Oversized SpecialMesh Collisions

When I use SpecialMeshes, it is mostly because I am trying to make a part larger than 2048 studs. While it LOOKS fine, it has no collisions. I am asking if it is possible to fix that, and make the oversized SpecialMesh be able to collide as it seems it should.

Hi. This detail can be found under the documentation for the SpecialMesh object:

To work around this issue, you can use a MeshPart, which as a property for Collision Fidelity that will attempt to calculate collisions per the geometry of the mesh as you seek.

Mesh Parts can be of nearly any size, although the limitations given for extremely large objects are not something I would be able to warn you of.

I have edited this to remove the section on invisible parts as it does not apply to your issue.

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Okay, before you ask about the 13 million stud size, I am making a spherical Earth in Roblox. I need the sphere to be 13195833 x 13195833 x 13195833 studs in size and a MeshPart can’t do that.

Oofdog, I have attempted to reproduce the sphere of your preference and you happen to be correct.
The size you have specified is simply too large to pack into a single mesh.

A similar post was made in 2020 on the topic of exceeding the 2048 size of individual objects.

The only recommendation I can give you is to generate the simulated size with a store of regions and individual parts replicated to each client depending on their relative whereabouts. Attempting to generate the sphere in it’s entirety this way would likely not perform on current technology.

The presumed number of parts required to make this mesh "collidable":

Formula for surface area of a sphere:
A = (4)(π)(r^2)
r = 13195833 Studs / 2 = 6597916.5 Studs
A = (4)(π)(6597916.5 ^ 2) = 5.47×10^14 or 547,000,000,000,000 Studs^2

The surface area of a part’s topside given the dimensions are 2048 x 2048
2048 * 2048 = 4,194,304 Studs^2

The rough number of topsides to fully compensate for the surface area of this sphere:
547,000,000,000,000 / 4,194,304130,414,963 Parts

In other words, good luck.

Well, I have got the mesh itself working fine, I just need to make the collisions work.

Won’t your characters and models glitch that far from the origin? I don’t see how this will be usable, even if it was possible.

Surprisingly, everything runs quite well. Almost no null zone effect.

Are you close to the origin while testing this? Being that far out would almost certainly introduce floating point precision issues.

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I had this post in mind since last night and want to offer my insight. While a 1.3 million size part isn’t possible, resizing the character is. So my suggestion is that you resize the character instead of trying to bypass a limit that’s intentionally there.

By using this method, I get this result, this black speck is my character at 0.08 scale:

The option I would take in this situation is to create hitboxes that form with the SpecialMesh, which can easily be accomplished just by using Parts.

Wow. What a simple fix. Why didn’t I think of that?

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Wait a minute, how did you get the sphere so smooth?

I used a mesh, it caused studio to hang for a few minutes though:

sphere.obj (324.3 KB)