Reactive Bones

🦴 Secondary Motion Without Making Rigging the Hard Part Reactive Bones is an editor-first secondary motion and collision system for Unity, built for hair, tails, ears, soft motion, straps, cables, tentacles, cloth strips, plants, accessories, and anything else that should react naturally to animation, character movement, forces, and the world around it. Use the bones your model already has, or generate entirely new reactive regions directly inside Unity with the included Reactive Rig Painter. Reactive Bones is designed around a visual, production-friendly workflow. Set up motion, separate animation-driven response from world movement, add procedural sway and flicks, author character collision, interact with ordinary Unity Colliders, tune wind and forces, and optimize the final result without building a custom physics system around it. 🦴 Use Existing Bone Rigs Already have bones for a ponytail, tail, ears, straps, cables, accessories, or another moving part? The Setup Wizard discovers the hierarchy, handles branching chains, supports multiple independent roots, warns about common rig problems, and creates the Reactive Bone setup for you. Virtual endpoints allow even simple or short hierarchies to produce natural tip motion without requiring additional visible bones. 🎨 Generate Reactive Rigs Inside Unity Don’t have the bones you need? The Reactive Rig Painter lets you paint the region of a Mesh Renderer or Skinned Mesh Renderer that should react, then automatically generates the required bones, skin weights, and Reactive Bone chains. Choose the root and tip manually, or let Reactive Bones find them automatically. Control generated bone count, root falloff, centerline smoothing, and weight smoothing. Mirror painted regions across the mesh, assign different Physics Profiles to each layer, and rebuild the rig whenever the recipe changes. Generated rigs are non-destructive. Reactive Bones keeps the original source mesh available, writes generated output separately, and allows the original renderer to be restored. Rig generation also preserves important renderer and skeleton state, including existing bounds context and imported armature transform orientation. ⚙️ Reusable Physics Profiles & Motion Shaping Create reusable Physics Profiles and share them across any number of Reactive Bone chains. Tune the core physical response with settings such as: - Damping - Elasticity - Stiffness - Inertia - Gravity - External force - Collision radius - Solver iterations - Maximum displacement - Update rate - Root-to-tip response curves Reactive Bones also includes dedicated character-motion shaping so every type of movement does not have to affect secondary motion in the same way. Control: - World motion response - Animation/local motion response - Velocity influence - Acceleration shaping - Maximum motion influence - Vertical and jump response limiting - Locomotion pulse - Airborne motion flattening - Motion limiting and smoothing This makes it possible to create cleaner motion for character-mounted rigs while walking, running, jumping, falling, turning, or playing strong animations. Profiles can then be customized to match your own characters, gameplay, and art style. 🌊 Procedural Sway & Flicks Reactive Bones can add life even when the underlying character or object is mostly stationary. Optional procedural motion includes: - Sway for smooth repeating movement - Flicks for irregular, less predictable impulses Use procedural motion for tails, ears, hair, antennae, hanging objects, foliage, accessories, environmental props, and other reactive elements that benefit from subtle autonomous movement. Procedural motion is blended into the same simulation, allowing it to work alongside stiffness, damping, collision, character movement, wind, and other forces. 🛡️ Smart Collision Manager Reactive Bones includes a dedicated Smart Collision Manager for centralized character collision setup. Automatically analyze a charac