[Roblox] Fast AABB

local inf = math.huge
local axes = {'X','Y','Z'}

local function fastComputeAABB(model)
    local min = { inf, inf, inf }
    local max = { -inf, -inf, -inf }

    for _,obj in pairs(model:GetDescendants()) do
        if obj:IsA("BasePart") then
            local cf = obj.CFrame
            local origin = cf.p
            local up,right,look = cf.upVector,cf.rightVector,cf.lookVector

            local halfSize = obj.Size/2
            local hx,hy,hz = halfSize.X, halfSize.Y, halfSize.Z
            local worldR,worldU,worldL,vertex

            for x = -1,1,2 do
                worldR = right * (x * hx)
                for y = -1,1,2 do
                    worldU = up * (y * hy)
                    for z = -1,1,2 do
                        worldL = look * (z * hz)
                        vertex = (origin + worldR + worldU + worldL)
                        for axisId = 1,3 do
                            local coord = vertex[axes[axisId]]
                            if coord < min[axisId] then
                                min[axisId] = coord
                            end
                            if coord > max[axisId] then
                                max[axisId] = coord
                            end
                        end
                    end
                end
            end
        end
    end

    min = Vector3.new(unpack(min))
    max = Vector3.new(unpack(max))

    return Region3.new(min,max)
end