WeldConstraint works very badly and shifts part when using

Bug Reports Engine Bugs
#1

I created the building from separate parts, after I finished making all the objects in the building, I removed the anchor, then highlighted all the parts and just clicked on the Weld tool and everything automatically welded, but after that a lot of parts shifted and now my house looks unpleasant because of these spotty linear flickers. I have 2 options - either put up with the model being like this, or spend a couple of hours re-creating the walls, but who’s guaranteeing it won’t want to move again?

And if only with this house, but so with all my other buildings

Weld, a very bad effect on the model, here’s a bug that I detected

  1. in Weld needs to fix the error with the shift, otherwise it is not possible to use this tool, because it spoils the model

  2. Does anyone know how to use Weld so that it does not shift part?

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#2

Your videos were very confusing so I couldn’t see in detail how you built the complete object tree.

But initially there is no point in using WeldConstraint unless you intend to move this object within the game. If the house is not moved at any time, you can just group the parts and leave them anchored.

If you want to move the objects during the game then yes, use WeldConstraint. But in this case, there’s a trick: all child objects (Part1) must be Anchored = false, only the parent must be Anchored = true.

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#3

In my game, the floor of the house is attached to the site (anchor), but when it happens, for example, event X, weld is removed, and the object disintegrates.

I created a house from the parts and everything was fine, after creating a house, I highlighted all the parts and just clicked on weld. I started to test the game (run), looked whether the house is not falling apart, and everything is fine, and I notice something is wrong, I stop the game, and I understand that weld displaced the parts.

In the video I showed how I applied weld
edit: the video doesn’t seem to play, so here’s a link to the video
video

And everything seemed okay, but then I decided to cancel and do the same thing, and at some point there was a shift parts
edit: the video doesn’t seem to play, so here’s a link to the video
video

I can’t figure out what exactly causes the shift, but I had a shift on all objects (in the video above showed)

I also tried to not weld the whole house, and weld the walls to the floor, and then the wall welded to the union. and so I welded, and canceled the action 10 times, but the shift did not happen.

From which I conclude that if parts are welded a lot, there will be a shift, but if not much is welded, the shift is unlikely to happen.

I do not know how it works, I’m just saying what I get, weld is very strange and crooked

updated: Basically, because the parts don’t want to weld to the union I have to lower the parts so that it goes into the union. by doing so, happen welding and then I bring the parts back.
Because of the movement, in fact, I don’t know how, but micro shifts happen.

updated2: I remembered that when I made the car, welding parts in it, there was also a shift in parts, although I did not move the car after welding in the studio itself in any way.
In short, WeldConstraint is a very strange thing, and it is not known what determines whether there will be a shift or not.

But the fact is that it is, and it is clearly a bug and should be corrected

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#4

Well, I see you didn’t read what I wrote.
If you do not intend to move the house or any objects while playing the game, just DO NOT use WeldConstraint.

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#5

This is already ridiculous.
After all, it turns out that you have not read what I wrote, or misunderstood me.
Again, in my game, event X occurs (Let there be a hurricane), and the house must break apart and fly around the hurricane.
Example 2: I have a lighthouse, and when event X occurs(Let there be an earthquake) the foundation should unhook from the surface(surface with anchor) and the lighthouse should fall, and as soon as some part of the lighthouse touches the ground, it gradually collapses further

I’M IMITATING AS IF THERE WERE AN EARTHQUAKE:

In any case, I realized that this problem can not be solved. Need to inform the employees who deal with bugs with construction.
Again, I originally wanted to write in the Bug Report. But I can not create there topics (requires Trust Level: Regular, and I have a member)

undated: Even if I didn’t have to weld parts in buildings, can’t make a car without welding. (Since the machine must move, the anchor cannot be used, so a weld is used.)
To quote from my last words:

I remembered that when I made the car, welding parts in it, there was also a shift in parts, although I did not move the car after welding in the studio itself in any way.
In short, WeldConstraint is a very strange thing, and it is not known what determines whether there will be a shift or not.

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#6

Your method of welding isn’t going to work the way you proposed, not for a house nor for a car. When you weld constraint one part to another, there should be a central part (like a root part) that all the other parts are weld constrained to. And you must go in and specify that part as attachment 1 and the root part as attachment 2. If you do not go step by step and do this, and instead just regular weld all parts together, then when you move it, even the slightest move out of place will render these welds to “disappear” since the contact that they had is no longer touching. A weld constraint will keep the parts “connected” even when they don’t physically touch. A regular weld won’t do this, they must touch.

If you are using a model from the gallery, most were built when roblox was using welds and not weld constraints, this is the main reason you are experiencing this issue and why weld constraints are more commonly used now.

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#7

It seems that you not only did not read or look at anything, but even the title did not read, because it said that I use Weld Constraint

IN ALL VIDEOS USE Weld Constraint. Before creating anything, I learned that Weld is obsolete

https://developer.roblox.com/en-us/api-reference/class/Weld

there are no such models in ToolBox(that I create), no one does so at home

That is, if someone wants to make a wall, he will make a wall of 1 part, it makes no sense to make a wall of 9 parts, it makes no sense and inconvenient. In my models everywhere walls consist of several parts, because I need it for the game (cannot be created a part with Surface)

It feels like you have the wrong topic, or do not understand that the old weld is not displayed in roblox studio.

More precisely, the old weld is visible as a white rectangle, and Weld Constraint is a green/gray lines that you can turn on or off and they are visible in all my videos

1 Like
#8

Hey @Petrovu4R

Thanks for the report! This is a known issue, however, our engineers want to investigate your problem as well. Therefore, could you please add the repro file with the place from the videos to your initial post? In case it has private content, you can send it via DM to me, or send it to Log Files with the same title, where only Roblox Staff can see it.

Thanks!

3 Likes
#9

Any update on this issue? It makes building anything a living nightmare. It would be nice if it was fixed sometime soon

#10

Hello all! Thanks for the report. This is an inherent floating point precision issue, and will probably never go away, unfortunately. It’s a fundamental computational problem.

That being said, we recently made a change that should improve a lot of use cases, notably to prevent subtle position drifts when Enabling → Disabling over and over again by adding certain fuzzy tolerances for whether or not to update part positions. We never got a placefile for your specific case, so I can’t confirm whether or not it will fix this specific model, but I hope this change at least helps in a majority of future scenarios.

#11

@katablx Hello, If it is a computer-related issue, do you think only he will have this problem or will everyone see the issue from their game?