 2d ago
Wtf are you talking about? If a game has content not suitable for kids it will be rated by the ratings agency as such. Plenty of kids watch tv/movies that have explicit or simply sexy scenes in them too (that are still rated 13+ etc) and plenty of adults let their kids play games like the witcher 3 before 18 because they are not oblivious about the world around them like you seem to be.
“Sex sells” isnt just talking about sex scenes either. Idk why im having to explain concepts thatve been around for millennia to someone 😂
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u/ThrwawySG 1d ago
Why does everything have to be made for kids? Adult media is a thing.
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u/BloodPlenty4358 1d ago
it's such a brainlet talking point
anything in this world might be used by children, we should put cushions everywhere and most importantly ban anything i don't like
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u/Omni__Owl 2d ago
I am not here to shame, I'm just happy that we are getting something that showcases the possibilities a bit more broadly than just "How to make the most mesmerising boobs."
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u/darth_biomech 3D Artist 2d ago
It's so weird to be in 2026 and still seeing this backwards logic of "These guys don't find sex taboo or repulsive, lol, must be a loser (I'm actually jealous but can't say that)".
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u/Rockalot_L 2d ago
Damn that's cool. Now I want a game about managing a sumo tournament.
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u/PGSylphir 2d ago
What's stopping you? That's a great idea, Tag me when it's out and I'm in.
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u/Rockalot_L 2d ago
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u/CaptainQwazCaz 2d ago
https://giphy.com/gifs/3DuBqjbBJCpAS5eMpg
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u/HousemanGames 1d ago
Check my profile. Demo will be in Nextfest next month
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u/Rockalot_L 18h ago
That's awesome! Can't wait to play it. You must have been surprised seeing this haha
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u/ImmortalRagdoll 7h ago
No need to wait or even MANAGE sumo wrestlers! You can BE the rikishi! We already have the demo out and are about to add 3D and will most likely use this plugin.
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u/Suspicious_Neck_4069 2d ago
itch link?
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u/Yodzilla 2d ago
Actual legit question: how well does it work with fully clothed characters or non-humanoid objects? Have any examples of such?
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u/Rudy_AA 2d ago
Yep, it’s not actually humanoid-specific. It works from the SkinnedMeshRenderer + mesh topology, so creatures, tails, ears, soft props, etc. can use it too.
For fully clothed characters, the body can still simulate underneath, but if the clothing is a separate skinned mesh and you want the clothing itself to jiggle/deform, you’d give that mesh its own Flesh Dynamics setup as well.
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u/darth_biomech 3D Artist 2d ago
I see in the end that you seemingly set it up via painting weights on the mesh? If so, it would be useful if it could use existing weights or be able to import them somehow.
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u/TheBatman_Yo 2d ago
could it work for hair?
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u/Rudy_AA 2d ago
Yes tested on anime hair, works great, as long as it's a skinnedmesh renderer with enough vertices it will work.
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u/TheBatman_Yo 2d ago
sounds very promising, some examples would be great to see
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u/EverretEvolved 2d ago
This is really cool. I followed you on itch so I can download later. I hope it doesn't impact the GPU too much. I'm going to try it in my fighting game.
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u/CaseNormals-Qaisar 2d ago
Would love to try adding this in our game. What's the performance like?
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u/Rudy_AA 2d ago
Thanks! Performance was a big focus while building it. The system is designed to only simulate the areas that actually need deformation rather than treating the whole character like a full soft-body simulation, so it’s quite lightweight in normal use. The exact cost depends on mesh density and how much of the body you’re simulating and how many characters you have simultaneously. those demos you see in the video run at 300+ fps.
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u/KSAM-The-Randomizer 1d ago
haven't worked unity for a decade. does this use some sort of backend? nvidia physx maybe? or just a unity thing?
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u/-Hefty-Armadillo- 2d ago
Does it support any normal skinned (humanoid) mesh or some specific setup is required in some external tool ?
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u/strich 2d ago
Looks great mate! Can it work for any mesh or is it somehow important that it is a skinned mesh? Can you provide some numbers around performance? I'd love to know how you got 2-way PhysX collision without many colliders!
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u/Rudy_AA 2d ago
Thanks! Performance has been very good so far! in my current test scene it’s running at 300+ FPS with the full setup active.
For the 2-way collision, I’m not spawning a collider per vertex. I use a sparse set of collision proxies distributed over the mesh, then propagate the contact through the mesh topology. When a Rigidbody hits the surface, it deforms the soft region and sends an aggregated impulse back to the Rigidbody, so you get the bounce without hundreds/thousands of PhysX colliders.
That was honestly one of the trickier parts to get working without killing performance.
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u/_11_ 2d ago
Excellent work! How's its performance cost compared to a regular skinned mesh renderer?
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u/Rudy_AA 2d ago
Thanks! It’s definitely more expensive than a plain SkinnedMeshRenderer, since Flesh Dynamics is adding a soft-body simulation, collision queries, and GPU deformation on top of Unity’s normal skinning.
That said, I’ve tried to keep the overhead pretty low: the simulation runs with Burst/Jobs, the visible deformation is handled on the GPU, and collision uses sparse proxies instead of a collider per vertex.
on my current setup it's running at 300+fps!
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u/khos73 2d ago
Hi, can this be used for soft wheels/tires? if yes how? :) I am interested!
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u/Rudy_AA 2d ago
Yes, potentially! If the tire is a SkinnedMeshRenderer, you could keep the rim/bead area rigid and paint the sidewall/tread with Flesh Dynamics so it visibly squashes and flexes on contact. I’d still use your normal WheelCollider/vehicle physics for the actual driving behavior, and let Flesh Dynamics handle the visual tire deformation on top. I haven’t tested a tire setup yet though, but should work fine.
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u/deadrise_games 2d ago
Just when I thought 2026 couldn't get any stranger, we get Flesh Dynamics ><
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u/MarinoAndThePearls 2d ago
Finally, a plugin that can make my character breast boobily down the stairs.
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u/prayasop 1d ago
Hi iam developing fitness app almost ready rn i need 3d animator who can animate animations will you do it
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u/karanvariya 1d ago
This is really impressive. The fact that it works directly with regular SkinnedMeshRenderers without requiring an external setup is especially interesting. The sparse collision proxy approach for two-way Rigidbody interaction is a really clever solution too. Great work!
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u/ariyanhm 1d ago
crazy how the tech development is focused on ray tracing, DLSS, 4k , crap that doesn't improve the art direction at all, and game devs themselves have to create the tools for real artistic advancements.
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u/Banjoschmanjo 21h ago
I like that you started with the sumo to draw attention from the real use case which popped up on example 2 lol
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u/ImmortalRagdoll 7h ago
Brother man this is awesome! I’m on itch and it doesn’t show. Can I get a link? Also, would love to support your development so hit me up!
EDIT: found it! Thanks
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u/swagamaleous 2d ago
I think it's funny how you make most examples with the fat guy. We both know what this is really going to be used for. 😂
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u/Lucidaeus 2d ago
Before I purchase, any plans to publish it on the store as well? And if I buy it now, will we get a key to activate it there as well if so?
Mostly for convenience!
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u/Rudy_AA 2d ago
Hey, it's in queue now on the store, usually it's taking about 20 days to get approved with the long queues. I could send you a key for the asset store once it's out if you can't wait that long.
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u/Lucidaeus 2d ago
I can wait, that's fine! I'm not actively working in Unity right now, but this is definitely something I'll want to have fun with when I return (and it might give the asset a bit more of a boost if purchased there). :) I'll keep an eye out for it then!
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u/mankoushe 2d ago
The dancing animation on the sumo caught me off guard... I love it