Set CollisionFidelity of a Union obtained using a "SubtractAsync" function

Question

I have a script which randomly generates underground rooms in a BasePart using the SubtractAsync function. It works perfectly fine, however the CollisionFidelity is inaccurate, leading to me being unable to enter the rooms.

Here is the code:

[...]
for _,i in workspace:GetPartsInPart(p) do -- Gets parts to be cut into
    local succ, err = pcall(function() -- pcall ignores part if it cannot be cut into (none of the parts I have with models need to be cut into)
        local fi = i:SubtractAsync({b.RemoveFromTerrain}) -- Cuts
        fi.Parent = i.Parent -- Replaces part with cut part
        i:Destroy()
    end)
end
[...]

Note that despite being quite slow, if I can get it to work, the performance loss I would suffer from using SubtractAsync would be worth it in my case.

I have tried the following:

• Setting the CollisionFidelity in the script after the Union was created -> cannot set because no (The current thread cannot write 'CollisionFidelity' (lacking capability Plugin))
• Setting the CollisionFidelity in Studio on the part I'm cutting into -> BaseParts don't have the CollisionFidelity property

Answer 1

As read in the documentation the second paameter in the SubtractAsync/UnionAsync is the collision fidelity

collisionfidelity: Enum.CollisionFidelity The Enum.CollisionFidelity value for the resulting UnionOperation. Default Value: "Default"

So use

local fi = i:SubtractAsync({b.RemoveFromTerrain}, Enum.CollisionFidelity.PreciseConvexDecomposition) -- Cuts