ColliderKit — Documentation

v1.1.1 · Blender 4.2 LTS and later · Unity / Unreal 4-5 / Godot 4 · Windows / macOS / Linux

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1. Install

1. Download the add-on ZIP (do not unpack).
2. Edit → Preferences → Add-ons, press the arrow button in the top right corner, choose Install from Disk, pick the ZIP, enable ColliderKit.
3. Press N in the 3D Viewport → ColliderKit tab.

After installing, press N in the 3D Viewport: a tab named ColliderKit appears in the sidebar.

2. Quick start

1. Select the source mesh.
2. Sidebar → ColliderKit → pick engine + shape type.
3. (Optional) toggle Mirror, Group in Collection, Validate Fit.
4. Click Generate Collider.

3. Shape types

Shape	How	Best for
Box	AABB of evaluated mesh	Crates, simple props
Sphere	Bounding sphere	Round props
Capsule	Auto-aligned to longest axis	Characters, columns
Convex Hull	Hull of evaluated mesh, interior stripped	Weapons, rocks
Decimated Mesh	Triangulated + collapse-decimated	Concave props

Box / Sphere / Capsule use the evaluated mesh — Subdivision, Mirror, Shape Keys all contribute.

4. Engine naming

Engine	Naming	Collection
Unreal	UBX_ / USP_ / UCP_ / UCX_	Unreal_Colliders
Unity	the object_col	Unity_Colliders
Godot 4	the object-col	Godot_Colliders

5. Symmetry mirror

Enable Mirror Collider + axis (X / Y / Z). The addon generates the primary collider, then a mirrored copy. Both are then named by the engine convention with an index — for Unreal UCX_Name_01 and UCX_Name_02 (UBX_, USP_, UCP_ for box, sphere and capsule); checked by importing the FBX into Unreal Engine 5.8, which attached both to the mesh. The flip is baked into the mesh — coordinates negated along the axis, normals recalculated to face outward — so the copy keeps a positive scale.

6. Fit validator

Post-generation AABB containment check. Warns if the collider overshoots source bounds by more than 1% of the mesh diagonal. Common causes: too-aggressive Decimate ratio, Sphere on a tall mesh (use Capsule).

7. Compound colliders

Add Compound Shape stacks another collider on the same source (auto-indexed). Remove Last drops the most recent. Merge Compound → Single Hull unions every collider's vertices and computes one convex hull from the union.

8. Convex decomposition

Splits a concave mesh into N convex hulls via recursive bisection.

• Max Hulls — upper bound on pieces (default 4).
• Volume Threshold — drops hulls below this fraction of total volume (default 0.05).

9. Batch generation

Generating colliders one object at a time is where a level goes wrong — the prop you forgot is the prop that falls through the floor. Batch Generate Colliders runs the current shape settings over every mesh in the batch scope at once.

• Batch Scope — the selected meshes, or the whole scene.
• Name Pattern — an optional filter, so a scope of "whole scene" can still mean "only the meshes whose names match".
• Replace Existing — removes an object's previous colliders before making new ones, instead of stacking a second set on top of the first.

Remove Colliders clears every collision shape from the active object, and Remove Last Compound Shape takes back the last shape added to a compound group.

10. Physics materials

A collider carries how the surface behaves, not just its shape. Pick a Material Preset and the friction, bounciness and density sliders fill with the preset's values (table below); pick Custom to set them by hand. Assign Physics Material writes them onto every collider of the active object.

Preset	Friction	Bounce	Density
Concrete	0.8	0.05	2.4
Metal	0.4	0.2	7.8
Wood	0.5	0.3	0.7
Rubber	0.95	0.85	1.1
Glass	0.2	0.1	2.5
Ice	0.05	0.05	0.9
Flesh	0.6	0.1	1.0

11. Collider statistics

The statistics panel lists each collider on the active object with its vertex and face count — a convex hull that came out at 400 vertices is a collider that will cost you at runtime, and the number is the only way to see it before the engine does.

12. Visual style

• Wire display, per-shape color tint (Box green, Sphere red, Capsule blue, Convex yellow, Mesh purple).
• Non-selectable + non-renderable.
• Toggle Collider Visibility hides / re-shows every collider in the scene.
• Show In Front draws them over the geometry they wrap, so a tight shape is still visible.
• Toggle Collider Selection Lock keeps them out of the way of box-select while you keep modelling.
• Refresh Collider Display re-applies these display settings to colliders made earlier or appended from another file.

13. Troubleshooting

"Could not generate collider: empty mesh" — source has no vertices after modifiers.

"Collider overshoots source bounds by X%" — see section 6.

Decimated Mesh is jagged — raise the Decimate ratio closer to 1.0.

14. Limitations

• Built-in decomposer is recursive bisection, not VHACD.
• Physics materials stored as custom props; engine reads them via its own import script.
• Decimated Mesh pre-pass has a 50-iteration / 3-second hard cap.

15. Changelog

v1.1.1 — maintenance release. Minimum Blender is now 4.2 LTS. The package ships the full licence text and an updated README. No changes to the tools.

v1.1.0

• New: Batch Generate Colliders over the selection or the whole scene, with an optional name filter and Replace Existing.
• New: physics materials — seven presets filling friction, bounciness and density, applied to every collider of the object.
• New: collider statistics — vertex and face count per shape.
• New: display controls — visibility toggle, show in front, selection lock, and a refresh that re-applies them to colliders made earlier.
• New: Remove Colliders and Remove Last Compound Shape.

v1.0.0 — initial release.

16. Support & License

Through marketplace messaging. GPL-3.0. Colliders you generate are yours to ship in any commercial project.