ColliderKit — Game-Ready Collision Mesh Authoring for Blender

Five shape types, engine-correct naming, symmetry mirror, compound colliders and a fit validator — all in one sidebar tab.

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Why ColliderKit

Generating clean collision geometry by hand is repetitive and error-prone. Unity wants a col suffix, Unreal wants UCX / UBX / USP / UCP prefixes, Godot wants a col mesh. Forget one rule and your physics import breaks.

ColliderKit fills the gap with one sidebar: pick a shape, pick the engine, click Generate. Box, Sphere, Capsule, Convex Hull, or Decimated Mesh — all named correctly, parented to the source, grouped in an engine-named collection, and validated against the source bounds before you ship.

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Features

Five shape types

• Box — modifier-aware bounding box (Subdivision, Mirror, Shape Keys all contribute)
• Sphere — bounding sphere with configurable segments
• Capsule — auto-aligned to the longest axis
• Convex Hull — from the evaluated mesh, interior geometry stripped
• Decimated Mesh — triangulated and collapse-decimated to a target ratio

Engine-correct naming

• Unreal — UBX (box), USP (sphere), UCP (capsule), UCX (convex / mesh) prefixes
• Unity — a col child mesh
• Godot — a col child mesh

Engine-named auto-collection

Generated colliders are linked into an engine-named collection (Unity, Unreal or Godot Colliders) so the outliner stays clean.

Symmetry mirror

Generate one collider, and the addon writes the mirrored copy across the X, Y or Z axis with corrected normals.

Fit validator

A post-generation check verifies the collider stays inside the source mesh bounds. Configurable tolerance, with a warning if it overshoots.

Compound colliders

Stack multiple shapes on one source — auto-indexed (01, 02, and so on). Merge them back into a single convex hull with one click when you decide compound is overkill.

Convex decomposition

Split a concave mesh into several convex hulls. A volume-threshold filter drops noise hulls below a configurable fraction of the total volume.

Visual distinction

• Wireframe display plus a per-shape colour tint
• Locked from selection in the viewport (no accidental grabbing)
• Overlay toggle for show / hide

Safe on degenerate input

Empty meshes, zero-radius bounds, and under-four-vertex hulls are skipped with a clear warning instead of producing invalid colliders. The internal decimation pre-pass has a hard iteration and time cap so the UI never stalls.

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Compatibility

• Blender: 4.2 LTS and later (tested on 4.2 LTS and 5.2)
• OS: Windows / macOS / Linux — pure Blender Python, no DLL
• Unity: any version that uses the col child-mesh convention
• Unreal Engine 4 / 5: the FBX importer auto-detects the UCX / UBX / USP / UCP prefixes
• Godot 4: auto-creates collision on a col mesh

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What you get

• ColliderKit add-on (Python only, no DLL)
• README with full quick-start guide
• Free updates for v1.x
• Support through marketplace messaging

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Install

Preferences, Add-ons, Install, pick the downloaded ZIP, enable. The ColliderKit sidebar tab appears in the 3D Viewport (press N).

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License

GPL-3.0. Standard for Blender add-ons. The license applies to the add-on code only — the colliders you generate are yours to ship in any commercial project.