really confused about convex mesh collider triangle limit

Physics
1

I had thought that you couldn’t set a mesh collider to be convex for meshes with over 255 triangles.

But in Unity 5.6, I’m able to set mesh colliders to convex for models with a much higher triangle count.

For example, I have a table made up of 6 rounded cubes, and the total triangle count is 25920.
But in the editor, I’m able to set the mesh collider to be convex.

See?

1157×356 353 KB

The documentation says this:
"Convex Mesh Colliders are limited to 255 triangle"

So what I believe is happening is that it doesn’t matter how many triangles the mesh has, it only matters how many triangles the generated collider has. In the above example, the high-polygon table is wrapped in what looks like a fairly low triangle convex collider. Is this correct? If so, I have a question:

How can we tell (from code) whether or not a collider can be successfully set to be convex? It seems that we can’t rely upon the mesh triangle count to determine this. What I’m trying to do is set the colliders to convex if this will work, and if not, Destroy the mesh collider and add a BoxCollider instead.

2

Would love to find an answer to this. I see that in most cases, when setting to convex normally doesn’t work, it will work if I set meshCollider.InflateMesh=true. But this is slow so I only want to do this when necessary, and I can’t figure out (from code) when it is necessary. I tried surrounding my “mesh.convex = true” with a try/catch, but the errors aren’t getting caught.