Mirror modifier bug - Bisect mode results in "automerge" even if it shouldn't. Need help

Hello guys,

This is a problem that riddles me. The mirror modifier doesn’t do it’s job properly when having “bisect” enabled. There is a threshold to which it will snap vertices to the mirror line. I ruled out all possible things, the mirror pivot is perfectly zeroed out and there is no merge enabled and also no auto merge. It’s also not specific to the latest Blender version, it does the same error in older versions. I’d be thankful if someone wants to look at my scene. Simply put it to “Bisect” and see how the vertex will merge for no reason. bug.blend (843.6 KB)

Hi, nice to see you on BA!

From what I can tell, this is Blender’s poor implementation of units rearing its head. Switching to meters and scaling the object up 100 times “solves” the problem, suggesting that either bisect isn’t aware of actual units or too much is lost in conversion. It might be worth a try reporting this on developer.blender.org, though they may well deem it a “known limitation”. IMHO it’s a straight up bug.

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Hi Stan! Great, thanks for that! Yeah I had the assumption it could have to do with the units which I put to cm. I think it’s a bug too and I’ll go report it :slight_smile:

https://developer.blender.org/T85051 Okay, let’s hope this can be fixed :grinning: :crossed_fingers: