The following is a Roblox Studio bug that I noticed today, having to do with position values in the properties menu. It reproducible 100% of the time and has occurred for others. It may seem like an unimportant visual error, but it can introduce problems. Place file is attached below.
Description of what is supposed to happen
When selecting two or more parts, the shared values will be visible in the properties menu. Values that are not the same will be blank in the properties window.
For example, parts that share the same XYZ position will have their shared position values visible in the properties menu when selecting them both.
Parts that don’t share one or any of the values will have those respective values appearing as blank in the properties menu when both parts are selected.
Here is a visual representation of what I mean:
Two parts are selected. They share the same Y and Z value, so it is visible in the properties menu. The two parts have a different X value, so the value is blank.
This is normal behavior.
Bug Description
Following a certain method to reproduce the error will cause parts that share the same position values to be treated in the properties menu as if they do not share the same position values. This is an issue, for example, when using plugins that check for parts sharing the same values to find duplicate parts. Even though the parts do share the same position, it won’t be detected. This bug is easily reproducible and happens 100% of the time.
OKevinO’s duplicate finder and Tomarty’s Geom Tool duplicate finder both fail to find the duplicate when this bug is introduced.
Example
In what use-case does this become a problem?
In the following example, a building technique will fail to work due to the bug:
There are two identical models. Each model has a different set of missing parts that were deleted, now having four parts total each.
Model #1 has partA, partB, partD, and partF
Model #2 has partA, partB, partC, and partE
We can repair the original model by combining both Model#1 and Model#2, by moving them into the same XYZ position and then deleting duplicates with a plugin.
PartA and PartB become duplicates as both models have them. Using a duplicate remover will leave us with a single model that only has one of each part: PartA, PartB, PartC, PartD, PartE, and PartF, thus the models that were split into two.
The bug prevents the duplicates from being deleted, and deleting duplicates manually is not an option if you have a model with hundreds of parts that need to be filled.
Steps to produce bug
1 - Create two parts. One part will be used as a centerpoint. The green cylinder is our centerpoint, while the white block is what we will be producing the bug with.
2 - Mirror the white block using the green cylinder as a centerpoint. The red one is our mirrored part. Mirroring is an essential part of the bug, and will not occur if you simply duplicate and move the white part manually.
3 - Use the green cylinder as a pivot point to rotate the mirrored (red) part 90 degrees. The red part will now be in the same XYZ position as the white part. Use any number of available building tools to set the pivot point correctly.
4 - If done correctly, the bug has now been produced. If you look at each part individually, their XYZ values will be exactly the same. If you select both parts and look again, some or all of the values will be blank as if they are different. Plugins now won’t detect the duplicate.
bug.rbxl (19.3 KB)