Are Unions Okay to Use for Caves/Openings?

Help and Feedback Building Support
#1

Hi all, I’m thinking about making a map made of primarily Parts.

I’d like to add caves, openings, and other crevices in order to make my map more interesting, but I’m not sure what the best method of doing this actually is.

If I wanted to, for example, make a tunnel through a large part, which option is better?

  1. Use Negate and make it a Union
  2. Build a tunnel out of Parts (At least 4)
  3. Another option I didn’t mention

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image863×394 27.7 KB

I have done research on Unions and have heard they aren’t very performant, but I don’t know if this applies to something as simple as 1 part negating another part.

Any help?

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#2

build a tunnel out of parts, if you make that a union, no one could go through it

#3

In my experience, this isn’t the case if you set CollisionFidelity to PreciseConvexDecomposition.

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#4

I dont really use unions just because they are very annoying and usually cause a lot of errors in coding plus they seem useless to me so i didnt know about that property but still i suggest making it out of parts if you plan on having scripts that include those parts

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#5

Turn every Union to Meshes for optimization

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#6

I assume this would require Blender right?

Also, what makes Unions inherently more unoptimized than a Mesh, even when the Union is relatively simple?

#7

No. You can also do it in Roblox Studio

Double Click > Export Selection

There isn’t much use to have an asset in full quality when you can’t see it, isn’t it?

#8

Are you saying Unions are rendered even when not visible?

If so, then yeah that seems like a massive issue. I’ll consider converting them into meshes.

#9

I’m pretty sure that when you get further away, Unions don’t/can’t become lower quality, unlike Mesh’s

#10

In my experience I only used unions to create holes that players can see through but shouldn’t go through, otherwise it will create some problems with invisible hitboxes

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#11

dont use unions or meshes lol you don’t be able to walk through them and unions cause a lot of lag

just use parts simple

#12

i mean if you don’t care for optimization and would like the ability to change it further down your project for whatever reason then I’d go with number 2. Build a tunnel out of Parts.

But, if you are going for maximum optimization and not worried about specific looks (stud builds with surfaces, etc.) I would agree with this guy on it.

Edit: Just saw this post above me and I somewhat agree with him, but I’m pretty sure you can walk through mesh parts it just doesn’t have 100% accuracy with the collision, and unions are just eh.

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#13

I’ve used Unions in buildings before and have never had issues with Collision when using the right settings. Most of my concerns are strictly based on whether they are performant or not. I don’t plan to use a bunch of these, but I was wondering how much of a difference it’d make it to use Unions over Meshes for simple holes and caves.

#14

you cant use unions for what you’re trying to do in the image you showed me because collisions should be messed up (assuming you use a big part and negate part of it in the middle

#15

Collisions are not messed up if I turn CollisionFidelity to PreciseConvexDecomposition. I’ve really only used this option on simpler unions, so I don’t know how this applies to more complex unions.

Using this option allows players and attack hitboxes (in my game) to pass seamlessly through the gaps.

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#16

ok but still dont use unions when you dont have too lol in that instance you dont need to thats the point

#17

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