# How to get a convex hull Unity can use for a high-poly object?

I’ve got some oddly-shaped asteroids, very curvy and smooth. When I was using them as small objects, a capsule collider was a good enough approximation of their shapes, but now I’m using them scaled-up so the differences between their actual shapes and the capsule collider are stark.

Because touching one of the colliders will instantly kill the player and restart the level, I need a much better fit. I tried having Unity build a convex mesh collider, but it refused saying that the collider would be too complex (more than 255 triangles). So I bought a math library to generate a convex hull, and Unity refused to use it because that hull was more than 255 triangles (so that was money wasted).

Before I spend more time and cash, what’s the best approach for solving this problem? Do I need a specialized tool to generate a convex hull with less than 255 triangles? Do I need a tool to simplify my asteroid so that Unity can then generate a usable convex hull? Do I need to learn how to manually build my own meshes for the colliders? Should I just throw away these asteroids and get some simplier ones? I’ve also heard there’s a way to put multiple colliders on one object which work together to approximate its shape - if that’s the best route, will someone please link me some docs or a tutorial?

Apologies for my flailings - I’m new to Unity and often find that I can’t get the information I need because I haven’t learned enough terminology to form good internet search queries. Thanks so much!

I solved this by learning how to use Blender at a basic level. I loaded my source meshes into blender, used the built-in mesh ‘decimator’ modifier, and exported the simplified result as a new mesh which I could then use as a collider. I did this once for each of the 11 source meshes I had which were too complicated for Unity to use.