Cover of Universal Colliders with Deprecated Stamp

As some of you may have already noticed, on February 26, 2022, Universal Colliders got missing from the Asset Store. What did it happen? Everything is explained here, but don’t worry: Universal Colliders will come back!

What happened to the package?

Yesterday (as of February 27), I deprecated the package on the Asset Store. It means that no new user can get it, yet users that already bought it can still download it.

Deprecation notice on the Unity Asset Store

Why was it deprecated?

That’s the point. For a bit of history, Universal Colliders is quite a young package (two months old), so it was released it what can be considered a beta version. I was not complete, yet worked sufficiently well to consider it worth releasing. However, a few upgrade were needed in a near future.

Here is the point: due to technical difficulties (e. g.: time), I am not able to bring the updates by the expected time. Before I was crowded with unsatisfied users, I chose to remove it from now, and it will come back in a new release!

Universal Colliders: New Releases Incoming

As the beta phase is over, it was the occasion of experimenting with a quite a few parameters:

  • Price: $30 was chosen to align the package on its competitors, and generate initial income. Now that it’s done, it can be the occasion to lower it.
  • Trailer: expect a new one with technical insights!
  • Features: new core feature should come soon!
  • Internationalization: Chinese translation incoming

You may wonder what new feature will come in the new releases, and when. I won’t say much here, but we are aiming to make the package truly universal, so stay tuned!

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Universal Colliders Project Logo

Tired of setting up Unity colliders? We propose a new asset suitable for everything from static spheres to non-convex rigid bodies! The Universal Colliders projects comes to deployment, and a whole new world opens! One Asset to Unite them All, isn’t it?

Please Note: As of today, the Asset is being evaluated before publishing in the Unity Asset store.

The trailer of the asset

How It Works

Everything starts by a box. Literally. The idea is to generate consecutive oriented bounding boxes: at each step, generate a bounding box for the vertices, then subdivide it in two. The interesting part is that you are not only limited to boxes, as you can switch to spheres, capsules, and even meshes!

Several level of recursion (left) and the colliders associated (green). A chain was generated with this system on the right.

Once your generation is complete, you have nothing more to do, just launch the scene and the colliders will appear! In some cases you may want to apply manual modification. It is entirely possible, since each collider is a new GameObject that can be modified scaled following your needs. You can also subdivide these object, to get better details in specific areas.

Please find the online documentation here:

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Unity Showing Non-convex error

As of today (2021), Unity struggles with colliders, making a nightmare for game designers. It should not be. This page introduces the problem and give you solutions.

The Problem

You roughly have the choice between a box, a sphere or a capsule for efficient computation. If you really want precision, Unity offers the mesh collider option, much slower, limited to 256 triangles, and … for convex colliders only.

Why is tit so limited? The answer is: effectiveness and simplicity. In video games, collision between convex shapes are privileged because there are simple to compute. Here is a brief list of most common colliders:

  1. Sphere
  2. Axis-Aligned Bounding Box (AABB)
  3. Oriented Bounding Box (OBB)
  4. Discrete Oriented Polytope of n-summits (n-DOP)
  5. Convex hull (convex mesh in Unity)
  6. Non-convex hull

See the Wikipedia page over bounding volumes.

The more complex it is, the more precision you get, but collision detection become costly. You should scarcely use convex mesh colliders in Unity because it generates lots of tests, and non-convex shape even more scarcely, this is why they can’t be used with rigidbodies.


Keep it simple, stupid

KISS principle

It may seem a constraint, may those simple shapes are a good way to make the games running smoothly. In fact, you should avoid using mesh colliders at a maximum. Keep in mind that 16 boxes are always more efficient than a convex mesh collider of 256 triangles. In fact, you should only use spheres, capsules and boxes.

However, setting up 16 boxes by hand is a nightmare. This is why we created the Universal Collider Asset, which makes good use of Unity types to generate sets of colliders. We use a method called OBBTree, which make things as smooth as possible.

Why is this solution better? The Asset Store provides other packages using AABBTree, K-DOP, and near-convex hulls. I will cover each of the subject:

  • AABBTree: similar to OBBTree, but the tree is made of cubes all aligned in the objects’ space. No rotation. It means that for the same precision, you will have a much higher recursion level, hence more cubes, and you will use more resources for physics.
  • K-DOP: in term of complexity, K-DOP is efficient but only generates convex hulls. I did not find a pure K-DOPTree packet on the Asset Store, as it seems it is not cost worthy.
  • Near-convex hull: this method is based on dividing a non-convex mesh into near-convex parts. The more division you do, the more precision. However, it quickly uses computation time as you are generating mode and more convex shapes.

Capsules and other primitives

What about capsule colliders? It is a common shape in video games, memory efficient, so Unity added it. One could think of other primitives (tetrahedrons, cones, dodecahedron, etc…) but Unity decided there was enough types.


As it appears, Unity did not really change its collision components through years. However, the game engine could really get buffed with an improved colliders generation system, as colliders and triggers are used in (almost) every games.

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