Obi Softbody

About Obi Softbody – Unity Editor Tool & Plugin

Unity Softbody Physics System

Obi Softbody is a particle-based physics engine for simulating deformable materials on the CPU or GPU. Softbodies are represented by ellipsoidal particles connected through shape-matching constraints, allowing objects to deform elastically and plastically while interacting with rigidbodies and other softbodies.

Softbody Simulation

The system uses an oriented-particle XPBD solver and can turn complete objects or specific parts of characters into softbodies. Softbodies can contain thousands of polygons and support collisions, self-collisions, and two-way interaction with rigidbodies.

• One-click softbody generation
• Elastic deformation that restores the rest shape
• Plastic deformation that can be absorbed into the rest shape
• Recovery from plastic deformation
• Two-way rigidbody interaction
• Self-collisions and collisions between softbodies
• Support for non-manifold meshes
• Attachments to colliders or rigidbodies using rotating or fixed orientation links

Solver and Performance Controls

The modular solver allows projects to use only the constraints required by a softbody, with solver iteration counts adjustable per module. Automatic camera culling prevents non-visible softbodies from consuming simulation resources.

The architecture is modular and extensible, while the simulation is described as unconditionally stable, meaning the solver is designed not to blow up during simulation.

CPU and GPU Simulation

CPU simulation depends on the Burst, Jobs, Collections, and Mathematics packages. GPU simulation requires compute shader support, allowing the physics engine to run in either CPU or GPU mode.

Softbody Limitations

Obi Softbody is not a clay or mesh sculpting tool and is not intended as a starting point for creating one. It does not support topological mesh changes such as cutting or tearing.

Use Cases

• Deformable character parts that need physical interaction with colliders or rigidbodies.
• Softbody objects that need both elastic recovery and plastic deformation.
• Projects requiring interactions between multiple deformable objects through self-collision and inter-collision.

Download Obi Softbody from Ultimate Game Assets for your Unity project.

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