Bellisseria - "prim-drift" bug / rotation of prims

[Eibhlin Oconnell]

Hi

I remember, that other users (in chats) mentioned some kind of a "prim-drift" bug / rotation of prims at their Bellisserian homes. I have the same problem. Does anyone know, if there is a way to fix this?

Eibhlin

[Qie Niangao]

I can't imagine a fix to items already affected, short of a region roll-back (which isn't likely).

Unless these were locked objects, I'd really guess a Build Tool mishap.

There is floating point error at extreme altitude but otherwise, "drift": I'm a skeptic (but no expert).

[Eibhlin Oconnell]

Well, I heard of walls that "moved". And in my case it is the roof of an add-on (linkset).

Roof linked to the rest of the building: prim-drift (rotation of 179,500 instead of 180 on the z-axis).

Roof unlinked: no prim-drift

But what if an item is no mod?

[animats]

I wonder if this is related to the bug in llRotBetween. The math there is slightly off for rotations close to 180 degrees. This is documented on the wiki. I've run into this; the error is big enough to put an object at the high-coordinate end of a sim out of position by as much as 0.020m. It's not just roundoff error; that's only about one part in a million, or about 0.0003m. (24-bit floating point, remember. Also, it gets worse for large Z values.)

If something internal is using the same code...