For a really long time since csg became a feature on ROBLOX I have always had a hard time trying to get a specific selection or bounding box shape out of a union. I know that the selection box is based on the rotation and angle of one part, but it is never consistent between unions that it’s just so frustrating to get the desired box.
To give a little insight and to provide an example? this is a model of a vtol propeller that I made, it is five unions making up the blades and one union making up the center.
In order to make this propeller rotate efficiently I want to make it a single part, which can be achieved by unioning them all together. I want the selection box to be flat and a a 0,0,0 rotation.
So upon unioning them, I get this wacky selection box that just looks annoying and makes my job harder.
When I remove the union and try again, it will appear different at random centering around a single part.
Sometimes I thought that this is based on what part I select first or select last, which still isn’t consistant. Lately I find that my camera angle sometimes changes the selection boxes orientation but it still isn’t consistant.
Does anybody know if there is any actual way to make the selection box be what you want it to be?
The resulting union’s bounding box will use the orientation of the first part in the selection. In this case, it’s trying to align everything to the first blade you selected. You can get a better result by selecting one of the more flat pieces (e.g. propeller center cylinder) first, or if there aren’t any flat pieces available, create a flat NegateOperation that isn’t touching anything but has the intended orientation.
Plugins shouldn’t affect the bounding box calculation. But if it does then use Studio’s vanilla CSG tool and do what Echo said above for the one negate.
