Verlet Motion Toolkit 2027

Jiggle bones, hair, tails, ropes and rope bridges for Unity, in 2D and 3D, Burst accelerated, with an optional DOTS layer and no setup beyond a few components.

This asset is included in the Toolkits for Unity Bundle and in Toolkit for Unity Physics.

Bring characters, props and scenery to life. Drop a component on a tail, a cape, a bunch of grass or a strand of hair and it moves with weight, inertia and collision. Hang a rope from a crane, a character or a bridge, tie a rigid body to it and watch it swing, sag and pull back. Everything is tuned with curves and assets in the Inspector, with a documented C# API underneath.

Version 6 is rebuilt on a fixed game-time clock and a stable constraint solver. It looks the same at 30, 60 and 144 FPS, survives frame spikes and focus changes, and collision does not jitter or sink.

✅ Jiggle for any Transform hierarchy: hair, tails, capes, antennae, foliage and bones ✅ Simulated ropes, cables and chains with a generated mesh, pins, collision and cutting ✅ Ropes that hold rigid bodies, with the load pulling back on the body ✅ 2D and 3D, the same simulation behind both ✅ Mass and spring stiffness in real units, varying along the length with curves ✅ Burst compiled solver, with a frame budget so the cost stays bounded ✅ Optional DOTS layer for thousands of chains ✅ Documented API, tested code, example scenes

WHAT'S NEW:
- Frame rate independent (New): The simulation runs on a fixed step of game time. Frame time spikes, throttled windows and slow starts no longer make it flail.
- New solver (New): A stable constraint solver replaces the old one. Settings use real units: node mass in kilograms and spring stiffness in newtons per metre.
- Solid collision (New): Contact is solved inside the simulation for every node and along every bone, so nothing jitters, bounces or sinks into colliders.
- Teleport and pre-warm (New): Move a tree with its root and keep its motion, and settle chains before the first frame so they never start out wagging.
- Ropes that carry weight (New): A rope can hold a rigid body of any mass, several ropes can share a body, and the forces go both ways.
- Rope bridge example (New): A suspension bridge of two ropes and 26 planks with falling cubes, built into the scene so you can inspect how it is made without pressing Play.
- Fast (New): Jiggle trees and ropes run in Burst. The Demo Scene went from about 2 FPS to about 55 FPS in the Editor, and a shared per-frame budget stops it ever eating your frame.
- DOTS layer (New): Chains as entities with systems, bakers for your existing components, a builder for runtime chains, and force and ground authoring.
- One simulation for 2D and 3D (New): The same settings behave the same in both, with the speed limit, stiffness and angle limit working in 2D too.
- Ropes that hang from characters (New): A rope ignores the colliders of the objects it is pinned to, and pinned ends are drawn exactly on them.
- Rebuild at runtime (New): Change a rope's path, spacing or look and rebuild it from code.
- Examples (New): A rope scene with a bridge and a constant speed post, a hair and grass demo, a skinned character, and a 2D scene. All work with the Input System and the legacy Input Manager.
- Documented and tested (New): Every public type and member has documentation, 60 automated tests cover the solver, chains, ropes and DOTS layer, and an AI-agent SKILL guide ships with the package.
- Many fixes: Single pin ropes hang at full length, pausing no longer breaks chains, saved scenes no longer carry runtime data, the 2D angle limit works for hanging chains and more.
- Standalone (Changed): The Verlet Motion Toolkit no longer needs Toolkit for Unity Physics.

Upgrading from 5.x: settings keep their fields but the maths behind them changed, so retune your assets. See the change notes.

WHAT'S INCLUDED:
- Verlet Transforms: Jiggle for hair, tails, capes, antennae and any Transform hierarchy, with a root, an ignore list and several trees per component
- Transform Tree Settings: Mass, damping, elasticity, stiffness, collision radius, angle limit and speed limit as curves along the tree, plus gravity, collision layers, simulation rate and substeps
- 2D Verlet Transforms: The same jiggle in the XY plane with 2D physics collision
- Verlet Line: A simulated rope with a generated mesh, bezier control points, taper, twist, caps and your own profile mesh
- Pins: Hold a rope on an object, make an object follow the rope, or let the rope carry a Rigidbody
- Break and snap: Cut a rope at a point from code or let it snap when overstretched, with events
- Forces: Add wind and impacts to jiggle trees
- Entities: Authoring, bakers, systems and a chain builder for DOTS projects
- Example Scenes: Hair, grass and links, a rope scene with a bridge, a skinned character and a 2D scene
- Knowledge Base: Guides and articles that explain the ideas as well as the API
- Live Discord Support: Direct help from the Heathen team and a community of fellow developers

REQUIREMENTS:
- Unity 6.0 or newer
- The free Heathen Game Framework, which Heathen Toolbox installs for you
- Mathematics and Burst, which Unity installs for you
- Entities, only if you use the DOTS layer